Lp-mixed affine surface area

NASA Astrophysics Data System (ADS)

Wang, Weidong; Leng, Gangsong

2007-11-01

According to the three notions of mixed affine surface area, Lp-affine surface area and Lp-mixed affine surface area proposed by Lutwak, in this article, we give the concept of ith Lp-mixed affine surface area such that the first and second notions of Lutwak are its special cases. Further, some Lutwak's results are extended associated with this concept. Besides, applying this concept, we establish an inequality for the volumes and dual quermassintegrals of a class of star bodies.

Investigation of the electrochemically active surface area and lithium diffusion in graphite anodes by a novel OsO4 staining method

NASA Astrophysics Data System (ADS)

Pfaffmann, Lukas; Birkenmaier, Claudia; Müller, Marcus; Bauer, Werner; Mitsch, Tim; Feinauer, Julian; Krämer, Yvonne; Scheiba, Frieder; Hintennach, Andreas; Schleid, Thomas; Schmidt, Volker; Ehrenberg, Helmut

2016-03-01

Negative electrodes of lithium-ion batteries generally consist of graphite-based active materials. In order to realize batteries with a high current density and therefore accelerated charging processes, the intercalation of lithium and the diffusion processes of these carbonaceous materials must be understood. In this paper, we visualized the electrochemical active surface area for three different anode materials using a novel OsO4 staining method in combination with scanning electron microscopy techniques. The diffusion behavior of these three anode materials is investigated by potentiostatic intermittent titration technique measurements. From those we determine the diffusion coefficient with and without consideration of the electrochemical active surface area.

Editors' Choice—Electrochemically Active Surface Area Measurement of Aged Pt Alloy Catalysts in PEM Fuel Cells by CO Stripping

DOE PAGES

Garrick, Taylor R.; Moylan, Thomas E.; Carpenter, Michael K.; ...

2016-12-13

The use of hydrogen adsorption/desorption (HAD) is a convenient method to measure the Pt surface area of a catalyst. However, it was shown that electrochemical charges measured by this technique can underestimate the Pt surface area by up to a factor of two for small Pt nanoparticles or Pt alloy nanoparticles. Electrooxidation of CO, so-called CO stripping, has been shown to be more accurate. Yet measurements of CO stripping in MEAs are scarce, especially on high activity alloy catalysts. In this study we investigated CO stripping and the ratio between Pt surface areas measured by CO and by HAD onmore » several Pt and Pt alloy catalysts. The effects on these measurements of temperature and catalyst aging by voltage cycling are discussed.« less

Editors' Choice—Electrochemically Active Surface Area Measurement of Aged Pt Alloy Catalysts in PEM Fuel Cells by CO Stripping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garrick, Taylor R.; Moylan, Thomas E.; Carpenter, Michael K.

The use of hydrogen adsorption/desorption (HAD) is a convenient method to measure the Pt surface area of a catalyst. However, it was shown that electrochemical charges measured by this technique can underestimate the Pt surface area by up to a factor of two for small Pt nanoparticles or Pt alloy nanoparticles. Electrooxidation of CO, so-called CO stripping, has been shown to be more accurate. Yet measurements of CO stripping in MEAs are scarce, especially on high activity alloy catalysts. In this study we investigated CO stripping and the ratio between Pt surface areas measured by CO and by HAD onmore » several Pt and Pt alloy catalysts. The effects on these measurements of temperature and catalyst aging by voltage cycling are discussed.« less

Relationships among particle number, surface area, and respirable mass concentrations in automotive engine manufacturing.

PubMed

Heitbrink, William A; Evans, Douglas E; Ku, Bon Ki; Maynard, Andrew D; Slavin, Thomas J; Peters, Thomas M

2009-01-01

This study investigated the relationships between particle number, surface area, and respirable mass concentration measured simultaneously in a foundry and an automotive engine machining and assembly center. Aerosol concentrations were measured throughout each plant with a condensation particle counter for number concentration, a diffusion charger for active surface area concentration, and an optical particle counter for respirable mass concentration. At selected locations, particle size distributions were characterized with the optical particle counter and an electrical low pressure impactor. Statistical analyses showed that active surface area concentration was correlated with ultrafine particle number concentration and weakly correlated with respirable mass concentration. Correlation between number and active surface area concentration was stronger during winter (R2 = 0.6 for both plants) than in the summer (R2 = 0.38 and 0.36 for the foundry and engine plant respectively). The stronger correlation in winter was attributed to use of direct-fire gas fired heaters that produced substantial numbers of ultrafine particles with a modal diameter between 0.007 and 0.023 mu m. These correlations support findings obtained through theoretical analysis. Such analysis predicts that active surface area increasingly underestimates geometric surface area with increasing particle size, particularly for particles larger than 100 nm. Thus, a stronger correlation between particle number concentration and active surface area concentration is expected in the presence of high concentrations of ultrafine particles. In general, active surface area concentration may be a concentration metric that is distinct from particle number concentration and respirable mass concentration. For future health effects or toxicological studies involving nano-materials or ultrafine aerosols, this finding needs to be considered, as exposure metrics may influence data interpretation.

High-surface-area, dual-function oxygen electrocatalysts for space power applications

NASA Technical Reports Server (NTRS)

Ham, David O.; Moniz, Gary; Taylor, E. Jennings

1987-01-01

The processes of hydration/dehydration and carbonation/decarbonation are investigated as an approach to provide higher surface area mixed metal oxides that are more active electrochemically. These materials are candidates for use as electrocatalysts and electrocatalyst supports for alkaline electrolyzers and fuel cells. For the case of the perovskite, LaCoO3 , higher surface areas were achieved with no change in structure and a more active oxygen electrocatalyst.

Homogeneous near surface activity distribution by double energy activation for TLA

NASA Astrophysics Data System (ADS)

Takács, S.; Ditrói, F.; Tárkányi, F.

2007-10-01

Thin layer activation (TLA) is a versatile tool for activating thin surface layers in order to study real-time the surface loss by wear, corrosion or erosion processes of the activated parts, without disassembling or stopping running mechanical structures or equipment. The research problem is the determination of the irradiation parameters to produce point-like or large area optimal activity-depth distribution in the sample. Different activity-depth profiles can be produced depending on the type of the investigated material and the nuclear reaction used. To produce activity that is independent of the depth up to a certain depth is desirable when the material removed from the surface by wear, corrosion or erosion can be collected completely. By applying dual energy irradiation the thickness of this quasi-constant activity layer can be increased or the deviation of the activity distribution from a constant value can be minimized. In the main, parts made of metals and alloys are suitable for direct activation, but by using secondary particle implantation the wear of other materials can also be studied in a surface range a few micrometers thick. In most practical cases activation of a point-like spot (several mm2) is enough to monitor the wear, corrosion or erosion, but for special problems relatively large surfaces areas of complicated spatial geometry need to be activated uniformly. Two ways are available for fulfilling this task, (1) production of large area beam spot or scanning the beam over the surface in question from the accelerator side, or (2) a programmed 3D movement of the sample from the target side. Taking into account the large variability of tasks occurring in practice, the latter method was chosen as the routine solution in our cyclotron laboratory.

Effect of organic fuels on surface area and photocatalytic activity of scheelite CaWO4 nanoparticles

NASA Astrophysics Data System (ADS)

Manjunath, Kusuma; Gujjarahalli Thimmanna, Chandrappa

2018-03-01

Discrete nanoscale calcium tungstate (CaWO4) nanoparticles with exquisite photocatalytic activities were synthesized through ultra-rapid solution combustion route. Here, we aim to study the effect of different fuels on the synthesis of CaWO4 nanoparticles which lead to improve the characteristic properties and morphological evolution of the powders. From BET surface area measurement, it is observed that CaWO4 nanoparticles synthesized by using citric acid as fuel exhibits relatively large surface area (31.78 m2 g‑1) as compared to other fuels. The powder x-ray diffraction (PXRD) studies reveal that CaWO4 nanoparticles belong to scheelite type tetragonal system. The morphology of CaWO4 nanoparticles investigated using scanning electron microscopy (SEM) reveals that the powders are highly porous and agglomerated. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of the CaWO4 nanoparticles show that a well-dispersed nearly oval-shaped nanoparticles with variable dimensions and lattice spacing that depends on the type of fuels used in the synthesis. The selected area electron diffraction (SAED) patterns of CaWO4 nanoparticles exhibit several concentric rings with bright spots indicating the polycrystalline nature of the powders. Investigation on photocatalytic activity of CaWO4 nanoparticles synthesized using citric acid shows highest (∼93%) degradation of methylene blue (MB).

Non-activated high surface area expanded graphite oxide for supercapacitors

NASA Astrophysics Data System (ADS)

Vermisoglou, E. C.; Giannakopoulou, T.; Romanos, G. E.; Boukos, N.; Giannouri, M.; Lei, C.; Lekakou, C.; Trapalis, C.

2015-12-01

Microwave irradiation of graphite oxide constitutes a facile route toward production of reduced graphene oxide, since during this treatment both exfoliation and reduction of graphite oxide occurs. In this work, the effect of pristine graphite (type, size of flakes), pretreatment and oxidation cycles on the finally produced expanded material was examined. All the types of graphite that were tested afforded materials with high BET surface areas ranging from 940 m2/g to 2490 m2/g, without intervening an activation stage at elevated temperature. SEM and TEM images displayed exfoliated structures, where the flakes were significantly detached and curved. The quality of the reduced graphene oxide sheets was evidenced both by X-ray photoelectron spectroscopy and Raman spectroscopy. The electrode material capacitance was determined via electrochemical impedance spectroscopy and cyclic voltammetry. The materials with PEDOT binder had better performance (∼97 F/g) at low operation rates while those with PVDF binder performed better (∼20 F/g) at higher rates, opening up perspectives for their application in supercapacitors.

Proton exchange membrane fuel cell model for aging predictions: Simulated equivalent active surface area loss and comparisons with durability tests

NASA Astrophysics Data System (ADS)

Robin, C.; Gérard, M.; Quinaud, M.; d'Arbigny, J.; Bultel, Y.

2016-09-01

The prediction of Proton Exchange Membrane Fuel Cell (PEMFC) lifetime is one of the major challenges to optimize both material properties and dynamic control of the fuel cell system. In this study, by a multiscale modeling approach, a mechanistic catalyst dissolution model is coupled to a dynamic PEMFC cell model to predict the performance loss of the PEMFC. Results are compared to two 2000-h experimental aging tests. More precisely, an original approach is introduced to estimate the loss of an equivalent active surface area during an aging test. Indeed, when the computed Electrochemical Catalyst Surface Area profile is fitted on the experimental measures from Cyclic Voltammetry, the computed performance loss of the PEMFC is underestimated. To be able to predict the performance loss measured by polarization curves during the aging test, an equivalent active surface area is obtained by a model inversion. This methodology enables to successfully find back the experimental cell voltage decay during time. The model parameters are fitted from the polarization curves so that they include the global degradation. Moreover, the model captures the aging heterogeneities along the surface of the cell observed experimentally. Finally, a second 2000-h durability test in dynamic operating conditions validates the approach.

Active Free Surface Density Maps

NASA Astrophysics Data System (ADS)

Çelen, S.

2016-10-01

Percolation problems were occupied to many physical problems after their establishment in 1957 by Broadbent and Hammersley. They can be used to solve complex systems such as bone remodeling. Volume fraction method was adopted to set some algorithms in the literature. However, different rate of osteoporosis could be observed for different microstructures which have the same mass density, mechanical stimuli, hormonal stimuli and nutrition. Thus it was emphasized that the bone might have identical porosity with different specific surfaces. Active free surface density of bone refers the used total area for its effective free surface. The purpose of this manuscript is to consolidate a mathematical approach which can be called as “active free surface density maps” for different surface patterns and derive their formulations. Active free surface density ratios were calculated for different Archimedean lattice models according to Helmholtz free energy and they were compared with their site and bond percolation thresholds from the background studies to derive their potential probability for bone remodeling.

Constrained Adherable Area of Nanotopographic Surfaces Promotes Cell Migration through the Regulation of Focal Adhesion via Focal Adhesion Kinase/Rac1 Activation.

PubMed

Lim, Jiwon; Choi, Andrew; Kim, Hyung Woo; Yoon, Hyungjun; Park, Sang Min; Tsai, Chia-Hung Dylan; Kaneko, Makoto; Kim, Dong Sung

2018-05-02

Cell migration is crucial in physiological and pathological processes such as embryonic development and wound healing; such migration is strongly guided by the surrounding nanostructured extracellular matrix. Previous studies have extensively studied the cell migration on anisotropic nanotopographic surfaces; however, only a few studies have reported cell migration on isotropic nanotopographic surfaces. We herein, for the first time, propose a novel concept of adherable area on cell migration using isotropic nanopore surfaces with sufficient nanopore depth by adopting a high aspect ratio. As the pore size of the nanopore surface was controlled to 200, 300, and 400 nm in a fixed center-to-center distance of 480 nm, it produced 86, 68, and 36% of adherable area, respectively, on the fabricated surface. A meticulous investigation of the cell migration in response to changes in the constrained adherable area of the nanotopographic surface showed 1.4-, 1.5-, and 1.6-fold increase in migration speeds and a 1.4-, 2-, and 2.5-fold decrease in the number of focal adhesions as the adherable area was decreased to 86, 68, and 36%, respectively. Furthermore, a strong activation of FAK/Rac1 signaling was observed to be involved in the promoted cell migration. These results suggest that the reduced adherable area promotes cell migration through decreasing the FA formation, which in turn upregulates FAK/Rac1 activation. The findings in this study can be utilized to control the cell migration behaviors, which is a powerful tool in the research fields involving cell migration such as promoting wound healing and tissue repair.

Mesoporous carbon-supported Pd nanoparticles with high specific surface area for cyclohexene hydrogenation: Outstanding catalytic activity of NaOH-treated catalysts

NASA Astrophysics Data System (ADS)

Puskás, R.; Varga, T.; Grósz, A.; Sápi, A.; Oszkó, A.; Kukovecz, Á.; Kónya, Z.

2016-06-01

Extremely high specific surface area mesoporous carbon-supported Pd nanoparticle catalysts were prepared with both impregnation and polyol-based sol methods. The silica template used for the synthesis of mesoporous carbon was removed by both NaOH and HF etching. Pd/mesoporous carbon catalysts synthesized with the impregnation method has as high specific surface area as 2250 m2/g. In case of NaOH-etched impregnated samples, the turnover frequency of cyclohexene hydrogenation to cyclohexane at 313 K was obtained 14 molecules • site- 1 • s- 1. The specific surface area of HF-etched samples was higher compared to NaOH-etched samples. However, catalytic activity was 3-6 times higher on NaOH-etched samples compared to HF-etched samples, which can be attributed to the presence of sodium and surface hydroxylgroups of the catalysts etched with NaOH solution.

Using the 3D active fault model to estimate the surface deformation, a study on HsinChu area, Taiwan.

NASA Astrophysics Data System (ADS)

Lin, Y. K.; Ke, M. C.; Ke, S. S.

2016-12-01

An active fault is commonly considered to be active if they have moved one or more times in the last 10,000 years and likely to have another earthquake sometime in the future. The relationship between the fault reactivation and the surface deformation after the Chi-Chi earthquake (M=7.2) in 1999 has been concerned up to now. According to the investigations of well-known disastrous earthquakes in recent years, indicated that surface deformation is controlled by the 3D fault geometric shape. Because the surface deformation may cause dangerous damage to critical infrastructures, buildings, roads, power, water and gas lines etc. Therefore it's very important to make pre-disaster risk assessment via the 3D active fault model to decrease serious economic losses, people injuries and deaths caused by large earthquake. The approaches to build up the 3D active fault model can be categorized as (1) field investigation (2) digitized profile data and (3) build the 3D modeling. In this research, we tracked the location of the fault scarp in the field first, then combined the seismic profiles (had been balanced) and historical earthquake data to build the underground fault plane model by using SKUA-GOCAD program. Finally compared the results come from trishear model (written by Richard W. Allmendinger, 2012) and PFC-3D program (Itasca) and got the calculated range of the deformation area. By analysis of the surface deformation area made from Hsin-Chu Fault, we concluded the result the damage zone is approaching 68 286m, the magnitude is 6.43, the offset is 0.6m. base on that to estimate the population casualties, building damage by the M=6.43 earthquake in Hsin-Chu area, Taiwan. In the future, in order to be applied accurately on earthquake disaster prevention, we need to consider further the groundwater effect and the soil structure interaction inducing by faulting.

Effect of surface area and chemisorbed oxygen on the SO2 adsorption capacity of activated char

USGS Publications Warehouse

Lizzio, A.A.; DeBarr, J.A.

1996-01-01

The objective of this study was to determine whether activated char produced from Illinois coal could be used effectively to remove sulfur dioxide from coal combustion flue gas. Chars were prepared from a high-volatile Illinois bituminous coal under a wide range of pyrolysis and activation conditions. A novel char preparation technique was developed to prepare chars with SO2 adsorption capacities significantly greater than that of a commercial activated carbon. In general, there was no correlation between SO2 adsorption capacity and surface area. Temperature-programmed desorption (TPD) was used to determine the nature and extent of carbon-oxygen (C-O) complexes formed on the char surface. TPD data revealed that SO2 adsorption was inversely proportional to the amount of C-O complex. The formation of a stable C-O complex during char preparation may have served only to occupy carbon sites that were otherwise reactive towards SO2 adsorption. A fleeting C(O) complex formed during SO2 adsorption is postulated to be the reaction intermediate necessary for conversion of SO2 to H2SO4. Copyright ?? 1996 Elsevier Science Ltd.

The Investigation of a Sinkhole Area in Germany by Near-Surface Active Seismic Tomography

NASA Astrophysics Data System (ADS)

Tschache, S.; Becker, D.; Wadas, S. H.; Polom, U.; Krawczyk, C. M.

2017-12-01

In November 2010, a 30 m wide and 17 m deep sinkhole occurred in a residential area of Schmalkalden, Germany, which fortunately did not harm humans, but led to damage of buildings and property. Subsequent geoscientific investigations showed that the collapse was naturally caused by the subrosion of sulfates in a depth of about 80 m. In 2012, an early warning system was established including 3C borehole geophones deployed in 50 m depth around the backfilled sinkhole. During the acquisition of two shallow 2D shear wave seismic profiles, the signals generated by a micro-vibrator at the surface were additionally recorded by the four borehole geophones of the early warning system and a VSP probe in a fifth borehole. The travel time analysis of the direct arrivals enhanced the understanding of wave propagation in the area. Seismic velocity anomalies were detected and related to structural seismic images of the 2D profiles. Due to the promising first results, the experiment was further extended by distributing vibration points throughout the whole area around the sinkhole. This time, micro-vibrators for P- and S-wave generation were used. The signals were recorded by the borehole geophones and temporary installed seismometers at surface positions close to the boreholes. The travel times and signal attenuations are evaluated to detect potential instable zones. Furthermore, array analyses are performed. The first results reveal features in the active tomography datasets consistent with structures observed in the 2D seismic images. The advantages of the presented method are the low effort and good repeatability due to the permanently installed borehole geophones. It has the potential to determine P-wave and S-wave velocities in 3D. It supports the interpretation of established investigation methods as 2D surface seismics and VSP. In our further research we propose to evaluate the suitability of the method for the time lapse monitoring of changes in the seismic wave

The surface area of soil organic matter

USGS Publications Warehouse

Chiou, C.T.; Lee, J.-F.; Boyd, S.A.

1990-01-01

The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.

Comparison of Surface and Column Variations of CO2 Over Urban Areas for Future Active Remote CO2 Sensors

NASA Technical Reports Server (NTRS)

Choi, Yonghoon; Yang, Melissa; Kooi, Susan; Browell, Edward

2015-01-01

High resolution in-situ CO2 measurements were recorded onboard the NASA P-3B during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) Field Campaign, to investigate the ability of space-based observations to accurately assess near surface conditions related to air quality. This campaign includes, Washington DC/Baltimore, MD (July 2011), San Joaquin Valley, CA (January - February 2013), Houston, TX (September 2013), and Denver, CO (July-August 2014). Each of these campaigns consisted of missed approaches and approximately two hundred vertical soundings of CO2 within the lower troposphere (surface to about 5 km). In this study, surface (0 - 1 km) and column-averaged (0 - 3.5 km) CO2 mixing ratio values from the vertical soundings in the four geographically different urban areas are used to investigate the temporal and spatial variability of CO2 within the different urban atmospheric emission environments. Tracers such as CO, CH2O, NOx, and NMHCs are used to identify the source of CO2 variations in the urban sites. Additionally, we apply nominal CO2 column weighting functions for potential future active remote CO2 sensors operating in the 1.57-microns and 2.05-microns measurement regions to convert the in situ CO2 vertical mixing ratio profiles to variations in CO2 column optical depths, which is what the active remote sensors actually measure. Using statistics calculated from the optical depths at each urban site measured during the DISCOVER-AQ field campaign and for each nominal weighting function, we investigate the natural variability of CO2 columns in the lower troposphere; relate the CO2 column variability to the urban surface emissions; and show the measurement requirements for the future ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) in the continental U.S. urban areas.

Ultrahigh surface area carbon from carbonated beverages: Combining self-templating process and in situ activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua

Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy coversmore » various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, and Fanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.« less

Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua

Ultrahigh surface area carbons (USACs, e.g., >2000 m 2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m 2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. Thismore » strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m 2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g -1) even at a scan rate of 1000 mV s -1. Thus, a simple and efficient strategy to USACs has been presented.« less

Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

DOE PAGES

Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; ...

2015-05-11

Ultrahigh surface area carbons (USACs, e.g., >2000 m 2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m 2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. Thismore » strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m 2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g -1) even at a scan rate of 1000 mV s -1. Thus, a simple and efficient strategy to USACs has been presented.« less

Estimating the surface area of birds: using the homing pigeon (Columba livia) as a model.

PubMed

Perez, Cristina R; Moye, John K; Pritsos, Chris A

2014-05-08

Estimation of the surface area of the avian body is valuable for thermoregulation and metabolism studies as well as for assessing exposure to oil and other surface-active organic pollutants from a spill. The use of frozen carcasses for surface area estimations prevents the ability to modify the posture of the bird. The surface area of six live homing pigeons in the fully extended flight position was estimated using a noninvasive method. An equation was derived to estimate the total surface area of a pigeon based on its body weight. A pigeon's surface area in the fully extended flight position is approximately 4 times larger than the surface area of a pigeon in the perching position. The surface area of a bird is dependent on its physical position, and, therefore, the fully extended flight position exhibits the maximum area of a bird and should be considered the true surface area of a bird. © 2014. Published by The Company of Biologists Ltd | Biology Open.

Guard cells elongate: relationship of volume and surface area during stomatal movement.

PubMed

Meckel, Tobias; Gall, Lars; Semrau, Stefan; Homann, Ulrike; Thiel, Gerhard

2007-02-01

Stomata in the epidermis of photosynthetically active plant organs are formed by pairs of guard cells, which create a pore, to facilitate CO2 and water exchange with the environment. To control this gas exchange, guard cells actively change their volume and, consequently, surface area to alter the aperture of the stomatal pore. Due to the limited elasticity of the plasma membrane, such changes in surface area require an exocytic addition or endocytic retrieval of membrane during stomatal movement. Using confocal microscopic data, we have reconstructed detailed three-dimensional models of open and closed stomata to precisely quantify the necessary area to be exo- and endocytosed by the guard cells. Images were obtained under a strong emphasis on a precise calibration of the method and by avoiding unphysiological osmotical imbalance, and hence osmocytosis. The data reveal that guard cells of Vicia faba L., whose aperture increases by 111.89+/-22.39%, increase in volume and surface area by 24.82+/-6.26% and 14.99+/-2.62%, respectively. In addition, the precise volume to surface area relationship allows quantitative modeling of the three-dimensional changes. While the major volume change is caused by a slight increase in the cross section of the cells, an elongation of the guard cells achieves the main aperture change.

High surface area LaMnO3 nanoparticles enhancing electrochemical catalytic activity for rechargeable lithium-air batteries

NASA Astrophysics Data System (ADS)

Li, Chuanhua; Yu, Zhiyong; Liu, Hanxing; Chen, Kang

2018-02-01

To improve sluggish kinetics of ORR and OER (oxygen reduction and evolution reaction) on the air electrode, the high surface area LaMnO3 nanoparticle catalysts were synthesized by sol-gel method. The specific surface area of as-synthesized pure phase LaMnO3 nanoparticles is 21.21 m2 g-1. The onset potential of high surface area LaMnO3 in alkaline solution is -0.0202 V which is comparable to commercial Pt/C. When the assembled high surface area LaMnO3-based lithium-air batteries were measured at 100 mA g-1, the initial discharge specific capacity could reach 6851.9 mA h g-1(carbon). In addition, lithium-oxygen batteries including high surface area LaMnO3 catalysts could be cycled for 52 cycles at 200 mA g-1 under a limited discharge-charge depth of 500 mA h gcarbon-1.

Surface area-volume ratios in insects.

PubMed

Kühsel, Sara; Brückner, Adrian; Schmelzle, Sebastian; Heethoff, Michael; Blüthgen, Nico

2017-10-01

Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area-volume (SA/V) ratios for the first time using 3D surface models based on a structured light scanning method for 126 species of pollinating insects from 4 orders (Diptera, Hymenoptera, Lepidoptera, and Coleoptera). Water loss of 67 species was measured gravimetrically at very dry conditions for 2 h at 15 and 30 °C to demonstrate the applicability of the new 3D surface measurements and relevance for predicting the performance of insects. Quantified SA/V ratios significantly explained the variation in water loss across species, both directly or after accounting for isometric scaling (residuals of the SA/V ∼ mass 2/3 relationship). Small insects with a proportionally larger surface area had the highest water loss rates. Surface scans of insects to quantify allometric SA/V ratios thus provide a promising method to predict physiological responses, improving the potential of body mass isometry alone that assume geometric similarity. © 2016 Institute of Zoology, Chinese Academy of Sciences.

fMRI evidence for areas that process surface gloss in the human visual cortex

PubMed Central

Sun, Hua-Chun; Ban, Hiroshi; Di Luca, Massimiliano; Welchman, Andrew E.

2015-01-01

Surface gloss is an important cue to the material properties of objects. Recent progress in the study of macaque’s brain has increased our understating of the areas involved in processing information about gloss, however the homologies with the human brain are not yet fully understood. Here we used human functional magnetic resonance imaging (fMRI) measurements to localize brain areas preferentially responding to glossy objects. We measured cortical activity for thirty-two rendered three-dimensional objects that had either Lambertian or specular surface properties. To control for differences in image structure, we overlaid a grid on the images and scrambled its cells. We found activations related to gloss in the posterior fusiform sulcus (pFs) and in area V3B/KO. Subsequent analysis with Granger causality mapping indicated that V3B/KO processes gloss information differently than pFs. Our results identify a small network of mid-level visual areas whose activity may be important in supporting the perception of surface gloss. PMID:25490434

Parallel, stochastic measurement of molecular surface area.

PubMed

Juba, Derek; Varshney, Amitabh

2008-08-01

Biochemists often wish to compute surface areas of proteins. A variety of algorithms have been developed for this task, but they are designed for traditional single-processor architectures. The current trend in computer hardware is towards increasingly parallel architectures for which these algorithms are not well suited. We describe a parallel, stochastic algorithm for molecular surface area computation that maps well to the emerging multi-core architectures. Our algorithm is also progressive, providing a rough estimate of surface area immediately and refining this estimate as time goes on. Furthermore, the algorithm generates points on the molecular surface which can be used for point-based rendering. We demonstrate a GPU implementation of our algorithm and show that it compares favorably with several existing molecular surface computation programs, giving fast estimates of the molecular surface area with good accuracy.

Calculating landscape surface area from digital elevation models

Treesearch

Jeff S. Jenness

2004-01-01

There are many reasons to want to know the true surface area of the landscape, especially in landscape analysis and studies of wildlife habitat. Surface area provides a better estimate of the land area available to an animal than planimetric area, and the ratio of this surface area to planimetric area provides a useful measure of topographic roughness of the landscape...

Surface activity of lipid extract surfactant in relation to film area compression and collapse.

PubMed

Schürch, S; Schürch, D; Curstedt, T; Robertson, B

1994-08-01

The physical properties of modified porcine surfactant (Curosurf), isolated from minced lungs by extraction with chloroform-methanol and further purified by liquid-gel chromatography, were investigated with the captive bubble technique. Bubble size, and thus the surface tension of an insoluble film at the bubble surface, is altered by changing the pressure within the closed bubble chamber. The film surface tension and area are determined from the shape (height and diameter) of the bubble. Adsorption of fresh Curosurf is characterized by stepwise decreases in surface tension, which can easily be observed by sudden quick movements of the bubble apex. These "adsorption clicks" imply a cooperative movement of large collective units of molecules, approximately 10(14) (corresponding to approximately 120 ng of phospholipid) or approximately 10(18) molecules/m2, into the interface during adsorption. Films formed in this manner are already highly enriched in dipalmitoyl phosphatidylcholine, as seen by the extremely low compressibility, close to that of dipalmitoyl phosphatidylcholine. Near-zero minimum tensions are obtained, even at phospholipid concentrations as low as 50 micrograms/ml. During dynamic cycling (20-50 cycles/min), low minimum surface tensions, good film stability, low compressibility, and maximum surface tensions between 30 and 40 mN/m are possible only if the films are not overcompressed near zero surface tension; i.e., the overall film area compression should not substantially exceed 30%.

Superwetting and aptamer functionalized shrink-induced high surface area electrochemical sensors.

PubMed

Hauke, A; Kumar, L S Selva; Kim, M Y; Pegan, J; Khine, M; Li, H; Plaxco, K W; Heikenfeld, J

2017-08-15

Electrochemical sensing is moving to the forefront of point-of-care and wearable molecular sensing technologies due to the ability to miniaturize the required equipment, a critical advantage over optical methods in this field. Electrochemical sensors that employ roughness to increase their microscopic surface area offer a strategy to combatting the loss in signal associated with the loss of macroscopic surface area upon miniaturization. A simple, low-cost method of creating such roughness has emerged with the development of shrink-induced high surface area electrodes. Building on this approach, we demonstrate here a greater than 12-fold enhancement in electrochemically active surface area over conventional electrodes of equivalent on-chip footprint areas. This two-fold improvement on previous performance is obtained via the creation of a superwetting surface condition facilitated by a dissolvable polymer coating. As a test bed to illustrate the utility of this approach, we further show that electrochemical aptamer-based sensors exhibit exceptional signal strength (signal-to-noise) and excellent signal gain (relative change in signal upon target binding) when deployed on these shrink electrodes. Indeed, the observed 330% gain we observe for a kanamycin sensor is 2-fold greater than that seen on planar gold electrodes. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of retinal surface area.

PubMed

Nagra, Manbir; Gilmartin, Bernard; Thai, Ngoc Jade; Logan, Nicola S

2017-09-01

Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye in vivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25 ± 6.06 years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50 ± 4.03D and mean axial length (AL) 24.51 ± 1.57 mm. Mean TSA and RSA for the RE were 2058 ± 189 and 1363 ± 160 mm 2 , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P < 0.01) which, contrasted with ST (365 ± 43 mm 2 ), was significant for IT (340 ± 40 mm 2 P < 0.01), SN (337 ± 40 mm 2 P < 0.01) and IN (321 ± 39 mm 2 P < 0.01) quadrants. For all quadrants, QRSA was significantly correlated with AL (P < 0.01) and exhibited

Size-dependent proinflammatory effects of ultrafine polystyrene particles: a role for surface area and oxidative stress in the enhanced activity of ultrafines.

PubMed

Brown, D M; Wilson, M R; MacNee, W; Stone, V; Donaldson, K

2001-09-15

Studies into the effects of ultrafine particles in the lung have shown adverse effects considered to be due in part to the particle size. Air pollution particles (PM(10)) are associated with exacerbations of respiratory disease and deaths from cardiovascular causes in epidemiological studies and the ultrafine fraction of PM(10) has been hypothesized to play an important role. The aim of the present study was to investigate proinflammatory responses to various sizes of polystyrene particles as a simple model of particles of varying size including ultrafine. In the animal model, we demonstrated that there was a significantly greater neutrophil influx into the rat lung after instillation of 64-nm polystyrene particles compared with 202- and 535-nm particles and this was mirrored in other parameters of lung inflammation, such as increased protein and lactate dehydrogenase in bronchoalveolar lavage. When surface area instilled was plotted against inflammation, these two variables were directly proportional and the line passed through zero. This suggests that surface area drives inflammation in the short term and that ultrafine particles cause a greater inflammatory response because of the greater surface area they possess. In vitro, we measured the changes in intracellular calcium concentration in mono mac 6 cells in view of the potential role of calcium as a signaling molecule. Calcium changes after particle exposure may be important in leading to proinflammatory gene expression such as chemokines. We demonstrated that only ultrafine polystyrene particles induced a significant increase in cytosolic calcium ion concentration. Experiments using dichlorofluorescin diacetate demonstrated greater oxidant activity of the ultrafine particles, which may explain their activity in these assays. There were significant increases in IL-8 gene expression in A549 epithelial cells after treatment with the ultrafine particles but not particles of other sizes. These findings suggest

Active microwave remote sensing research program plan. Recommendations of the Earth Resources Synthetic Aperture Radar Task Force. [application areas: vegetation canopies, surface water, surface morphology, rocks and soils, and man-made structures

NASA Technical Reports Server (NTRS)

1980-01-01

A research program plan developed by the Office of Space and Terrestrial Applications to provide guidelines for a concentrated effort to improve the understanding of the measurement capabilities of active microwave imaging sensors, and to define the role of such sensors in future Earth observations programs is outlined. The focus of the planned activities is on renewable and non-renewable resources. Five general application areas are addressed: (1) vegetation canopies, (2) surface water, (3) surface morphology, (4) rocks and soils, and (5) man-made structures. Research tasks are described which, when accomplished, will clearly establish the measurement capabilities in each area, and provide the theoretical and empirical results needed to specify and justify satellite systems using imaging radar sensors for global observations.

High surface area calcite

NASA Astrophysics Data System (ADS)

Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

2013-05-01

Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

Explosively activated egress area

NASA Technical Reports Server (NTRS)

Bement, L. J.; Bailey, J. W. (Inventor)

1983-01-01

A lightweight, add on structure which employs linear shaped pyrotechnic charges to smoothly cut an airframe along an egress area periphery is provided. It compromises reaction surfaces attached to the exterior surface of the airframe's skin and is designed to restrict the skin deflection. That portion of the airframe within the egress area periphery is jettisoned. Retention surfaces and sealing walls are attached to the interior surface of the airframe's skin and are designed to shield the interior of the aircraft during detonation of the pyrotechnic charges.

High Surface Area Dendrite Nanoelectrodes for Electrochemistry

NASA Astrophysics Data System (ADS)

Nesbitt, Nathan; Glover, Jennifer; Goyal, Saurabh; Simidjiysky, Svetoslav; Naughton, Michael

2014-03-01

Solution-based electrodeposition of metal using a low ion concentration, surface passivation agents, and/or electrochemical crystal conditioning has allowed for the formation of high surface area metal electrodes, useful for Raman spectroscopy and electrochemical sensors. Additionally, high frequency electrical oscillations have been used to electrically connect co-planar electrodes, a process called directed electrochemical nanowire assembly (DENA). These approaches aim to control the crystal face that metal atoms in solution will nucleate onto, thus causing anisotropic growth of metal crystals. However, DENA has not been used to create high surface area electrodes, and no study has been conducted on the effect of micron-scale surface topography on the initial nucleation of metal crystals on the electrode surface. When DENA is used to create a high surface area electrode, such a texture has a strong impact on the subsequent topography of the three dimensional dendritic structures by limiting the areal density of crystals on the electrode surface. Such structures both demonstrate unique physics concerning the nucleation of metal dendrites, and offer a unique and highly facile fabrication method of high surface area electrodes, useful for chemical and biological sensing. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. (DGE-1258923).

High surface area, low weight composite nickel fiber electrodes

NASA Technical Reports Server (NTRS)

Johnson, Bradley A.; Ferro, Richard E.; Swain, Greg M.; Tatarchuk, Bruce J.

1993-01-01

The energy density and power density of light weight aerospace batteries utilizing the nickel oxide electrode are often limited by the microstructures of both the collector and the resulting active deposit in/on the collector. Heretofore, these two microstructures were intimately linked to one another by the materials used to prepare the collector grid as well as the methods and conditions used to deposit the active material. Significant weight and performance advantages were demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of ca. 28-32 microns diameter. Work in our laboratory investigated the potential performance advantages offered by nickel fiber composite electrodes containing a mixture of fibers as small as 2 microns diameter (Available from Memtec America Corporation). These electrode collectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinner layer of active material. Performance data and advantages of these thin layer structures are presented. Attributes and limitations of their electrode microstructure to independently control void volume, pore structure of the Ni(OH)2 deposition, and resulting electrical properties are discussed.

Hand burns surface area: A rule of thumb.

PubMed

Dargan, Dallan; Mandal, Anirban; Shokrollahi, Kayvan

2018-08-01

Rapid estimation of acute hand burns is important for communication, standardisation of assessment, rehabilitation and research. Use of an individual's own thumbprint area as a fraction of their total hand surface area was evaluated to assess potential utility in hand burn evaluation. Ten health professionals used an ink-covered dominant thumb pulp to cover the surfaces of their own non-dominant hand using the contralateral thumb. Thumbprints were assessed on the web spaces, sides of digits and dorsum and palm beyond the distal wrist crease. Hand surface area was estimated using the Banerjee and Sen method, and thumbprint ellipse area calculated to assess correlation. Mean estimated total hand surface area was 390.0cm 2 ±SD 51.5 (328.3-469.0), mean thumbprint ellipse area was 5.5cm 2 ±SD 1.3 (3.7-8.4), and mean estimated print number was 73.5±SD 11.0 (range 53.1-87.8, 95% CI 6.8). The mean observed number of thumbprints on one hand was 80.1±SD 5.9 (range 70.0-88.0, 95% CI 3.7), χ 2 =0.009. The combined mean of digital prints was 42, comprising a mean of two prints each on volar, dorsal, radial and ulnar digit surfaces, except volar middle and ring (3 prints each). Palmar prints were 15 (11-19), dorsal 15 (11-19), ulnar palm border 3, first web space 2, and second, third and fourth web spaces one each. Using the surface of the palm alone, excluding digits, as 0.5% of total body surface area, the area of one thumbprint was approximated as 1/30th of 1%. We have demonstrated how thumbprint area serves as a simple method for evaluating hand burn surface area. Copyright © 2018 Elsevier Ltd and ISBI. All rights reserved.

High surface area electrodes by template-free self-assembled hierarchical porous gold architecture.

PubMed

Morag, Ahiud; Golub, Tatiana; Becker, James; Jelinek, Raz

2016-06-15

The electrode active surface area is a crucial determinant in many electrochemical applications and devices. Porous metal substrates have been employed in electrode design, however construction of such materials generally involves multistep processes, generating in many instances electrodes exhibiting incomplete access to internal pore surfaces. Here we describe fabrication of electrodes comprising hierarchical, nano-to-microscale porous gold matrix, synthesized through spontaneous crystallization of gold thiocyanate in water. Cyclic voltammetry analysis revealed that the specific surface area of the conductive nanoporous Au microwires was very high and depended only upon the amount of gold used, not electrode areas or geometries. Application of the electrode in a pseudo-capacitor device is presented. Copyright © 2016 Elsevier Inc. All rights reserved.

Flexible shrink-induced high surface area electrodes for electrochemiluminescent sensing.

PubMed

Pegan, Jonathan D; Ho, Adrienne Y; Bachman, Mark; Khine, Michelle

2013-11-07

Photolithographically defined metallic thin film on commodity shrink-wrap is leveraged to create robust electrodes. By thermally shrinking the film, electrodes are reduced by 20× in footprint for improved resolution and conductivity with >600% enhancements in electrochemically active surface area; as electrochemiluminescent sensors, they demonstrate improved limits of detection.

50 CFR 218.180 - Specified activity and specified geographical area and effective dates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Mission Activities in the Naval Surface Warfare Center Panama City Division § 218.180 Specified activity... operations) W-151 (includes Panama City Operating Area), W-155 (includes Pensacola Operating Area), and W-470...

50 CFR 218.180 - Specified activity and specified geographical area and effective dates.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Mission Activities in the Naval Surface Warfare Center Panama City Division § 218.180 Specified activity... operations) W-151 (includes Panama City Operating Area), W-155 (includes Pensacola Operating Area), and W-470...

Adsorbed Natural Gas Storage in Optimized High Surface Area Microporous Carbon

NASA Astrophysics Data System (ADS)

Romanos, Jimmy; Rash, Tyler; Nordwald, Erik; Shocklee, Joshua Shawn; Wexler, Carlos; Pfeifer, Peter

2011-03-01

Adsorbed natural gas (ANG) is an attractive alternative technology to compressed natural gas (CNG) or liquefied natural gas (LNG) for the efficient storage of natural gas, in particular for vehicular applications. In adsorbants engineered to have pores of a few molecular diameters, a strong van der Walls force allows reversible physisorption of methane at low pressures and room temperature. Activated carbons were optimized for storage by varying KOH:C ratio and activation temperature. We also consider the effect of mechanical compression of powders to further enhance the volumetric storage capacity. We will present standard porous material characterization (BET surface area and pore-size distribution from subcritical N2 adsorption) and methane isotherms up to 250 bar at 293K. At sufficiently high pressure, specific surface area, methane binding energy and film density can be extracted from supercritical methane adsorption isotherms. Research supported by the California Energy Commission (500-08-022).

Quantifying object and material surface areas in residences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hodgson, Alfred T.; Ming, Katherine Y.; Singer, Brett C.

2005-01-05

The dynamic behavior of volatile organic compounds (VOCs) in indoor environments depends, in part, on sorptive interactions between VOCs in the gas phase and material surfaces. Since information on the types and quantities of interior material surfaces is not generally available, this pilot-scale study was conducted in occupied residences to develop and demonstrate a method for quantifying surface areas of objects and materials in rooms. Access to 33 rooms in nine residences consisting of bathrooms, bedroom/offices and common areas was solicited from among research group members living in the East San Francisco Bay Area. A systematic approach was implemented formore » measuring rooms and objects from 300 cm{sup 2} and larger. The ventilated air volumes of the rooms were estimated and surface area-to-volume ratios were calculated for objects and materials, each segregated into 20 or more categories. Total surface area-to-volume ratios also were determined for each room. The bathrooms had the highest total surface area-to-volume ratios. Bedrooms generally had higher ratios than common areas consisting of kitchens, living/dining rooms and transitional rooms. Total surface area-to-volume ratios for the 12 bedrooms ranged between 2.3 and 4.7 m{sup 2} m{sup -3}. The importance of individual objects and materials with respect to sorption will depend upon the sorption coefficients for the various VOC/materials combinations. When combined, the highly permeable material categories, which may contribute to significant interactions, had a median ratio of about 0.5 m{sup 2} m{sup -3} for all three types of rooms.« less

Predicting the quality of powders for inhalation from surface energy and area.

PubMed

Cline, David; Dalby, Richard

2002-09-01

To correlate the surface energy of active and carrier components in an aerosol powder to in vitro performance of a passive dry powder inhaler. Inverse gas chromatography (IGC) was used to assess the surface energy of active (albuterol and ipratropium bromide) and carrier (lactose monohydrate, trehalose dihydrate and mannitol) components of a dry powder inhaler formulation. Blends (1%w/w) of drug and carrier were prepared and evaluated for dry powder inhaler performance by cascade impaction. The formulations were tested with either of two passive dry powder inhalers, Rotahaler (GlaxoSmithKline) or Handihaler (Boehringer Ingelheim). In vitro performance of the powder blends was strongly correlated to surface energy interaction between active and carrier components. Plotting fine particle fraction vs. surface energy interaction yielded an R2 value of 0.9283. Increasing surface energy interaction between drug and carrier resulted in greater fine particle fraction of drug. A convincing relationship, potentially useful for rapid formulation design and screening, was found between the surface energy and area parameters derived from IGC and dry powder inhaler performance.

Mechanics of active surfaces

NASA Astrophysics Data System (ADS)

Salbreux, Guillaume; Jülicher, Frank

2017-09-01

We derive a fully covariant theory of the mechanics of active surfaces. This theory provides a framework for the study of active biological or chemical processes at surfaces, such as the cell cortex, the mechanics of epithelial tissues, or reconstituted active systems on surfaces. We introduce forces and torques acting on a surface, and derive the associated force balance conditions. We show that surfaces with in-plane rotational symmetry can have broken up-down, chiral, or planar-chiral symmetry. We discuss the rate of entropy production in the surface and write linear constitutive relations that satisfy the Onsager relations. We show that the bending modulus, the spontaneous curvature, and the surface tension of a passive surface are renormalized by active terms. Finally, we identify active terms which are not found in a passive theory and discuss examples of shape instabilities that are related to active processes in the surface.

Volumes and surface areas of pendular rings

USGS Publications Warehouse

Rose, W.

1958-01-01

A packing of spheres is taken as a suitable model of porous media. The packing may be regular and the sphere size may be uniform, but in general, both should be random. Approximations are developed to give the volumes and surface areas of pendular rings that exist at points of sphere contact. From these, the total free volume and interfacial specific surface area are derived as expressive of the textural character of the packing. It was found that the log-log plot of volumes and surface areas of pendular rings vary linearly with the angle made by the line joining the sphere centers and the line from the center of the largest sphere to the closest edge of the pendular ring. The relationship, moreover, was found not to be very sensitive to variation in the size ratio of the spheres in contact. It also was found that the addition of pendular ring material to various sphere packings results in an unexpected decrease in the surface area of the boundaries that confine the resulting pore space. ?? 1958 The American Institute of Physics.

Monitoring the Presence of 13 Active Compounds in Surface Water Collected from Rural Areas in Northwestern Spain

PubMed Central

Iglesias, Alejandra; Nebot, Carolina; Vázquez, Beatriz I.; Coronel-Olivares, Claudia; Franco Abuín, Carlos M.; Cepeda, Alberto

2014-01-01

Drug residues are considered environmental contaminants, and their occurrence has recently become a matter of concern. Analytical methods and monitoring systems are therefore required to control the continuous input of these drug residues into the environment. This article presents a suitable HPLC-ESI-MS/MS method for the simultaneous extraction, detection and quantification of residues of 13 drugs (antimicrobials, glucocorticosteroids, anti-inflammatories, anti-hypertensives, anti-cancer drugs and triphenylmethane dyes) in surface water. A monitoring study with 549 water samples was carried out in northwestern Spain to detect the presence of drug residues over two sampling periods during 2010, 2011 and 2012. Samples were collected from rural areas with and without farming activity and from urban areas. The 13 analytes were detected, and 18% of the samples collected showed positive results for the presence of at least one analyte. More collection sites were located in rural areas than in urban areas. However, more positive samples with higher concentrations and a larger number of analytes were detected in samples collected from sites located after the discharge of a WWTP. Results indicated that the WWTPs seems to act as a concentration point. Positive samples were also detected at a site located near a drinking water treatment plant. PMID:24837665

Monitoring the presence of 13 active compounds in surface water collected from rural areas in northwestern Spain.

PubMed

Iglesias, Alejandra; Nebot, Carolina; Vázquez, Beatriz I; Coronel-Olivares, Claudia; Abuín, Carlos M Franco; Cepeda, Alberto

2014-05-15

Drug residues are considered environmental contaminants, and their occurrence has recently become a matter of concern. Analytical methods and monitoring systems are therefore required to control the continuous input of these drug residues into the environment. This article presents a suitable HPLC-ESI-MS/MS method for the simultaneous extraction, detection and quantification of residues of 13 drugs (antimicrobials, glucocorticosteroids, anti-inflammatories, anti-hypertensives, anti-cancer drugs and triphenylmethane dyes) in surface water. A monitoring study with 549 water samples was carried out in northwestern Spain to detect the presence of drug residues over two sampling periods during 2010, 2011 and 2012. Samples were collected from rural areas with and without farming activity and from urban areas. The 13 analytes were detected, and 18% of the samples collected showed positive results for the presence of at least one analyte. More collection sites were located in rural areas than in urban areas. However, more positive samples with higher concentrations and a larger number of analytes were detected in samples collected from sites located after the discharge of a WWTP. Results indicated that the WWTPs seems to act as a concentration point. Positive samples were also detected at a site located near a drinking water treatment plant.

Correlation of lung surface area to apoptosis and proliferation in human emphysema.

PubMed

Imai, K; Mercer, B A; Schulman, L L; Sonett, J R; D'Armiento, J M

2005-02-01

Pulmonary emphysema is associated with alterations in matrix proteins and protease activity. These alterations may be linked to programmed cell death by apoptosis, potentially influencing lung architecture and lung function. To evaluate apoptosis in emphysema, lung tissue was analysed from 10 emphysema patients and six individuals without emphysema (normal). Morphological analysis revealed alveolar cells in emphysematous lungs with convoluted nuclei characteristic of apoptosis. DNA fragmentation was detected using terminal deoxynucleotide transferase-mediated dUTP nick-end labelling (TUNEL) and gel electrophoresis. TUNEL revealed higher apoptosis in emphysematous than normal lungs. Markers of apoptosis, including active caspase-3, proteolytic fragment of poly (ADP-ribose) polymerase, Bax and Bad, were detected in emphysematous lungs. Linear regression showed that apoptosis was inversely correlated with surface area. Emphysematous lungs demonstrated lower surface areas and increased cell proliferation. There was no correlation between apoptosis and proliferation, suggesting that, although both events increase during emphysema, they are not in equilibrium, potentially contributing to reduced lung surface area. In summary, cell-based mechanisms associated with emphysematous parenchymal damage include increased apoptosis and cell proliferation. Apoptosis correlated with airspace enlargement, supporting epidemiological evidence of the progressive nature of emphysema. These data extend the understanding of cell dynamics and structural changes within the lung during emphysema pathogenesis.

Surface areas of fractally rough particles studied by scattering

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Schaefer, Dale W.; Smith, Douglas M.; Ross, Steven B.; Le Méhauté, Alain; Spooner, Steven

1989-05-01

The small-angle scattering from fractally rough surfaces has the potential to give information on the surface area at a given resolution. By use of quantitative neutron and x-ray scattering, a direct comparison of surface areas of fractally rough powders was made between scattering and adsorption techniques. This study supports a recently proposed correction to the theory for scattering from fractal surfaces. In addition, the scattering data provide an independent calibration of molecular adsorbate areas.

Construction of high-energy-density supercapacitors from pine-cone-derived high-surface-area carbons.

PubMed

Karthikeyan, Kaliyappan; Amaresh, Samuthirapandiyan; Lee, Sol Nip; Sun, Xueliang; Aravindan, Vanchiappan; Lee, Young-Gi; Lee, Yun Sung

2014-05-01

Very high surface area activated carbons (AC) are synthesized from pine cone petals by a chemical activation process and subsequently evaluated as an electrode material for supercapacitor applications in a nonaqueous medium. The maximum specific surface area of ∼3950 m(2)  g(-1) is noted for the material treated with a 1:5 ratio of KOH to pine cone petals (PCC5), which is much higher than that reported for carbonaceous materials derived from various other biomass precursors. A symmetric supercapacitor is fabricated with PCC5 electrodes, and the results showed enhanced supercapacitive behavior with the highest energy density of ∼61 Wh kg(-1). Furthermore, outstanding cycling ability is evidenced for such a configuration, and ∼90 % of the initial specific capacitance after 20,000 cycles under harsh conditions was observed. This result revealed that the pine-cone-derived high-surface-area AC can be used effectively as a promising electrode material to construct high-energy-density supercapacitors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Active faulting Vs other surface displacing complex geomorphic phenomena. Case studies from a tectonically active area, Abruzzi Region, central Apennines, Italy

NASA Astrophysics Data System (ADS)

Lo Sardo, Lorenzo; Gori, Stefano; Falcucci, Emanuela; Saroli, Michele; Moro, Marco; Galadini, Fabrizio; Lancia, Michele; Fubelli, Giandomenico; Pezzo, Giuseppe

2016-04-01

How can be univocally inferred the genesis of a linear surface scarp as the result of an active and capable fault (FAC) in tectonically active regions? Or, conversely, how it is possible to exclude that a scarp is the result of a capable fault activation? Trying to unravel this open questions, we show two ambiguous case studies about the problem of the identification of active and capable faults in a tectonically active area just based on the presence of supposed fault scarps at surface. The selected cases are located in the area comprised between the Middle Aterno Valley Fault (MAVF) and the Campo Imperatore Plain (Abruzzi Region, central Apennines), nearby the epicentral area of the April 6th, 2009 L'Aquila earthquake. In particular, the two case studies analysed are located in a region characterized by a widespread Quaternary faults and by several linear scarps: the case studies of (i) Prata D'Ansidonia area and (ii) Santo Stefano di Sessanio area. To assess the origin and the state of activity of the investigated geomorphic features, we applied a classical geological and geomorphological approach, based on the analysis of the available literature, the interpretation of the aerial photographs, field surveying and classical paleoseismological approach, the latter consisting in digging excavations across the analysed scarps. These analysis were then integrated by morphometrical analyses. As for case (i), we focused on determining the geomorphic "meaning" of linear scarps carved onto fluvial-deltaic conglomerates (dated to the Early Pleistocene; Bertini and Bosi, 1993), up to 3 meters high and up to 1,5 km long, that border a narrow, elongated and flat-bottom depressions, filled by colluvial deposits. These features groove the paleo-landsurface of Valle Daria (Bosi and Bertini, 1970), wide landsurface located between Barisciano and Prata D'Ansidonia. Entwining paleoseismological trenching with geophysical analyses (GPR, ERT and microgravimetrical prospections), it

Planar fuel cell utilizing nail current collectors for increased active surface area

DOEpatents

George, Thomas J.; Meacham, G. B. Kirby

2002-03-26

A plurality of nail current collector members are useful in the gas flow passages of an electrochemical device to optimize the active surfaces of the device and to provide structural support. In addition, the thicknesses of cathode and anode layers within the electrochemical device are varied according to current flow through the device to reduce resistance and increase operating efficiency.

Planar fuel cell utilizing nail current collectors for increased active surface area

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, Thomas J.; Meacham, G.B. Kirby

1999-11-26

A plurality of nail current collector members are useful in the gas flow passages of an electrochemical device to optimize the active surfaces of the device and to provide structural support. In addition, the thicknesses of cathode and anode layers within the electrochemical device are varied according to current flow through the device to reduce resistance and increase operating efficiency.

Predicting skin deficits through surface area measurements in ear reconstruction and adult ear surface area norms.

PubMed

Yazar, Memet; Sevim, Kamuran Zeynep; Irmak, Fatih; Yazar, Sevgi Kurt; Yeşilada, Ayşin Karasoy; Karşidağğ, Semra Hacikerim; Tatlidede, Hamit Soner

2013-07-01

Ear reconstruction is one of the most challenging procedures in plastic surgery practice. Many studies and techniques have been described in the literature for carving a well-pronounced framework. However, just as important as the cartilage framework is the ample amount of delicate skin coverage of the framework. In this report, we introduce an innovative method of measuring the skin surface area of the auricle from a three-dimensional template created from the healthy ear.The study group consisted of 60 adult Turkish individuals who were randomly selected (30 men and 30 women). The participant ages ranged from 18 to 45 years (mean, 31.5 years), and they had no history of trauma or congenital anomalies. The template is created by dividing the ear into aesthetic subunits and using ImageJ software to estimate the necessary amount of total skin surface area required.Reconstruction of the auricle is a complicated process that requires experience and patience to provide the auricular details. We believe this estimate will shorten the learning curve for residents and surgeons interested in ear reconstruction and will help surgeons obtain adequate skin to drape over the well-sculpted cartilage frameworks by providing a reference list of total ear skin surface area measurements for Turkish men and women.

Experimental determination of the PTW 60019 microDiamond dosimeter active area and volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marinelli, Marco, E-mail: marco.marinelli@uniroma2

Purpose: Small field output correction factors have been studied by several research groups for the PTW 60019 microDiamond (MD) dosimeter, by comparing the response of such a device with both reference dosimeters and Monte Carlo simulations. A general good agreement is observed for field sizes down to about 1 cm. However, evident inconsistencies can be noticed when comparing some experimental results and Monte Carlo simulations obtained for smaller irradiation fields. This issue was tentatively attributed by some authors to unintentional large variations of the MD active surface area. The aim of the present study is a nondestructive experimental determination ofmore » the MD active surface area and active volume. Methods: Ten MD dosimeters, one MD prototype, and three synthetic diamond samples were investigated in the present work. 2D maps of the MD response were recorded under scanned soft x-ray microbeam irradiation, leading to an experimental determination of the device active surface area. Profiles of the device responses were measured as well. In order to evaluate the MD active volume, the thickness of the diamond sensing layer was independently evaluated by capacitance measurements and alpha particle detection experiments. The MD sensitivity, measured at the PTW calibration laboratory, was also used to calculate the device active volume thickness. Results: An average active surface area diameter of (2.19 ± 0.02) mm was evaluated by 2D maps and response profiles of all the MDs. Average active volume thicknesses of (1.01 ± 0.13) μm and (0.97 ± 0.14) μm were derived by capacitance and sensitivity measurements, respectively. The obtained results are well in agreement with the nominal values reported in the manufacturer dosimeter specifications. A homogeneous response was observed over the whole device active area. Besides the one from the device active volume, no contributions from other components of the housing nor from encapsulation materials were

Dye adsorption onto activated carbons from tyre rubber waste using surface coverage analysis.

PubMed

Mui, Edward L K; Cheung, W H; Valix, Marjorie; McKay, Gordon

2010-07-15

Two types of activated carbons from tyre char (with or without sulphuric acid treatment) were produced via carbon dioxide activation with BET surface areas in the range 59-1118 m(2)/g. Other characterisation tests include micropore and mesopore surface areas and volumes, pH, and elemental compositions, particularly heteroatoms such as nitrogen and sulphur. They were correlated to the adsorption capacity which were in the range of 0.45-0.71 mmol/g (untreated) and 0.62-0.84 mmol/g (acid-treated) for Acid Blue 25. In the case of larger-sized molecules like Acid Yellow 117, capacities were in the range of 0.23-0.42 mmol/g (untreated) and 0.29-0.40 mmol/g (acid-treated). Some tyre carbons exhibit a more superior performance than a microporous, commercial activated carbon (Calgon F400). By modelling the dye adsorption equilibrium data, the Redlich-Peterson isotherm is adopted as it has the lowest SSE. Based on the surface coverage analysis, a novel molecular orientation modelling of adsorbed dyes has been proposed and correlated with surface area and surface charge. For the acid dyes used in this study, molecules were likely to be adsorbed by the mesopore areas. Copyright 2010 Elsevier Inc. All rights reserved.

Surface Meteorology, Barrow, Alaska, Area A, B, C and D, Ongoing from 2012

DOE Data Explorer

Bob Busey; Larry Hinzman; William Cable; Vladimir Romanovsky

2014-12-04

Meteorological data are being collected at several points within four intensive study areas in Barrow. These data assist in the calculation of the energy balance at the land surface and are also useful as inputs into modeling activities.

On the influence of substrate morphology and surface area on phytofauna

USGS Publications Warehouse

Becerra-Munoz, S.; Schramm, H.L.

2007-01-01

The independent effects and interactions between substrate morphology and substrate surface area on invertebrate density or biomass colonizing artificial plant beds were assessed in a clear-water and a turbid playa lake in Castro County, Texas, USA. Total invertebrate density and biomass were consistently greater on filiform substrates than on laminar substrates with equivalent substrate surface areas. The relationship among treatments (substrates with different morphologies and surface areas) and response (invertebrate density or biomass) was assessed with equally spaced surface areas. Few statistically significant interactions between substrate morphology and surface area were detected, indicating that these factors were mostly independent from each other in their effect on colonizing invertebrates. Although infrequently, when substrate morphology and surface area were not independent, the effects of equally spaced changes in substrate surface area on the rate of change of phytofauna density or biomass per unit of substrate surface area were dependent upon substrate morphology. The absence of three-way interactions indicated that effects of substrate morphology and substrate area on phytofauna density or biomass were independent of environmental conditions outside and inside exclosures. ?? 2006 Springer Science+Business Media B.V.

Increase of porosity by combining semi-carbonization and KOH activation of formaldehyde resins to prepare high surface area carbons for supercapacitor applications

NASA Astrophysics Data System (ADS)

Heimböckel, Ruben; Kraas, Sebastian; Hoffmann, Frank; Fröba, Michael

2018-01-01

A series of porous carbon samples were prepared by combining a semi-carbonization process of acidic polymerized phenol-formaldehyde resins and a following chemical activation with KOH used in different ratios to increase specific surface area, micropore content and pore sizes of the carbons which is favourable for supercapacitor applications. Samples were characterized by nitrogen physisorption, powder X-ray diffraction, Raman spectroscopy and scanning electron microscopy. The results show that the amount of KOH, combined with the semi-carbonization step had a remarkable effect on the specific surface area (up to SBET: 3595 m2 g-1 and SDFT: 2551 m2 g-1), pore volume (0.60-2.62 cm3 g-1) and pore sizes (up to 3.5 nm). The carbons were tested as electrode materials for electrochemical double layer capacitors (EDLC) in a two electrode setup with tetraethylammonium tetrafluoroborate in acetonitrile as electrolyte. The prepared carbon material with the largest surface area, pore volume and pore sizes exhibits a high specific capacitance of 145.1 F g-1 at a current density of 1 A g-1. With a high specific energy of 31 W h kg-1 at a power density of 33028 W kg-1 and a short time relaxation constant of 0.29 s, the carbon showed high power capability as an EDLC electrode material.

Leaf Area Influence on Surface Layer in a Deciduous Forest. Part 2; Detecting Leaf Area and Surface Resistance During Transition Seasons

NASA Technical Reports Server (NTRS)

Sakai, Ricardo K.; Fitzjarrald, David R.; Moore, Kathleen E.; Sicker, John W.; Munger, Willian J.; Goulden, Michael L.; Wofsy, Steven C.

1996-01-01

Temperate deciduous forest exhibit dramatic seasonal changes in surface exchange properties following on the seasonal changes in leaf area index. The canopy resistance to water vapor transport r(sub c) decreased abruptly at leaf emergence in each year but then also continued to decrease slowly during the remaining growing season due to slowly increasing LAI. Canopy resistance and PAR-albedo (albedo from photosynthetically active radiation) began to increase about one month before leaf fall with the diminishment of CO2 gradient above the canopy as well. At this time evaporation begun to be controlled as if the canopy were leafless.

OBSERVED ASTEROID SURFACE AREA IN THE THERMAL INFRARED

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nugent, C. R.; Mainzer, A.; Masiero, J.

The rapid accumulation of thermal infrared observations and shape models of asteroids has led to increased interest in thermophysical modeling. Most of these infrared observations are unresolved. We consider what fraction of an asteroid’s surface area contributes the bulk of the emitted thermal flux for two model asteroids of different shapes over a range of thermal parameters. The resulting observed surface in the infrared is generally more fragmented than the area observed in visible wavelengths, indicating high sensitivity to shape. For objects with low values of the thermal parameter, small fractions of the surface contribute the majority of thermally emittedmore » flux. Calculating observed areas could enable the production of spatially resolved thermal inertia maps from non-resolved observations of asteroids.« less

Surface States and Effective Surface Area on Photoluminescent P-Type Porous Silicon

NASA Technical Reports Server (NTRS)

Weisz, S. Z.; Porras, A. Ramirez; Resto, O.; Goldstein, Y.; Many, A.; Savir, E.

1997-01-01

The present study is motivated by the possibility of utilizing porous silicon for spectral sensors. Pulse measurements on the porous-Si/electrolyte system are employed to determine the surface effective area and the surface-state density at various stages of the anodization process used to produce the porous material. Such measurements were combined with studies of the photoluminescence spectra. These spectra were found to shift progressively to the blue as a function of anodization time. The luminescence intensity increases initially with anodization time, reaches a maximum and then decreases with further anodization. The surface state density, on the other hand, increases with anodization time from an initial value of about 2 x 10(exp 12)/sq cm surface to about 1013 sq cm for the anodized surface. This value is attained already after -2 min anodization and upon further anodization remains fairly constant. In parallel, the effective surface area increases by a factor of 10-30. This behavior is markedly different from the one observed previously for n-type porous Si.

Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework

PubMed Central

2015-01-01

Porous graphitic carbon is essential for many applications such as energy storage devices, catalysts, and sorbents. However, current graphitic carbons are limited by low conductivity, low surface area, and ineffective pore structure. Here we report a scalable synthesis of porous graphitic carbons using a conjugated polymeric molecular framework as precursor. The multivalent cross-linker and rigid conjugated framework help to maintain micro- and mesoporous structures, while promoting graphitization during carbonization and chemical activation. The above unique design results in a class of highly graphitic carbons at temperature as low as 800 °C with record-high surface area (4073 m2 g–1), large pore volume (2.26 cm–3), and hierarchical pore architecture. Such carbons simultaneously exhibit electrical conductivity >3 times more than activated carbons, very high electrochemical activity at high mass loading, and high stability, as demonstrated by supercapacitors and lithium–sulfur batteries with excellent performance. Moreover, the synthesis can be readily tuned to make a broad range of graphitic carbons with desired structures and compositions for many applications. PMID:27162953

Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework

DOE PAGES

To, John W. F.; Chen, Zheng; Yao, Hongbin; ...

2015-05-18

Porous graphitic carbon is essential for many applications such as energy storage devices, catalysts, and sorbents. However, current graphitic carbons are limited by low conductivity, low surface area, and ineffective pore structure. Here we report a scalable synthesis of porous graphitic carbons using a conjugated polymeric molecular framework as precursor. The multivalent cross-linker and rigid conjugated framework help to maintain micro- and mesoporous structures, while promoting graphitization during carbonization and chemical activation. The above unique design results in a class of highly graphitic carbons at temperature as low as 800 °C with record-high surface area (4073 m 2 g –1),more » large pore volume (2.26 cm –3), and hierarchical pore architecture. Such carbons simultaneously exhibit electrical conductivity >3 times more than activated carbons, very high electrochemical activity at high mass loading, and high stability, as demonstrated by supercapacitors and lithium–sulfur batteries with excellent performance. Moreover, the synthesis can be readily tuned to make a broad range of graphitic carbons with desired structures and compositions for many applications.« less

Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.

2011-08-01

The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationshipmore » between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.« less

Release of ICTP and CTX telopeptides from demineralized dentin matrices: Effect of time, mass and surface area.

PubMed

Turco, Gianluca; Cadenaro, Milena; Maravić, Tatjana; Frassetto, Andrea; Marsich, Eleonora; Mazzoni, Annalisa; Di Lenarda, Roberto; Tay, Franklin R; Pashley, David H; Breschi, Lorenzo

2018-03-01

The present study evaluated the influence of time, mass and surface area of demineralized dentin collagen matrices on telopeptides release. The hypotheses tested were that the rates of ICTP and CTX release by matrix bound endogenous proteases are 1) not time-dependent, 2) unrelated to specimen mass, 3) unrelated to specimen surface area. Non-carious human molars (N=24) were collected and randomly assigned to three groups. Dentin slabs with three different thicknesses: 0.37mm, 0.75mm, and 1.50mm were completely demineralized and stored in artificial saliva for one week. Collagen degradation was evaluated by sampling storage media for ICTP and CTX telopeptidases. Activity of MMPs in the aging medium was evaluated using fluorometric activity assay kit. A statistically significant (p<0.05) decrease in the release of both ICTP and CTX fragments over time was observed irrespective of the specimen thickness. When data were normalized by the specimen mass, no significant differences were observed. Releases of ICTP and CTX were significantly related to the aging time as a function of surface area for the first 12h. Total MMP activity, mainly related to MMP-2 and -9, decreased with time (p<0.05). Because the release of collagen fragments was influenced by specimen storage time and surface area, it is likely that cleaved collagen fragments closer to the specimen surface diffuse into the incubation medium; those further away from the exposed surface are still entrapped within the demineralized dentin matrix. Bound MMPs can only degrade the substrate within the limited zone of their molecular mobility. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Measuring the surface area of fasteners

Treesearch

Douglas R. Rammer; Samuel L. Zelinka

2011-01-01

New product provides a easy way for companies to identify the surface area of threaded and nonthreaded fasteners, especially as changes in wood preservative treatments act to accelerate metal fastener corrosion in wood.

Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

PubMed

Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

2012-09-01

This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

Clay mineralogy in different geomorphic surfaces in sugarcane areas

NASA Astrophysics Data System (ADS)

Camargo, L.; Marques, J., Jr.

2012-04-01

The crystallization of the oxides and hydroxides of iron and aluminum and kaolinite of clay fraction is the result of pedogenetic processes controlled by the relief. These minerals have influence on the physical and chemical attributes of soil and exhibit spatial dependence. The pattern of spatial distribution is influenced by forms of relief as the geomorphic surfaces. In this sense, the studies aimed at understanding the relationship between relief and the distribution pattern of the clay fraction attributes contribute to the delineation of specific areas of management in the field. The objective of this study was to evaluate the spatial distribution of oxides and hydroxides of iron and aluminum and kaolinite of clay fraction and its relationship with the physical and chemical attributes in different geomorphic surfaces. Soil samples were collected in a transect each 25 m (100 samples) and in the sides of the same (200 samples) as well as an area of 500 ha (1 sample each six hectare). Geomorphic surfaces (GS) in the transect were mapped in detail to support mapping the entire area. The soil samples were taken to the laboratory for chemical, physical, and mineralogical analysis, and the pattern of spatial distribution of soil attributes was obtained by statistics and geostatistics. The GS I is considered the oldest surface of the study area, with depositional character, and a slope ranging from 0 to 4%. GS II and III are considered to be eroded, and the surface II plan a gentle slope that extends from the edge of the surface until the beginning of I and III. The crystallographic characteristics of the oxides and hydroxides of iron and aluminum and kaolinite showed spatial dependence and the distribution pattern corresponding to the limits present of the GS in the field. Surfaces I and II showed the best environments to the degree of crystallinity of hematite and the surface III to the greatest degree of crystallinity of goethite agreeing to the pedoenvironment

Human body surface area: a theoretical approach.

PubMed

Wang, Jianfeng; Hihara, Eiji

2004-04-01

Knowledge of the human body surface area has important applications in medical practice, garment design, and other engineering sizing. Therefore, it is not surprising that several expressions correlating body surface area with direct measurements of body mass and length have been reported in the literature. In the present study, based on the assumption that the exterior shape of the human body is the result of convex and concave deformations from a basic cylinder, we derive a theoretical equation minimizing body surface area (BSA) at a fixed volume (V): BSA=(9pi VL)(0.5), where L is the reference length of the body. Assuming a body density value of 1,000 kg.m(-3), the equation becomes BSA=(BM.BH/35.37)(0.5), where BSA is in square meters, BM is the body mass in kilograms, and BH is the body height in meters. BSA values calculated by means of this equation fall within +/-7% of the values obtained by means of the equations available in the literature, in the range of BSA from children to adults. It is also suggested that the above equation, which is obtained by minimizing the outer body surface at a fixed volume, implies a fundamental relation set by the geometrical constraints governing the growth and the development of the human body.

Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

NASA Astrophysics Data System (ADS)

Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

2013-01-01

The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

Nanosilver particle formation on a high surface area titanate.

PubMed

Shi, Meng; Lin, Christopher C H; Wu, Lan; Holt, Christopher M B; Mitlin, David; Kuznicki, Steven M

2010-12-01

Titanium based molecular sieves, such as ETS-10, have the ability to exchange silver ions and subsequently support self assembly of stable silver nanoparticles when heated. We report that a high surface area sodium titanate (resembling ETS-2) displays a similar ability to self template silver nanoparticles on its surface. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show high concentrations of silver nanoparticles on the surface of this sodium titanate, formed by thermal reduction of exchanged silver cations. The nanoparticles range in size from 4 to 12 nm, centered at around 6 nm. In addition to SEM and TEM, XRD and surface area analysis were used to characterize the material. The results indicate that this sodium titanate has a high surface area (>263 m2/g), and high ion exchange capacity for silver (30+ wt%) making it an excellent substrate for the exchange and generation of uniform, high-density silver nanoparticles.

Area G Perimeter Surface-Soil Sampling Environmental Surveillance for Fiscal Year 1998 Hazardous and Solid Waste Group (ESH-19)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marquis Childs

1999-09-01

Material Disposal Area G (Area G) is at Technical Area 54 at Los Alamos National Laboratory (LANL). Area G has been the principal facility for the disposal of low-level, solid-mixed, and transuranic waste since 1957. It is currently LANL's primary facility for radioactive solid waste burial and storage. As part of the annual environmental surveillance effort at Area G, surface soil samples are collected around the facility's perimeter to characterize possible radionuclide movement off the site through surface water runoff During 1998, 39 soil samples were collected and analyzed for percent moisture, tritium, plutonium-238 and 239, cesium-137 and americium-241. Tomore » assess radionuclide concentrations, the results from these samples are compared with baseline or background soil samples collected in an undisturbed area west of the active portion Area G. The 1998 results are also compared to the results from analogous samples collected during 1996 and 1997 to assess changes over this time in radionuclide activity concentrations in surface soils around the perimeter of Area G. The results indicate elevated levels of all the radionuclides assessed (except cesium-137) exist in Area G perimeter surface soils vs the baseline soils. The comparison of 1998 soil data to previous years (1996 and 1997) indicates no significant increase or decrease in radionuclide concentrations; an upward or downward trend in concentrations is not detectable at this time. These results are consistent with data comparisons done in previous years. Continued annual soil sampling will be necessary to realize a trend if one exists. The radionuclide levels found in the perimeter surface soils are above background but still considered relatively low. This perimeter surface soil data will be used for planning purposes at Area G, techniques to prevent sediment tm.nsport off-site are implemented in the areas where the highest radionuclide concentrations are indicated.« less

Volume to Surface Area Ratios of Foraminifera over the Phanerozoic

NASA Astrophysics Data System (ADS)

Cheung, K.; Gomez, D.; Guo, D.; Jost, A.; Payne, J.

2010-12-01

Although there have been numerous studies regarding the issue of the volume to surface area ratio, no study has been extensive enough to include over 35000 species of foraminifera. The Stanford Paleobiology lab undertook the enormous task of extracting from the Catalogue of Foraminifera, by Ellis and Messina, all relevant data of the foraminifera, such as the three dimensions of the organism, the magnification, and the time period in which the organism existed. For the purpose of calculating the volume and surface area, the foraminifera were generalized as ellipsoids. It is known that the surface area of foraminifera represents where the exchange between the interior body and exterior environment of the foraminifera occurs. The volume of the foraminifera indicates the physical needs of the foraminifera. With more volume in foraminifera, more body functions are occurring and more exterior resources are needed to sustain those bodily functions. Thus with a larger volume to surface area ratio, foraminifera are disadvantaged because they must use more effort in order to acquire adequate resources to fulfill their biological needs. So, the hypothesis is that when there is an increase in oxygen (a vital exterior resource of the foraminifera), the average volume to surface area ratio would be greater because the abundance of oxygen allows foraminifera to work with greater ease in maintaining an exterior resource that they cannot survive without. To prove or refute this assertion, graphs were generated in this study; the graphs indeed suggested that there is a correlation between the volume to surface area ratios and oxygen levels, illustrating that it is plausible that oxygen is a limiting factor of the volume to surface area ratio in foraminifera.

Human body surface area database and estimation formula.

PubMed

Yu, Chi-Yuang; Lin, Ching-Hua; Yang, Yi-Hsueh

2010-08-01

This study established human body surface area (BSA) database and estimation formula based on three-dimensional (3D) scanned data. For each gender, 135 subjects were drawn. The sampling was stratified in five stature heights and three body weights according to a previous survey. The 3D body surface shape was measured using an innovated 3D body scanner and a high resolution hand/foot scanner, the total body surface area (BSA) and segmental body surface area (SBSA) were computed based on the summation of every tiny triangular area of triangular meshes of the scanned surface; and the accuracy of BSA measurement is below 1%. The results of BSA and sixteen SBSAs were tabulated in fifteen strata for the Male, the Female and the Total (two genders combined). The %SBSA data was also used to revise new Lund and Browder Charts. The comparison of BSA shows that the BSA of this study is comparable with the Du Bois and Du Bois' but smaller than that of Tikuisis et al. The difference might be attributed to body size difference between the samples. The comparison of SBSA shows that the differences of SBSA between this study and the Lund and Browder Chart range between 0.00% and 2.30%. A new BSA estimation formula, BSA=71.3989 x H(.7437) x W(.4040), was obtained. An accuracy test showed that this formula has smaller estimation error than that of the Du Bois and Du Bois'; and significantly better than other BSA estimation formulae.

Estimation of the specific surface area for a porous carrier.

PubMed

Levstek, Meta; Plazl, Igor; Rouse, Joseph D

2010-03-01

In biofilm systems, treatment performance is primarily dependent upon the available biofilm growth surface area in the reactor. Specific surface area is thus a parameter that allows for making comparisons between different carrier technologies used for wastewater treatment. In this study, we estimated the effective surface area for a spherical, porous polyvinyl alcohol (PVA) gel carrier (Kuraray) that has previously demonstrated effectiveness for retention of autotrophic and heterotrophic biomass. This was accomplished by applying the GPS-X modeling tool (Hydromantis) to a comparative analysis of two moving-bed biofilm reactor (MBBR) systems. One system consisted of a lab-scale reactor that was fed synthetic wastewater under autotrophic conditions where only the nitrification process was studied. The other was a pre-denitrification pilot-scale plant that was fed real, primary-settled wastewater. Calibration of an MBBR process model for both systems indicated an effective specific surface area for PVA gel of 2500 m2/m3, versus a specific surface area of 1000 m2/m3 when only the outer surface of the gel beads is considered. In addition, the maximum specific growth rates for autotrophs and heterotrophs were estimated to be 1.2/day and 6.0/day, respectively.

Effect of degassing temperature on specific surface area and pore volume measurements of biochar

NASA Astrophysics Data System (ADS)

Sigmund, Gabriel; Hüffer, Thorsten; Kah, Melanie; Hofmann, Thilo

2017-04-01

Specific surface area, pore volume, and pore size distribution are key biochar properties that have been related to water and nutrient cycling, microbial activity as well as sorption potential for organic compounds. Specific surface area and pore volume are commonly determined by measurement of physisorption of N2 and/or CO2. The measurement requires prior degassing of the samples, which may change the structure of the materials. Information on degassing temperature is rarely reported in literature, and recommendations differ considerably between existing guidelines for biochar characterization. Therefore, the influence of degassing temperature on N2 and CO2physisorption measurements was investigated by systematically degassing a range of materials, including four biochars, Al2O3 and carbon nanotubes at different temperatures (105 ˚ C, 150 ˚ C, 200 ˚ C, 250 ˚ C and 300 ˚ C for ≥ 14 h each). Measured specific surface area and pore volume increased with increasing degassing temperature for all biochars. Additional surface area and pore volume may have become available as components in biochars volatilized during the degassing phase. The results of our study showed that (i) degassing conditions change material properties, and influence physisorption measurements for biochar (ii) comparison between parameters derived from different degassing protocols may not be appropriate, and (iii) degassing protocols should be harmonized in the biochar community [1]. [1] Sigmund, et al. (2016), "Biochar total surface area and total pore volume determined by N2 and CO2 physisorption are strongly influenced by degassing temperature", STOTEN, doi: http://dx.doi.org/10.1016/j.scitotenv.2016.12.023.

Limitations of body surface area-based activity calculation for radioembolization of hepatic metastases in colorectal cancer.

PubMed

Lam, Marnix G E H; Louie, John D; Abdelmaksoud, Mohamed H K; Fisher, George A; Cho-Phan, Cheryl D; Sze, Daniel Y

2014-07-01

To calculate absorbed radiation doses in patients treated with resin microspheres prescribed by the body surface area (BSA) method and to analyze dose-response and toxicity relationships. A retrospective review was performed of 45 patients with colorectal carcinoma metastases who received single-session whole-liver resin microsphere radioembolization. Prescribed treatment activity was calculated using the BSA method. Liver volumes and whole-liver absorbed doses (D(WL)) were calculated. D(WL) was correlated with toxicity and radiographic and biochemical response. The standard BSA-based administered activity (range, 0.85-2.58 GBq) did not correlate with D(WL) (mean, 50.4 Gy; range, 29.8-74.7 Gy; r = -0.037; P = .809) because liver weight was highly variable (mean, 1.89 kg; range, 0.94-3.42 kg) and strongly correlated with D(WL) (r = -0.724; P < .001) but was not accounted for in the BSA method. Patients with larger livers were relatively underdosed, and patients with smaller livers were relatively overdosed. Patients who received D(WL) > 50 Gy experienced more toxicity and adverse events (> grade 2 liver toxicity, 46% vs 17%; P < .05) but also responded better to the treatment than patients who received D(WL)< 50 Gy (disease control, 88% vs 24%; P < .01). Using the standard BSA formula, the administered activity did not correlate with D(WL). Based on this short-term follow-up after salvage therapy in patients with late stage metastatic colorectal carcinoma, dose-response and dose-toxicity relationships support using a protocol based on liver volume rather than BSA to prescribe the administered activity. Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.

Color Shaded-Relief and Surface-Classification Maps of the Fish Creek Area, Harrison Bay Quadrangle, Northern Alaska

USGS Publications Warehouse

Mars, John L.; Garrity, Christopher P.; Houseknecht, David W.; Amoroso, Lee; Meares, Donald C.

2007-01-01

Introduction The northeastern part of the National Petroleum Reserve in Alaska (NPRA) has become an area of active petroleum exploration during the past five years. Recent leasing and exploration drilling in the NPRA requires the U.S. Bureau of Land Management (BLM) to manage and monitor a variety of surface activities that include seismic surveying, exploration drilling, oil-field development drilling, construction of oil-production facilities, and construction of pipelines and access roads. BLM evaluates a variety of permit applications, environmental impact studies, and other documents that require rapid compilation and analysis of data pertaining to surface and subsurface geology, hydrology, and biology. In addition, BLM must monitor these activities and assess their impacts on the natural environment. Timely and accurate completion of these land-management tasks requires elevation, hydrologic, geologic, petroleum-activity, and cadastral data, all integrated in digital formats at a higher resolution than is currently available in nondigital (paper) formats. To support these land-management tasks, a series of maps was generated from remotely sensed data in an area of high petroleum-industry activity (fig. 1). The maps cover an area from approximately latitude 70?00' N. to 70?30' N. and from longitude 151?00' W. to 153?10' W. The area includes the Alpine oil field in the east, the Husky Inigok exploration well (site of a landing strip) in the west, many of the exploration wells drilled in NPRA since 2000, and the route of a proposed pipeline to carry oil from discovery wells in NPRA to the Alpine oil field. This map area is referred to as the 'Fish Creek area' after a creek that flows through the region. The map series includes (1) a color shaded-relief map based on 5-m-resolution data (sheet 1), (2) a surface-classification map based on 30-m-resolution data (sheet 2), and (3) a 5-m-resolution shaded relief-surface classification map that combines the shaded

Quaternary Geology and Surface Faulting Hazard: Active and Capable Faults in Central Apennines, Italy

NASA Astrophysics Data System (ADS)

Falcucci, E.; Gori, S.

2015-12-01

The 2009 L'Aquila earthquake (Mw 6.1), in central Italy, raised the issue of surface faulting hazard in Italy, since large urban areas were affected by surface displacement along the causative structure, the Paganica fault. Since then, guidelines for microzonation were drew up that take into consideration the problem of surface faulting in Italy, and laying the bases for future regulations about related hazard, similarly to other countries (e.g. USA). More specific guidelines on the management of areas affected by active and capable faults (i.e. able to produce surface faulting) are going to be released by National Department of Civil Protection; these would define zonation of areas affected by active and capable faults, with prescriptions for land use planning. As such, the guidelines arise the problem of the time interval and general operational criteria to asses fault capability for the Italian territory. As for the chronology, the review of the international literature and regulatory allowed Galadini et al. (2012) to propose different time intervals depending on the ongoing tectonic regime - compressive or extensional - which encompass the Quaternary. As for the operational criteria, the detailed analysis of the large amount of works dealing with active faulting in Italy shows that investigations exclusively based on surface morphological features (e.g. fault planes exposition) or on indirect investigations (geophysical data), are not sufficient or even unreliable to define the presence of an active and capable fault; instead, more accurate geological information on the Quaternary space-time evolution of the areas affected by such tectonic structures is needed. A test area for which active and capable faults can be first mapped based on such a classical but still effective methodological approach can be the central Apennines. Reference Galadini F., Falcucci E., Galli P., Giaccio B., Gori S., Messina P., Moro M., Saroli M., Scardia G., Sposato A. (2012). Time

Principal curvatures and area ratio of propagating surfaces in isotropic turbulence

NASA Astrophysics Data System (ADS)

Zheng, Tianhang; You, Jiaping; Yang, Yue

2017-10-01

We study the statistics of principal curvatures and the surface area ratio of propagating surfaces with a constant or nonconstant propagating velocity in isotropic turbulence using direct numerical simulation. Propagating surface elements initially constitute a plane to model a planar premixed flame front. When the statistics of evolving propagating surfaces reach the stationary stage, the statistical profiles of principal curvatures scaled by the Kolmogorov length scale versus the constant displacement speed scaled by the Kolmogorov velocity scale collapse at different Reynolds numbers. The magnitude of averaged principal curvatures and the number of surviving surface elements without cusp formation decrease with increasing displacement speed. In addition, the effect of surface stretch on the nonconstant displacement speed inhibits the cusp formation on surface elements at negative Markstein numbers. In order to characterize the wrinkling process of the global propagating surface, we develop a model to demonstrate that the increase of the surface area ratio is primarily due to positive Lagrangian time integrations of the area-weighted averaged tangential strain-rate term and propagation-curvature term. The difference between the negative averaged mean curvature and the positive area-weighted averaged mean curvature characterizes the cellular geometry of the global propagating surface.

Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

PubMed

Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

2013-11-01

Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

Surface-Activated Coupling Reactions Confined on a Surface.

PubMed

Dong, Lei; Liu, Pei Nian; Lin, Nian

2015-10-20

Chemical reactions may take place in a pure phase of gas or liquid or at the interface of two phases (gas-solid or liquid-solid). Recently, the emerging field of "surface-confined coupling reactions" has attracted intensive attention. In this process, reactants, intermediates, and products of a coupling reaction are adsorbed on a solid-vacuum or a solid-liquid interface. The solid surface restricts all reaction steps on the interface, in other words, the reaction takes place within a lower-dimensional, for example, two-dimensional, space. Surface atoms that are fixed in the surface and adatoms that move on the surface often activate the surface-confined coupling reactions. The synergy of surface morphology and activity allow some reactions that are inefficient or prohibited in the gas or liquid phase to proceed efficiently when the reactions are confined on a surface. Over the past decade, dozens of well-known "textbook" coupling reactions have been shown to proceed as surface-confined coupling reactions. In most cases, the surface-confined coupling reactions were discovered by trial and error, and the reaction pathways are largely unknown. It is thus highly desirable to unravel the mechanisms, mechanisms of surface activation in particular, of the surface-confined coupling reactions. Because the reactions take place on surfaces, advanced surface science techniques can be applied to study the surface-confined coupling reactions. Among them, scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) are the two most extensively used experimental tools. The former resolves submolecular structures of individual reactants, intermediates, and products in real space, while the latter monitors the chemical states during the reactions in real time. Combination of the two methods provides unprecedented spatial and temporal information on the reaction pathways. The experimental findings are complemented by theoretical modeling. In particular, density

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts

NASA Technical Reports Server (NTRS)

Bhatt, R. T.; Palczer, A. R.

1998-01-01

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

Determining Surface Roughness in Urban Areas Using Lidar Data

NASA Technical Reports Server (NTRS)

Holland, Donald

2009-01-01

An automated procedure has been developed to derive relevant factors, which can increase the ability to produce objective, repeatable methods for determining aerodynamic surface roughness. Aerodynamic surface roughness is used for many applications, like atmospheric dispersive models and wind-damage models. For this technique, existing lidar data was used that was originally collected for terrain analysis, and demonstrated that surface roughness values can be automatically derived, and then subsequently utilized in disaster-management and homeland security models. The developed lidar-processing algorithm effectively distinguishes buildings from trees and characterizes their size, density, orientation, and spacing (see figure); all of these variables are parameters that are required to calculate the estimated surface roughness for a specified area. By using this algorithm, aerodynamic surface roughness values in urban areas can then be extracted automatically. The user can also adjust the algorithm for local conditions and lidar characteristics, like summer/winter vegetation and dense/sparse lidar point spacing. Additionally, the user can also survey variations in surface roughness that occurs due to wind direction; for example, during a hurricane, when wind direction can change dramatically, this variable can be extremely significant. In its current state, the algorithm calculates an estimated surface roughness for a square kilometer area; techniques using the lidar data to calculate the surface roughness for a point, whereby only roughness elements that are upstream from the point of interest are used and the wind direction is a vital concern, are being investigated. This technological advancement will improve the reliability and accuracy of models that use and incorporate surface roughness.

Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Sun, Fei; Gao, Jihui; Liu, Xin; Pi, Xinxin; Yang, Yuqi; Wu, Shaohua

2016-11-01

Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m2 g-1) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g-1 at 0.5 A g-1 and still 120 F g-1 at a high rate of 30 A g-1. There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg-1 and 4.03 Wh kg-1 with the corresponding power densities of 108 W kg-1 and 6.49 kW kg-1, respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.

Surface Soil Preparetion for Leguminous Plants Growing in Degraded Areas by Mining Located in Amazon Forest-Brazil

NASA Astrophysics Data System (ADS)

Irio Ribeiro, Admilson; Hashimoto Fengler, Felipe; Araújo de Medeiros, Gerson; Márcia Longo, Regina; Frederici de Mello, Giovanna; José de Melo, Wanderley

2015-04-01

The revegetation of areas degraded by mining usually requires adequate mobilization of surface soil for the development of the species to be implemented. Unlike the traditional tillage, which has periodicity, the mobilization of degraded areas for revegetation can only occur at the beginning of the recovery stage. In this sense, the process of revegetation has as purpose the establishment of local native vegetation with least possible use of inputs and superficial tillage in order to catalyze the process of natural ecological succession, promoting the reintegration of areas and minimizing the negative impacts of mining activities in environmental. In this context, this work describes part of a study of land reclamation by tin exploitation in the Amazon ecosystem in the National Forest Jamari- Rondonia Brazil. So, studied the influence of surface soil mobilization in pit mine areas and tailings a view to the implementation of legumes. The results show that the surface has areas of mobilizing a significant effect on the growth of leguminous plants, areas for both mining and to tailings and pit mine areas.

Supercritical processing as a route to high internal surface areas and permanent microporosity in metal-organic framework materials.

PubMed

Nelson, Andrew P; Farha, Omar K; Mulfort, Karen L; Hupp, Joseph T

2009-01-21

Careful processing of four representative metal-organic framework (MOF) materials with liquid and supercritical carbon dioxide (ScD) leads to substantial, or in some cases spectacular (up to 1200%), increases in gas-accessible surface area. Maximization of surface area is key to the optimization of MOFs for many potential applications. Preliminary evidence points to inhibition of mesopore collapse, and therefore micropore accessibility, as the basis for the extraordinarily efficacious outcome of ScD-based activation.

Surface active gold nanoparticles biosynthesis by new approach for bionanocatalytic activity.

PubMed

Vasantharaj, S; Sripriya, N; Shanmugavel, M; Manikandan, E; Gnanamani, A; Senthilkumar, P

2018-02-01

In the present day, nanotechnology is one of the most promising leading scientific and potentials areas in modern key technology development toward to the humankind. The synthesis of noble metal nanoparticles (NPs) is an expanding research area due to the possible applications for the development of bio-medical applications. Eco-friendly approach for the biosynthesis of gold nanoparticles (AuNPs) using the aqueous extract from Ruellia tuberosa and Phyllanthus acidus (leaf and twig) for the first time. Surface active AuNPs were characterized by UV-Vis spectroscopy, FTIR (Fourier transform infrared) spectroscopy, DSC (differential scanning colorimetry), DLS (dynamic light scattering) and environmental SEM (scanning electron microscope) analysis at room temperature (RT). Enhanced surface plasmon resonance (SPR) absorbance UV visible optical spectra were detected in the range of 552, 548, 558 and 536 nm. SEM and DLS (transmission mode) analysis confirmed the morphology of the nanoparticles to be spherical with the average size in the range of 88.37, 94.31, 82.23 and 81.36 nm. Further they have enhanced the enzyme activity on α-amylase, cellulase, and xylanase. The results suggest that the phyto-fabricated AuNPs from R. tuberosa and P. acidus is simple, less expensive, eco-friendly, green synthesis and also can be exploited for the potential future industrial and bio-medical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Self-Formed Channel Devices Based on Vertically Grown 2D Materials with Large-Surface-Area and Their Potential for Chemical Sensor Applications.

PubMed

Kim, Chaeeun; Park, Jun-Cheol; Choi, Sun Young; Kim, Yonghun; Seo, Seung-Young; Park, Tae-Eon; Kwon, Se-Hun; Cho, Byungjin; Ahn, Ji-Hoon

2018-04-01

2D layered materials with sensitive surfaces are promising materials for use in chemical sensing devices, owing to their extremely large surface-to-volume ratios. However, most chemical sensors based on 2D materials are used in the form of laterally defined active channels, in which the active area is limited to the actual device dimensions. Therefore, a novel approach for fabricating self-formed active-channel devices is proposed based on 2D semiconductor materials with very large surface areas, and their potential gas sensing ability is examined. First, the vertical growth phenomenon of SnS 2 nanocrystals is investigated with large surface area via metal-assisted growth using prepatterned metal electrodes, and then self-formed active-channel devices are suggested without additional pattering through the selective synthesis of SnS 2 nanosheets on prepatterned metal electrodes. The self-formed active-channel device exhibits extremely high response values (>2000% at 10 ppm) for NO 2 along with excellent NO 2 selectivity. Moreover, the NO 2 gas response of the gas sensing device with vertically self-formed SnS 2 nanosheets is more than two orders of magnitude higher than that of a similar exfoliated SnS 2 -based device. These results indicate that the facile device fabrication method would be applicable to various systems in which surface area plays an important role. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Can foot anthropometric measurements predict dynamic plantar surface contact area?

PubMed

McPoil, Thomas G; Vicenzino, Bill; Cornwall, Mark W; Collins, Natalie

2009-10-28

Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 +/- 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R2 = 0.76, p < 0.0001). The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

Can foot anthropometric measurements predict dynamic plantar surface contact area?

PubMed Central

2009-01-01

Background Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Methods Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 ± 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. Results A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R2 = 0.76, p < 0.0001). Conclusion The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region. PMID:19863799

Geothermic analysis of high temperature hydrothermal activities area in Western plateau of Sichuan province, China

NASA Astrophysics Data System (ADS)

Zhang, J.

2016-12-01

There is a high temperature hydrothermal activity area in the western plateau of Sichuan. More than 200 hot springs points have been found in the region, including 11 hot spring water temperature above local boiling point. Most of these distribute along Jinshajjiang fracture, Dege-Xiangcheng fracture, Ganzi-Litang fracture as well as Xianshuihe fracture, and form three high-temperature hydrothermal activity strips in the NW-SE direction. Using gravity, magnetic, seismic and helium isotope data, this paper analyzed the crust-mantle heat flow structure, crustal heat source distribution and water heating system. The results show that the geothermal activity mainly controlled by the "hot" crust. The ratio of crustal heat flow and surface heat flow is higher than 60%. In the high temperature hydrothermal activities area, there is lower S wave velocity zone with Vs<3.2 km/s in 15 30 km depth in middle and lower crust. Basing on the S wave velocity inversion temperature of crust-mantle, it has been found that there is a high temperature layer with 850 1000 ° in 20 40 km depth. It is the main heat source of high temperature hydrothermal activity area of western Sichuan. Our argument is that atmospheric precipitation, surface water infiltrated along the fault fracture into the crustal deep, heating by crustal hot source, and circulation to surface become high temperature hot water. Geothermal water mainly reserve in the Triassic strata of the containing water good carbonate rocks, and in the intrusive granite which is along the fault zone. The thermal energy of Surface heat thermal activities mainly comes from the high-temperature hot source which is located in the middle and lower crust. Being in the deep crustal fracture, the groundwater infiltrated to the deep crust and absorbed heat, then, quickly got back to the surface and formed high hot springs.

Estimation of the reactive mineral surface area during CO2-rich fluid-rock interaction: the influence of neogenic phases

NASA Astrophysics Data System (ADS)

Scislewski, A.; Zuddas, P.

2010-12-01

Mineral dissolution and precipitation reactions actively participate to control fluid chemistry during water-rock interaction. It is however, difficult to estimate and well normalize bulk reaction rates if the mineral surface area exposed to the aqueous solution and effectively participating on the reactions is unknown. We evaluated the changing of the reactive mineral surface area during the interaction between CO2-rich fluids and Albitite/Granitoid rocks (similar mineralogy but different abundances), reacting under flow-through conditions. Our methodology, adopting an inverse modeling approach, is based on the estimation of dissolution rate and reactive surface area of the different minerals participating in the reactions by the reconstruction the chemical evolution of the interacting fluids. The irreversible mass-transfer processes is defined by a fractional degree of advancement, while calculations were carried out for Albite, Microcline, Biotite and Calcite assuming that the ion activity of dissolved silica and aluminium ions was limited by the equilibrium with quartz and kaolinite. Irrespective of the mineral abundance in granite and albitite, we found that mineral dissolution rates did not change significantly in the investigated range of time where output solution’s pH remained in the range between 6 and 8, indicating that the observed variation in fluid composition depends not on pH but rather on the variation of the parent mineral’s reactive surface area. We found that the reactive surface area of Albite varied by more than 2 orders of magnitude, while Microcline, Calcite and Biotite surface areas changed by 1-2 orders of magnitude. We propose that parent mineral chemical heterogeneity and, particularly, the stability of secondary mineral phases may explain the observed variation of the reactive surface area of the minerals. Formation of coatings at the dissolving parent mineral surfaces significantly reduced the amount of surface available to react

Why Do We Need the Derivative for the Surface Area?

ERIC Educational Resources Information Center

Hristova, Yulia; Zeytuncu, Yunus E.

2016-01-01

Surface area and volume computations are the most common applications of integration in calculus books. When computing the surface area of a solid of revolution, students are usually told to use the frustum method instead of the disc method; however, a rigorous explanation is rarely provided. In this note, we provide one by using geometric…

Anti-inflammatory and anti-bacterial activity, and cytotoxicity of halloysite surfaces.

PubMed

Cervini-Silva, Javiera; Nieto-Camacho, Antonio; Palacios, Eduardo; Montoya, José Ascención; Gómez-Vidales, Virginia; Ramírez-Apán, María Teresa

2013-11-01

Halloysite is a naturally-occurring nanomaterial occurring in the thousands of tons and that serves as biomaterial, with applications in the areas of biotechnology, pharmaceutical, and medical research. This study reports on the anti-inflammatory, cytotoxic, and anti-oxidant activity of halloysite Jarrahdale (collected at ∼ 45 km SE of Perth, Western Australia; JA), Dragon Mine (provided by Natural Nano Inc., Rochester, New York; NA), and Kalgoorie Archean (collected at Siberia, ∼ 85km NW of Kalgoorlie, West Australia; PA). Prior to biological testing, halloysites were characterized by 27Al and 29Si Nuclear Magnetic Resonance Spectroscopy, the anti-inflammatory activity was determined by (a) the mouse ear edema method, using 12-o-tetradecanoylphorbol-13-acetate (TPA) as anti-inflammatory agent; and (b) the myeloperoxidase enzymatic activity method (MPO). Cell viability was determined using the MTT method. Sample characterization by NMR method showed similar symmetry and atomic environments, with no evidence of distortion(s) due to shiftings in atomic ordering or electron density. The anti-inflammatory activity followed the order: PA>JA>NA, and remained invariant with time. Prolonged anti-inflammatory activity related inversely to surface area and lumen space. The low extent of infiltration at shorter reaction times confirmed a limiting number of active surface sites. EPR intensity signals followed the order: JA>NA>PA. The poor stabilization of RO species in PA suspensions was explained by tube alignment provoking occlusion, thus limiting transfer of H(+) or e(-) from-and-to the surface, and decreases in acidity associated to Al(oct). Cell viability (%) varied from one surface to the other, PA(92.3 ± 6.0), JA(84.9 ± 7.8), and NA(78.0 ± 5.6), but related directly to SBET values. Copyright © 2013 Elsevier B.V. All rights reserved.

Specific surface area of a crushed welded tuff before and after aqueous dissolution

USGS Publications Warehouse

Reddy, M.M.; Claassen, H.C.

1994-01-01

Specific surface areas were measured for several reference minerals (anorthoclase, labradorite and augite), welded tuff and stream sediments from Snowshoe Mountain, near Creede, Colorado. Crushed and sieved tuff had an unexpectedly small variation in specific surface area over a range of size fractions. Replicate surface area measurements of the largest and smallest tuff particle size fractions examined (1-0.3 mm and <0.212 mm) were 2.3 ?? 0.2 m2/g for each size fraction. Reference minerals prepared in the same way as the tuff had smaller specific surface areas than that of the tuff of the same size fraction. Higher than expected tuff specific surface areas appear to be due to porous matrix. Tuff, reacted in solutions with pH values from 2 to 6, had little change in specific surface area in comparison with unreacted tuff. Tuff, reacted with solutions having high acid concentrations (0.1 M hydrochloric acid or sulfuric-hydrofluoric acid), exhibited a marked increase in specific surface area compared to unreacted tuff. ?? 1994.

High surface area TiO2/SBA-15 nanocomposites: Synthesis, microstructure and adsorption-enhanced photocatalysis

NASA Astrophysics Data System (ADS)

Wei, J. Q.; Chen, X. J.; Wang, P. F.; Han, Y. B.; Xu, J. C.; Hong, B.; Jin, H. X.; Jin, D. F.; Peng, X. L.; Li, J.; Yang, Y. T.; Ge, H. L.; Wang, X. Q.

2018-06-01

Mesoporous SBA-15 was used to anchor TiO2 nanoparticles into the mesopores to form high surface area TiO2/SBA-15 nanocomposites, and then the influence of mesoporous-structure on the photocatalytic performance was investigated. TiO2/SBA-15 nanocomposites possessed the high specific surface area and appropriate pore size, indicating the excellent adsorption performance. TiO2/SBA-15 nanocomposites exhibited the higher photocatalytic activity to degrade dyes (methylene blue: MB) than TiO2 (removing SBA-15), which should attributed to the excellent adsorption performance of the nanocomposites. MB was absorbed to form the higher concentration near TiO2/SBA-15 photocatalysts, and the photocatalytic degradation for MB was improved.

A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

2016-10-01

In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

Rippled area formed by surface plasmon polaritons upon femtosecond laser double-pulse irradiation of silicon.

PubMed

Derrien, Thibault J-Y; Krüger, Jörg; Itina, Tatiana E; Höhm, Sandra; Rosenfeld, Arkadi; Bonse, Jörn

2013-12-02

The formation of near-wavelength laser-induced periodic surface structures (LIPSS) on silicon upon irradiation with sequences of Ti:sapphire femtosecond laser pulse pairs (pulse duration 150 fs, central wavelength 800 nm) is studied theoretically. For this purpose, the nonlinear generation of conduction band electrons in silicon and their relaxation is numerically calculated using a two-temperature model approach including intrapulse changes of optical properties, transport, diffusion and recombination effects. Following the idea that surface plasmon polaritons (SPP) can be excited when the material turns from semiconducting to metallic state, the "SPP active area" is calculated as function of fluence and double-pulse delay up to several picoseconds and compared to the experimentally observed rippled surface areas. Evidence is presented that multi-photon absorption explains the large increase of the rippled area for temporally overlapping pulses. For longer double-pulse delays, relevant relaxation processes are identified. The results demonstrate that femtosecond LIPSS on silicon are caused by the excitation of SPP and can be controlled by temporal pulse shaping.

Facile synthesis of efficient visible active C-doped TiO{sub 2} nanomaterials with high surface area for the simultaneous removal of phenol and Cr(VI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mani, A.Daya; Reddy, P.Manoj Kumar; Srinivaas, M.

2015-01-15

Highlights: • Facile synthesis of C-doped TiO{sub 2} nanomaterials with high surface area. • Utilization of citric acid and ascorbic acid as fuels based on evolution of gases. • Enhanced visible activity for the oxidation of phenol and reduction of Cr(VI). • Study of simultaneous oxidation of phenol and reduction of Cr(VI) for the first time. • Proposed plausible mechanism for the simultaneous removal of phenol and Cr(VI). - Abstract: A single step synthesis of carbon doped TiO{sub 2} (anatase) nanomaterials have been reported by using combustion synthesis using ascorbic acid and citric acid fuels. X-ray diffraction studies indicated themore » formation of nanosized anatase titania, whereas, transmission electron microscopy confirmed the formation of nanosized TiO{sub 2} anatase. The carbon doping into TiO{sub 2} matrix was identified by X-ray photoelectron spectroscopy, whereas, thermogravimetric study quantified the carbon doping. Diffuse reflectance UV–vis spectra indicated the band gap of less than 3 eV, a prerequisite for the photocatalytic activity under visible light irradiation. The N{sub 2} adsorption studies revealed the high surface area (upto 290 m{sup 2}/g) of the synthesized photocatalysts. Typical photocatalytic activity data indicated that the simultaneous removal of Cr(VI) and phenol is advantageous than degradation of the individual pollutants.« less

A Comparative Study of Molecular Structure, pKa, Lipophilicity, Solubility, Absorption and Polar Surface Area of Some Antiplatelet Drugs.

PubMed

Remko, Milan; Remková, Anna; Broer, Ria

2016-03-19

Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor) and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p) level of density functional theory. Computed dissociation constants show that the active metabolites of prodrugs (ticlopidine, clopidogrel and prasugrel) and drugs elinogrel and cangrelor are completely ionized at pH 7.4. Both ticagrelor and its active metabolite are present at pH = 7.4 in neutral undissociated form. The thienopyridine prodrugs ticlopidine, clopidogrel and prasugrel are lipophilic and insoluble in water. Their lipophilicity is very high (about 2.5-3.5 logP values). The polar surface area, with regard to the structurally-heterogeneous character of these antiplatelet drugs, is from very large interval of values of 3-255 Ų. Thienopyridine prodrugs, like ticlopidine, clopidogrel and prasugrel, with the lowest polar surface area (PSA) values, exhibit the largest absorption. A high value of polar surface area (PSA) of cangrelor (255 Ų) results in substantial worsening of the absorption in comparison with thienopyridine drugs.

High surface area bio-waste based carbon as a superior electrode for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Maharjan, Makhan; Bhattarai, Arjun; Ulaganathan, Mani; Wai, Nyunt; Oo, Moe Ohnmar; Wang, Jing-Yuan; Lim, Tuti Mariana

2017-09-01

Activated carbon (AC) with high surface area (1901 m2 g-1) is synthesized from low cost bio-waste orange (Citrus sinensis) peel for vanadium redox flow battery (VRB). The composition, structure and electrochemical properties of orange peel derived AC (OP-AC) are characterized by elemental analyzer, field emission-scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy. CV results show that OP-AC coated bipolar plate demonstrates improved electro-catalytic activity in both positive and negative side redox couples than the pristine bipolar plate electrode and this is ascribed to the high surface area of OP-AC which provides effective electrode area and better contact between the porous electrode and bipolar plate. Consequently, the performance of VRB in a static cell shows higher energy efficiency for OP-AC electrode than the pristine electrode at all current densities tested. The results suggest the OP-AC to be a promising electrode for VRB applications and can be incorporated into making conducting plastics electrode to lower the VRB cell stack weight and cost.

The fraction of total hand surface area involved in young children's outdoor hand-to-object contacts.

PubMed

AuYeung, Willa; Canales, Robert A; Leckie, James O

2008-11-01

Information on the fraction of total hand surface area touching a contaminated object is necessary in accurately estimating contaminant (e.g., pesticides, pathogens) loadings onto the hands during hand-to-object contacts. While several existing physical-stochastic human exposure models require such surface area data to estimate dermal and non-dietary ingestion exposure, there are very limited data sets. This paper provides statistical distributions of fractional surface areas (FSAs) for children's outdoor hand contacts. These distributions were constructed by combining information collected from two distinct studies exploring children's activity patterns and quantifying hand contact surface area. Results show that for outdoor contacts with "All Objects", a range of 0.13-0.27 captured median FSAs, while a range of 0.12-0.24 captured time-weighted FSAs. Overall, an FSA of 0.31 captured 80-100% of FSAs involved in each child's outdoor hand contacts, depending upon the object of interest. These values are much lower than the often conservative assumptions of up to 1 (i.e., the entire hand) that researchers currently make regarding FSAs involved in indoor and outdoor contacts [USEPA, 1997. Standard operating procedures (SOPs) for residential exposure assessments. Contract no. 68-W6-0030. http://www.epa.gov/pesticides/trac/science/trac6a05.pdf].

Enhancement of surface area and wettability properties of boron doped diamond by femtosecond laser-induced periodic surface structuring

DOE PAGES

Granados, Eduardo; Calderon, Miguel Martinez; Krzywinski, Jacek; ...

2017-08-28

We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in boron-doped diamond (BDD) by irradiation with femtosecond near-IR laser pulses. The results show that the obtained LIPSS are perpendicular to the laser polarization, and the ripple periodicity is on the order of half of the irradiation wavelength. The surface structures and their electrochemical properties were characterized using Raman micro-spectroscopy, in combination with scanning electron and atomic force microscopies. The textured BDD surface showed a dense and large surface area with no change in its structural characteristics. The effective surface area of the textured BDD electrode was approximately 50% largermore » than that of a planar substrate, while wetting tests showed that the irradiated area becomes highly hydrophilic. Lastly, our results indicate that LIPSS texturing of BDD is a straightforward and simple technique for enhancing the surface area and wettability properties of the BDD electrodes, which could enable higher current efficiency and lower energy consumption in the electrochemical oxidation of toxic organics.« less

Enhancement of surface area and wettability properties of boron doped diamond by femtosecond laser-induced periodic surface structuring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Granados, Eduardo; Calderon, Miguel Martinez; Krzywinski, Jacek

We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in boron-doped diamond (BDD) by irradiation with femtosecond near-IR laser pulses. The results show that the obtained LIPSS are perpendicular to the laser polarization, and the ripple periodicity is on the order of half of the irradiation wavelength. The surface structures and their electrochemical properties were characterized using Raman micro-spectroscopy, in combination with scanning electron and atomic force microscopies. The textured BDD surface showed a dense and large surface area with no change in its structural characteristics. The effective surface area of the textured BDD electrode was approximately 50% largermore » than that of a planar substrate, while wetting tests showed that the irradiated area becomes highly hydrophilic. Lastly, our results indicate that LIPSS texturing of BDD is a straightforward and simple technique for enhancing the surface area and wettability properties of the BDD electrodes, which could enable higher current efficiency and lower energy consumption in the electrochemical oxidation of toxic organics.« less

Spatial variability of specific surface area of arable soils in Poland

NASA Astrophysics Data System (ADS)

Sokolowski, S.; Sokolowska, Z.; Usowicz, B.

2012-04-01

Evaluation of soil spatial variability is an important issue in agrophysics and in environmental research. Knowledge of spatial variability of physico-chemical properties enables a better understanding of several processes that take place in soils. In particular, it is well known that mineralogical, organic, as well as particle-size compositions of soils vary in a wide range. Specific surface area of soils is one of the most significant characteristics of soils. It can be not only related to the type of soil, mainly to the content of clay, but also largely determines several physical and chemical properties of soils and is often used as a controlling factor in numerous biological processes. Knowledge of the specific surface area is necessary in calculating certain basic soil characteristics, such as the dielectric permeability of soil, water retention curve, water transport in the soil, cation exchange capacity and pesticide adsorption. The aim of the present study is two-fold. First, we carry out recognition of soil total specific surface area patterns in the territory of Poland and perform the investigation of features of its spatial variability. Next, semivariograms and fractal analysis are used to characterize and compare the spatial variability of soil specific surface area in two soil horizons (A and B). Specific surface area of about 1000 samples was determined by analyzing water vapor adsorption isotherms via the BET method. The collected data of the values of specific surface area of mineral soil representatives for the territory of Poland were then used to describe its spatial variability by employing geostatistical techniques and fractal theory. Using the data calculated for some selected points within the entire territory and along selected directions, the values of semivariance were determined. The slope of the regression line of the log-log plot of semi-variance versus the distance was used to estimate the fractal dimension, D. Specific surface area

Effect of solution and leaf surface polarity on droplet spread area and contact angle.

PubMed

Nairn, Justin J; Forster, W Alison; van Leeuwen, Rebecca M

2016-03-01

How much an agrochemical spray droplet spreads on a leaf surface can significantly influence efficacy. This study investigates the effect solution polarity has on droplet spreading on leaf surfaces and whether the relative leaf surface polarity, as quantified using the wetting tension dielectric (WTD) technique, influences the final spread area. Contact angles and spread areas were measured using four probe solutions on 17 species. Probe solution polarity was found to affect the measured spread area and the contact angle of the droplets on non-hairy leaves. Leaf hairs skewed the spread area measurement, preventing investigation of the influence of surface polarity on hairy leaves. WTD-measured leaf surface polarity of non-hairy leaves was found to correlate strongly with the effect of solution polarity on spread area. For non-polar leaf surfaces the spread area decreases with increasing solution polarity, for neutral surfaces polarity has no effect on spread area and for polar leaf surfaces the spread area increases with increasing solution polarity. These results attest to the use of the WTD technique as a means to quantify leaf surface polarity. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Robot Towed Shortwave Infrared Camera for Specific Surface Area Retrieval of Surface Snow

NASA Astrophysics Data System (ADS)

Elliott, J.; Lines, A.; Ray, L.; Albert, M. R.

2017-12-01

Optical grain size and specific surface area are key parameters for measuring the atmospheric interactions of snow, as well as tracking metamorphosis and allowing for the ground truthing of remote sensing data. We describe a device using a shortwave infrared camera with changeable optical bandpass filters (centered at 1300 nm and 1550 nm) that can be used to quickly measure the average SSA over an area of 0.25 m^2. The device and method are compared with calculations made from measurements taken with a field spectral radiometer. The instrument is designed to be towed by a small autonomous ground vehicle, and therefore rides above the snow surface on ultra high molecular weight polyethylene (UHMW) skis.

Nano- to Formation-Scale Estimates of Mineral-Specific Reactive Surface Area

NASA Astrophysics Data System (ADS)

Cole, D. R.; Swift, A.; Sheets, J.; Anovitz, L. M.

2017-12-01

Predictions of changes in fluid composition, coupled with the evolution of the solid matrix, include the generation and testing of reactive transport models. However, translating a heterogeneous natural system into physical and chemical model parameters, including the critical but poorly-constrained metric of fluid-accessible surface area, continues to challenge Earth scientists. Studies of carbon storage capacity, permeability, rock strain due to mineral dissolution and precipitation, or the prediction of rock evolution through diagenesis and weathering each consider macroscale outcomes of processes that often are critically impacted by rock surface geometry at the nanoscale. The approach taken here is to consider the whole vertical extent of a saline reservoir and then to address two questions. First, what is the accessible surface area for each major mineral, and for all adjacent pore sizes from <2 nm on up, within each major lithofacies in that formation? Second, with the formation thus divided into units of analysis, parameterized, and placed into geologic context, what constraints can be placed on reactive surface area as a function of mineral composition? A complex sandstone covering a substantial fraction of the quartz-K-feldspar-illite ternary is selected and mineral-specific surface area quantified using neutron scattering, nitrogen and mercury porosimetry, multi-signal high-resolution mineral mapping, and other techniques. For neutron scattering, scale-specific pore geometries enable more accurate translation of volume into surface area. By applying this workflow to all end-member lithologies of this reservoir formation, equations and maps of surface area as a function of position on a quartz-feldspar-clay ternary plot are developed for each major mineral. Results from this work therefore advance our ability to parameterize models not just for the particular formation studied, but for similar geologic units as well.

Determining surface areas of marine alga cells by acid-base titration method.

PubMed

Wang, X; Ma, Y; Su, Y

1997-09-01

A new method for determining the surface area of living marine alga cells was described. The method uses acid-base titration to measure the surface acid/base amount on the surface of alga cells and uses the BET (Brunauer, Emmett, and Teller) equation to estimate the maximum surface acid/base amount, assuming that hydrous cell walls have carbohydrates or other structural compounds which can behave like surface Brönsted acid-base sites due to coordination of environmental H2O molecules. The method was applied to 18 diverse alga species (including 7 diatoms, 2 flagellates, 8 green algae and 1 red alga) maintained in seawater cultures. For the species examined, the surface areas of individual cells ranged from 2.8 x 10(-8) m2 for Nannochloropsis oculata to 690 x 10(-8) m2 for Dunaliella viridis, specific surface areas from 1,030 m2.g-1 for Dunaliella salina to 28,900 m2.g-1 for Pyramidomonas sp. Measurement accuracy was 15.2%. Preliminary studies show that the method may be more promising and accurate than light/electron microscopic measurements for coarse estimation of the surface area of living algae.

Osmosis and Surface Area to Volume Ratio.

ERIC Educational Resources Information Center

Barrett, D. R. B.

1984-01-01

Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)

Water-Surface Elevations, Discharge, and Water-Quality Data for Selected Sites in the Warm Springs Area near Moapa, Nevada

USGS Publications Warehouse

Beck, David A.; Ryan, Roslyn; Veley, Ronald J.; Harper, Donald P.; Tanko, Daron J.

2006-01-01

The U.S. Geological Survey, in cooperation with Southern Nevada Water Authority and the Nevada Division of Water Resources, operates and maintains a surface-water monitoring network of 6 continuous-record stream-flow gaging stations and 11 partial-record stations in the Warm Springs area near Moapa, Nevada. Permanent land-surface bench marks were installed within the Warm Springs area by the Las Vegas Valley Water District, the Southern Nevada Water Authority, and the U.S. Geological Survey to determine water-surface elevations at all network monitoring sites. Vertical datum elevation and horizontal coordinates were established for all bench marks through a series of Differential Global Positioning System surveys. Optical theodolite surveys were made to transfer Differential Global Positioning System vertical datums to reference marks installed at each monitoring site. The surveys were completed in June 2004 and water-surface elevations were measured on August 17, 2004. Water-surface elevations ranged from 1,810.33 feet above North American Vertical Datum of 1988 at a stream-gaging station in the Pederson Springs area to 1,706.31 feet at a station on the Muddy River near Moapa. Discharge and water-quality data were compiled for the Warm Springs area and include data provided by the U.S. Geological Survey, Nevada Division of Water Resources, U.S. Fish and Wildlife Service, Moapa Valley Water District, Desert Research Institute, and Converse Consultants. Historical and current hydrologic data-collection networks primarily are related to changes in land- and water-use activities in the Warm Springs area. These changes include declines in ranching and agricultural use, the exportation of water to other areas of Moapa Valley, and the creation of a national wildlife refuge. Water-surface elevations, discharge, and water-quality data compiled for the Warm Springs area will help identify (1) effects of changing vegetation within the former agricultural lands, (2) effects

Euclidean Wilson loops and minimal area surfaces in lorentzian AdS 3

DOE PAGES

Irrgang, Andrew; Kruczenski, Martin

2015-12-14

The AdS/CFT correspondence relates Wilson loops in N=4 SYM theory to minimal area surfaces in AdS 5 × S 5 space. If the Wilson loop is Euclidean and confined to a plane (t, x) then the dual surface is Euclidean and lives in Lorentzian AdS 3 c AdS 5. In this paper we study such minimal area surfaces generalizing previous results obtained in the Euclidean case. Since the surfaces we consider have the topology of a disk, the holonomy of the flat current vanishes which is equivalent to the condition that a certain boundary Schrödinger equation has all its solutionsmore » anti-periodic. If the potential for that Schrödinger equation is found then reconstructing the surface and finding the area become simpler. In particular we write a formula for the Area in terms of the Schwarzian derivative of the contour. Finally an infinite parameter family of analytical solutions using Riemann Theta functions is described. In this case, both the area and the shape of the surface are given analytically and used to check the previous results.« less

30 CFR 717.14 - Backfilling and grading of road cuts, mine entry area cuts, and other surface work areas.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Backfilling and grading of road cuts, mine entry area cuts, and other surface work areas. 717.14 Section 717.14 Mineral Resources OFFICE OF SURFACE... MINING GENERAL PERFORMANCE STANDARDS § 717.14 Backfilling and grading of road cuts, mine entry area cuts...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2011 CFR

2011-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2014 CFR

2014-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2010 CFR

2010-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2012 CFR

2012-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

40 CFR 761.302 - Proportion of the total surface area to sample.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface into approximately 1 meter square portions and mark the portions so that they are clearly... surfaces contaminated by a single source of PCBs with a uniform concentration, assign each 1 meter square surface a unique sequential number. (i) For three or fewer 1 meter square areas, sample all of the areas...

Surface area of montmorillonite from the dynamic sorption of nitrogen and carbon dioxide

USGS Publications Warehouse

Thomas, Josephus; Bohor, Bruce F.

1968-01-01

Surface area determinations were made on a montmorillonite with various cations emplaced on the exchangeable sites, utilizing nitrogen and carbon dioxide as adsorbates at 77°K and 195°K, respectively, in a dynamic system. From the fraction of a Mississippi montmorillonite less than about 1 μ in size, samples were prepared by replacing the original exchangeable cations with Li+, Na+, K+, Rb+, Cs+, Mg++, Ca++, Ba++, and NH4+, forming a series of homoionic montmorillonite species.Surface areas from 3-point B.E.T. plots (half-hour adsorption points), with nitrogen as the adsorbate, ranged from 61 m2/g for Li-montmorillonite to 138 m2/g for Cs-montmorillonite, thus reflecting a certain degree of nitrogen penetration between layers. Complete penetration should theoretically result in a surface area of over 300 m2/g for this clay with a nitrogen monolayer between each pair of platelets. The experimental data indicate that the extent of penetration is time-dependent and is also a function of the interlayer forces as governed by the size and charge of the replaceable cation. This finding negates the generally accepted concept that nitrogen at 77°K does not penetrate the layers and provides a measure only of the external surface of expandable clay minerals.A further measure of the variation of interlayer forces is provided by the adsorption of carbon dioxide at 195°K. Surface area values ranged from 99 m2/g for Li-montmorillonite to 315 m2/g for Csmontmorillonite. Although the carbon dioxide molecule is larger than the nitrogen molecule, its greater penetration apparently is a result of its being kinetically more energetic (with a larger diffusion coefficient) at its higher adsorption temperature. Similar differences have been found with both adsorbates in the study of microporous substances, such as coal, where activated diffusion is of considerable significance.

Surface Area of Patellar Facets: Inferential Statistics in the Iraqi Population

PubMed Central

Al-Zamili, Zaid; Omar, Rawan

2017-01-01

Background. The patella is the largest sesamoid bone in the body; its three-dimensional complexity necessitates biomechanical perfection. Numerous pathologies occur at the patellofemoral unit which may end in degenerative changes. This study aims to test the presence of statistical correlation between the surface areas of patellar facets and other patellar morphometric parameters. Materials and Methods. Forty dry human patellae were studied. The morphometry of each patella was measured using a digital Vernier Caliper, electronic balance, and image analyses software known as ImageJ. The patellar facetal surface area was correlated with patellar weight, height, width, and thickness. Results. Inferential statistics proved the existence of linear correlation of total facetal surface area and patellar weight, height, width, and thickness. The correlation was strongest for surface area versus patellar weight. The lateral facetal area was found persistently larger than the medial facetal area, the p value was found to be <0.001 (one-tailed t-test) for right patellae, and another significant p value of < 0.001 (one-tailed t-test) was found for left patellae. Conclusion. These data are vital for the restoration of the normal biomechanics of the patellofemoral unit; these are to be consulted during knee surgeries and implant designs and can be of an indispensable anthropometric, interethnic, and biometric value. PMID:28348891

Can static foot posture measurements predict regional plantar surface area?

PubMed

McPoil, Thomas G; Haager, Mathew; Hilt, John; Klapheke, John; Martinez, Ray; VanSteenwyk, Cory; Weber, Nicholas; Cornwall, Mark W; Bade, Michael

2014-12-01

The intent of this study was to determine if the use of a single or combination of static foot posture measurements can be used to predict rearfoot, midfoot, and forefoot plantar surface area in individuals with pronated or normal foot types. Twelve foot measurements were collected on 52 individuals (mean age 25.8 years) with the change in midfoot width used to place subjects in a pronated or normal foot mobility group. Dynamic plantar contact area was collected during walking with a pressure sensor platform. The 12 measures were entered into a stepwise regression analysis to determine the optimal set of measures associated with regional plantar surface area. A two variable model was found to describe the relationship between the foot measurements and forefoot plantar contact area (r(2)=0.79, p<0.0001). A four variable model was found to describe the relationship between the foot measurements and midfoot plantar contact area (r(2)=0.85, p<0.0001) in those individuals with a 1.26cm or greater change in midfoot width. The results indicate that clinicians can use a combination of simple, reliable and time efficient foot measures to explain 79% and 85% of the plantar surface area in the forefoot and midfoot, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

30 CFR 56.17001 - Illumination of surface working areas.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Illumination of surface working areas. 56.17001 Section 56.17001 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination...

Influences of internal resistance and specific surface area of electrode materials on characteristics of electric double layer capacitors

NASA Astrophysics Data System (ADS)

Suda, Yoshiyuki; Mizutani, Akitaka; Harigai, Toru; Takikawa, Hirofumi; Ue, Hitoshi; Umeda, Yoshito

2017-01-01

We fabricated electric double layer capacitors (EDLCs) using particulate and fibrous types of carbon nanomaterials with a wide range of specific surface areas and resistivity as an active material. The carbon nanomaterials used in this study are carbon nanoballoons (CNBs), onion-like carbon (OLC), and carbon nanocoils (CNCs). A commercially used activated carbon (AC) combined with a conductive agent was used as a comparison. We compared the EDLC performance using cyclic voltammetry (CV), galvanostatic charge/discharge testing, and electrochemical impedance spectroscopy (EIS). OLC showed a poor EDLC performance, although it has the lowest resistivity among the carbon nanomaterials. CNB, which has a 1/16 lower specific surface area than AC but higher specific surface area than CNC and OLC, had a higher specific capacitance than CNC and OLC. Moreover, at current densities of 1.5 Ag-1 and larger, the specific capacitance of the EDLC using CNB was almost the same as that using AC. Electrochemical impedance spectroscopy of the EDLCs revealed that the CNB and CNC electrodes had a much lower internal resistance than the AC electrode, which correlated with a low capacitance maintenance factor as the current density increased.

Decoupling the Effects of High Crystallinity and Surface Area on the Photocatalytic Overall Water Splitting over β-Ga2 O3 Nanoparticles by Chemical Vapor Synthesis.

PubMed

Lukic, Sasa; Menze, Jasper; Weide, Philipp; Busser, G Wilma; Winterer, Markus; Muhler, Martin

2017-09-11

Chemical vapor synthesis (CVS) is a unique method to prepare well-defined photocatalyst materials with both large specific surface area and a high degree of crystallinity. The obtained β-Ga 2 O 3 nanoparticles were optimized for photocatalysis by reductive photodeposition of the Rh/CrO x co-catalyst system. The influence of the degree of crystallinity and the specific surface area on photocatalytic aqueous methanol reforming and overall water splitting (OWS) was investigated by synthesizing β-Ga 2 O 3 samples in the temperature range from 1000 °C to 1500 °C. With increasing temperature, the specific surface area and the microstrain were found to decrease, whereas the degree of crystallinity and the crystallite size increased. Whereas the photocatalyst with the highest specific surface area showed the highest aqueous methanol reforming activity, the highest OWS activity was that for the sample with an optimum ratio between high degree of crystallinity and specific surface area. Thus, it was possible to show that the facile aqueous methanol reforming and the demanding OWS have different requirements for high photocatalytic activity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface-Casting Synthesis of Mesoporous Zirconia with a CMK-5-Like Structure and High Surface Area.

PubMed

Gu, Dong; Schmidt, Wolfgang; Pichler, Christian M; Bongard, Hans-Josef; Spliethoff, Bernd; Asahina, Shunsuke; Cao, Zhengwen; Terasaki, Osamu; Schüth, Ferdi

2017-09-04

About 15 years ago, the Ryoo group described the synthesis of CMK-5, a material consisting of a hexagonal arrangement of carbon nanotubes. Extension of the surface casting synthesis to oxide compositions, however, was not possible so far, in spite of many attempts. Here it is demonstrated, that crystalline mesoporous hollow zirconia materials with very high surface areas up to 400 m 2  g -1 , and in selected cases in the form of CMK-5-like, are indeed accessible via such a surface casting process. The key for the successful synthesis is an increased interaction between the silica hard template surface and the zirconia precursor species by using silanol group-rich mesoporous silica as a hard template. The surface areas of the obtained zirconias exceed those of conventionally hard-templated ones by a factor of two to three. The surface casting process seems to be applicable also to other oxide materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical method for measuring the surface area of a threaded fastener

Treesearch

Douglas Rammer; Samuel Zelinka

2010-01-01

This article highlights major aspects of a new optical technique to determine the surface area of a threaded fastener; the theoretical framework has been reported elsewhere. Specifically, this article describes general surface area expressions used in the analysis, details of image acquisition system, and major image processing steps contained within the measurement...

A Comparative Study of Molecular Structure, pKa, Lipophilicity, Solubility, Absorption and Polar Surface Area of Some Antiplatelet Drugs

PubMed Central

Remko, Milan; Remková, Anna; Broer, Ria

2016-01-01

Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor) and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p) level of density functional theory. Computed dissociation constants show that the active metabolites of prodrugs (ticlopidine, clopidogrel and prasugrel) and drugs elinogrel and cangrelor are completely ionized at pH 7.4. Both ticagrelor and its active metabolite are present at pH = 7.4 in neutral undissociated form. The thienopyridine prodrugs ticlopidine, clopidogrel and prasugrel are lipophilic and insoluble in water. Their lipophilicity is very high (about 2.5–3.5 logP values). The polar surface area, with regard to the structurally-heterogeneous character of these antiplatelet drugs, is from very large interval of values of 3–255 Å2. Thienopyridine prodrugs, like ticlopidine, clopidogrel and prasugrel, with the lowest polar surface area (PSA) values, exhibit the largest absorption. A high value of polar surface area (PSA) of cangrelor (255 Å2) results in substantial worsening of the absorption in comparison with thienopyridine drugs. PMID:27007371

Large area, surface discharge pumped, vacuum ultraviolet light source

DOEpatents

Sze, Robert C.; Quigley, Gerard P.

1996-01-01

Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

Large area, surface discharge pumped, vacuum ultraviolet light source

DOEpatents

Sze, R.C.; Quigley, G.P.

1996-12-17

Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

Determining eyeball surface area directly exposed to the effects of external factors.

PubMed

Juliszewski, Tadeusz; Kadłuczka, Filip; Kiełbasa, Paweł

2016-01-01

This article discusses determining the surface area of eyeballs of men and women exposed to the direct effects of external factors in the working environment. For one eye, the mean surface is 172-182 mm(2). The determined surface area can be used in formulas for calculating the exposure of eyeballs to harmful chemical substances in workplace air.

The fraction of total hand surface area involved in young children's outdoor hand-to-object contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

AuYeung, Willa; Canales, Robert A.; Leckie, James O.

2008-11-15

Information on the fraction of total hand surface area touching a contaminated object is necessary in accurately estimating contaminant (e.g., pesticides, pathogens) loadings onto the hands during hand-to-object contacts. While several existing physical-stochastic human exposure models require such surface area data to estimate dermal and non-dietary ingestion exposure, there are very limited data sets. This paper provides statistical distributions of fractional surface areas (FSAs) for children's outdoor hand contacts. These distributions were constructed by combining information collected from two distinct studies exploring children's activity patterns and quantifying hand contact surface area. Results show that for outdoor contacts with 'All Objects',more » a range of 0.13-0.27 captured median FSAs, while a range of 0.12-0.24 captured time-weighted FSAs. Overall, an FSA of 0.31 captured 80-100% of FSAs involved in each child's outdoor hand contacts, depending upon the object of interest. These values are much lower than the often conservative assumptions of up to 1 (i.e., the entire hand) that researchers currently make regarding FSAs involved in indoor and outdoor contacts [USEPA, 1997. Standard operating procedures (SOPs) for residential exposure assessments. Contract no. 68-W6-0030. < (http://www.epa.gov/pesticides/trac/science/trac6a05.pdf)>].« less

Area Estimation of Deep-Sea Surfaces from Oblique Still Images

PubMed Central

Souto, Miguel; Afonso, Andreia; Calado, António; Madureira, Pedro; Campos, Aldino

2015-01-01

Estimating the area of seabed surfaces from pictures or videos is an important problem in seafloor surveys. This task is complex to achieve with moving platforms such as submersibles, towed or remotely operated vehicles (ROV), where the recording camera is typically not static and provides an oblique view of the seafloor. A new method for obtaining seabed surface area estimates is presented here, using the classical set up of two laser devices fixed to the ROV frame projecting two parallel lines over the seabed. By combining lengths measured directly from the image containing the laser lines, the area of seabed surfaces is estimated, as well as the camera’s distance to the seabed, pan and tilt angles. The only parameters required are the distance between the parallel laser lines and the camera’s horizontal and vertical angles of view. The method was validated with a controlled in situ experiment using a deep-sea ROV, yielding an area estimate error of 1.5%. Further applications and generalizations of the method are discussed, with emphasis on deep-sea applications. PMID:26177287

Specific surface area as a maturity index of lunar fines

NASA Technical Reports Server (NTRS)

Gammage, R. B.; Holmes, H. F.

1975-01-01

Mature surface fines have an equilibrium specific surface area of about 0.6 sq m/g the equivalent mean particle size being about 3 microns. The adsorption behavior of inert gases (reversible isotherms) indicates that the particles are also nonporous in the size range of pores from 10 to 3000 A. Apparently, in mature soils there is a balance in the forces which cause fining, attrition, pore filling, and growth of lunar dust grains. Immature, lightly irradiated soils usually have coarser grains which reduce in size as aging proceeds. The specific surface area, determined by nitrogen or krypton sorption at 77 K, is a valuable index of soil maturity.

Method of measuring interface area of activated carbons in condensed phase

NASA Astrophysics Data System (ADS)

Dmitriyev, D. S.; Agafonov, D. V.; Kiseleva, E. A.; Mikryukova, M. A.

2018-01-01

In this work, we investigated the correlation between the heat of wetting of super-capacitor electrode material (activated carbon) with condensed phases (electrolytes based on homologous series of phosphoric acid esters) and the capacity of the supercapacitor. The surface area of the electrode-electrolyte interface was calculated according to the obtained correlations using the conventional formula for calculating the capacitance of a capacitor.

Controlling the Electrochemically Active Area of Carbon Fiber Microelectrodes by the Electrodeposition and Selective Removal of an Insulating Photoresist

PubMed Central

Lambie, Bradley A.; Orwar, Owe; Weber, Stephen G.

2008-01-01

A new and simple method permits control of the electrochemically active area of a carbon fiber microelectrode. An electrophoretic photoresist insulates the 10 μm diameter carbon fiber microelectrodes. Photolysis of the photoresist followed by immersion of the exposed area into a developing solution reveals electroactive carbon fiber surface. The electroactive surface area exposed can be controlled with a good degree of reproducibility. PMID:16841943

Active Structures as Deduced from Geomorphic Features: A case in Hsinchu Area, northwestern Taiwan

NASA Astrophysics Data System (ADS)

Chen, Y.; Shyu, J.; Ota, Y.; Chen, W.; Hu, J.; Tsai, B.; Wang, Y.

2002-12-01

Hsinchu area is located in the northwestern Taiwan, the fold-and thrust belt created by arc-continent collision between Eurasian and Philippine. Since the collision event is still ongoing, the island is tectonically active and full of active faults. According to the historical records, some of the faults are seismically acting. In Hsinchuarea two active faults, the Hsinchu and Hsincheng, have been previously mapped. To evaluate the recent activities, we studied the related geomorphic features by using newly developed Digital Elevation Model (DEM), the aerial photos and field investigation. Geologically, both of the faults are coupled with a hanging wall anticline. The anticlines are recently active due to the deformation of the geomorphic surfaces. The Hsinchu fault system shows complicate corresponding scarps, distributed sub-parallel to the fault trace previously suggested by projection of subsurface geology. This is probably caused by its strike-slip component tearing the surrounding area along the main trace. The scarps associated with the Hsincheng fault system are rather simple and unique. It offsets a flight of terraces all the way down to recent flood plain, indicating its long lasting activity. One to two kilometers to east of main trace a back-thrust is found, showing coupled vertical surface offsets with the main fault. The striking discovery in this study is that the surface deformation is only distributed in the southern bank of Touchien river, also suddenly decreasing when crossing another tear fault system, which is originated from Hsincheng fault in the west and extending southeastward parallel to the Touchien river. The strike-slip fault system mentioned above not only bisects the Hsinchu fault, but also divides the Hsincheng fault into segments. The supporting evidence found in this study includes pressure ridges and depressions. As a whole, the study area is tectonically dominated by three active fault systems and two actively growing anticlines

The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

NASA Astrophysics Data System (ADS)

Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

2013-09-01

Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na2Ti2O5·H2O) particles (W = 9-12 nm and L = 82-115 nm) and rice like pure anatase-TNR particles (W = 8-13 nm and L = 81-134 nm) are obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = -2.82 (P25-TiO2), -13.5 (TNT) and -22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C9H10ClN5O2) degradation to CO2 formation under UV irradiation because of its largest surface area 176 m2 g-1 among the catalysts studied.

Saturn's Titan: Surface change, ammonia, and implications for atmospheric and tectonic activity

USGS Publications Warehouse

Nelson, R.M.; Kamp, L.W.; Matson, D.L.; Irwin, P.G.J.; Baines, K.H.; Boryta, M.D.; Leader, F.E.; Jaumann, R.; Smythe, W.D.; Sotin, Christophe; Clark, R.N.; Cruikshank, D.P.; Drossart, P.; Pearl, J.C.; Hapke, B.W.; Lunine, J.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, R.Y.; McCord, T.B.; Mennella, V.; Nicholson, P.D.; Sicardy, B.

2009-01-01

Titan is known to have a young surface. Here we present evidence from the Cassini Visual and Infrared Mapping Spectrometer that it is currently geologically active. We report that changes in the near-infrared reflectance of a 73,000 km2 area on Titan (latitude 26° S, longitude 78° W) occurred between July 2004 and March of 2006. The reflectance of the area increased by a factor of two between July 2004 and March–April 2005; it then returned to the July 2004 level by November 2005. By late December 2005 the reflectance had surged upward again, establishing a new maximum. Thereafter, it trended downward for the next three months. Detailed spectrophotometric analyses suggest these changes happen at or very near the surface. The spectral differences between the region and its surroundings rule out changes in the distribution of the ices of reasonably expected materials such as H2O, CO2, and CH4 as possible causes. Remarkably, the change is spectrally consistent with the deposition and removal of NH3 frost over a water ice substrate. NH3 has been proposed as a constituent of Titan's interior and has never been reported on the surface. The detection of NH3 frost on the surface might possibly be explained by episodic effusive events occur which bring juvenile ammonia from the interior to the surface. If so, its decomposition would feed nitrogen to the atmosphere now and in the future. The lateral extent of the region exceeds that of active areas on the Earth (Hawaii) or Io (Loki).

Age Differences in Prefrontal Surface Area and Thickness in Middle Aged to Older Adults.

PubMed

Dotson, Vonetta M; Szymkowicz, Sarah M; Sozda, Christopher N; Kirton, Joshua W; Green, Mackenzie L; O'Shea, Andrew; McLaren, Molly E; Anton, Stephen D; Manini, Todd M; Woods, Adam J

2015-01-01

Age is associated with reductions in surface area and cortical thickness, particularly in prefrontal regions. There is also evidence of greater thickness in some regions at older ages. Non-linear age effects in some studies suggest that age may continue to impact brain structure in later decades of life, but relatively few studies have examined the impact of age on brain structure within middle-aged to older adults. We investigated age differences in prefrontal surface area and cortical thickness in healthy adults between the ages of 51 and 81 years. Participants received a structural 3-Tesla magnetic resonance imaging scan. Based on a priori hypotheses, primary analyses focused on surface area and cortical thickness in the dorsolateral prefrontal cortex, anterior cingulate cortex, and orbitofrontal cortex. We also performed exploratory vertex-wise analyses of surface area and cortical thickness across the entire cortex. We found that older age was associated with smaller surface area in the dorsolateral prefrontal and orbitofrontal cortices but greater cortical thickness in the dorsolateral prefrontal and anterior cingulate cortices. Vertex-wise analyses revealed smaller surface area in primarily frontal regions at older ages, but no age effects were found for cortical thickness. Results suggest age is associated with reduced surface area but greater cortical thickness in prefrontal regions during later decades of life, and highlight the differential effects age has on regional surface area and cortical thickness.

Influence of specific surface area on coal dust explosibility using the 20-L chamber.

PubMed

Zlochower, Isaac A; Sapko, Michael J; Perera, Inoka E; Brown, Connor B; Harris, Marcia L; Rayyan, Naseem S

2018-07-01

The relationship between the explosion inerting effectiveness of rock dusts on coal dusts, as a function of the specific surface area (cm 2 /g) of each component is examined through the use of 20-L explosion chamber testing. More specifically, a linear relationship is demonstrated for the rock dust to coal dust (or incombustible to combustible) content of such inerted mixtures with the specific surface area of the coal and the inverse of that area of the rock dust. Hence, the inerting effectiveness, defined as above, is more generally linearly dependent on the ratio of the two surface areas. The focus on specific surface areas, particularly of the rock dust, provide supporting data for minimum surface area requirements in addition to the 70% less than 200 mesh requirement specified in 30 CFR 75.2.

High surface area synthesis, electrochemical activity, and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Chhina, H.; Campbell, S.; Kesler, O.

The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 °C and compared to that of HiSpec 4000™ Pt/Vulcan XC-72R in 0.5 M H 2SO 4. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000™. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization.

Thermal Desorption Analysis of Effective Specific Soil Surface Area

NASA Astrophysics Data System (ADS)

Smagin, A. V.; Bashina, A. S.; Klyueva, V. V.; Kubareva, A. V.

2017-12-01

A new method of assessing the effective specific surface area based on the successive thermal desorption of water vapor at different temperature stages of sample drying is analyzed in comparison with the conventional static adsorption method using a representative set of soil samples of different genesis and degree of dispersion. The theory of the method uses the fundamental relationship between the thermodynamic water potential (Ψ) and the absolute temperature of drying ( T): Ψ = Q - aT, where Q is the specific heat of vaporization, and a is the physically based parameter related to the initial temperature and relative humidity of the air in the external thermodynamic reservoir (laboratory). From gravimetric data on the mass fraction of water ( W) and the Ψ value, Polyanyi potential curves ( W(Ψ)) for the studied samples are plotted. Water sorption isotherms are then calculated, from which the capacity of monolayer and the target effective specific surface area are determined using the BET theory. Comparative analysis shows that the new method well agrees with the conventional estimation of the degree of dispersion by the BET and Kutilek methods in a wide range of specific surface area values between 10 and 250 m2/g.

Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

PubMed Central

Xue, Chao-Hua; Jia, Shun-Tian; Zhang, Jing; Ma, Jian-Zhong

2010-01-01

This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted. PMID:27877336

Morphological abnormalities in prefrontal surface area and thalamic volume in attention deficit/hyperactivity disorder.

PubMed

Batty, Martin J; Palaniyappan, Lena; Scerif, Gaia; Groom, Madeleine J; Liddle, Elizabeth B; Liddle, Peter F; Hollis, Chris

2015-08-30

Although previous morphological studies have demonstrated abnormalities in prefrontal cortical thickness in children with attention deficit/hyperactivity disorder (ADHD), studies investigating cortical surface area are lacking. As the development of cortical surface is closely linked to the establishment of thalam-ocortical connections, any abnormalities in the structure of the thalamus are likely to relate to altered cortical surface area. Using a clinically well-defined sample of children with ADHD (n = 25, 1 female) and typically developing controls (n = 24, 1 female), we studied surface area across the cortex to determine whether children with ADHD had reduced thalamic volume that related to prefrontal cortical surface area. Relative to controls, children with ADHD had a significant reduction in thalamic volume and dorsolateral prefrontal cortical area in both hemispheres. Furthermore, children with ADHD with smaller thalamic volumes were found to have greater reductions in surface area, a pattern not evident in the control children. Our results are further evidence of reduced lateral prefrontal cortical area in ADHD. Moreover, for the first time, we have also shown a direct association between thalamic anatomy and frontal anatomy in ADHD, suggesting the pathophysiological process that alters surface area maturation is likely to be linked to the development of the thalamus. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Assessing the Increase in Specific Surface Area for Electrospun Fibrous Network due to Pore Induction.

PubMed

Katsogiannis, Konstantinos Alexandros G; Vladisavljević, Goran T; Georgiadou, Stella; Rahmani, Ramin

2016-10-26

The effect of pore induction on increasing electrospun fibrous network specific surface area was investigated in this study. Theoretical models based on the available surface area of the fibrous network and exclusion of the surface area lost due to fiber-to-fiber contacts were developed. The models for calculation of the excluded area are based on Hertzian, Derjaguin-Muller-Toporov (DMT), and Johnson-Kendall-Roberts (JKR) contact models. Overall, the theoretical models correlated the network specific surface area to the material properties including density, surface tension, Young's modulus, Poisson's ratio, as well as network physical properties, such as density and geometrical characteristics including fiber radius, fiber aspect ratio and network thickness. Pore induction proved to increase the network specific surface area up to 52%, compared to the maximum surface area that could be achieved by nonporous fiber network with the same physical properties and geometrical characteristics. The model based on Johnson-Kendall-Roberts contact model describes accurately the fiber-to-fiber contact area under the experimental conditions used for pore generation. The experimental results and the theoretical model based on Johnson-Kendall-Roberts contact model show that the increase in network surface area due to pore induction can reach to up to 58%.

Exposure to particle number, surface area and PM concentrations in pizzerias

NASA Astrophysics Data System (ADS)

Buonanno, G.; Morawska, L.; Stabile, L.; Viola, A.

2010-10-01

The aim of this work was to quantify exposure to particles emitted by wood-fired ovens in pizzerias. Overall, 15 microenvironments were chosen and analyzed in a 14-month experimental campaign. Particle number concentration and distribution were measured simultaneously using a Condensation Particle Counter (CPC), a Scanning Mobility Particle Sizer (SMPS), an Aerodynamic Particle Sizer (APS). The surface area and mass distributions and concentrations, as well as the estimation of lung deposition surface area and PM 1 were evaluated using the SMPS-APS system with dosimetric models, by taking into account the presence of aggregates on the basis of the Idealized Aggregate (IA) theory. The fraction of inhaled particles deposited in the respiratory system and different fractions of particulate matter were also measured by means of a Nanoparticle Surface Area Monitor (NSAM) and a photometer (DustTrak DRX), respectively. In this way, supplementary data were obtained during the monitoring of trends inside the pizzerias. We found that surface area and PM 1 particle concentrations in pizzerias can be very high, especially when compared to other critical microenvironments, such as the transport hubs. During pizza cooking under normal ventilation conditions, concentrations were found up to 74, 70 and 23 times higher than background levels for number, surface area and PM 1, respectively. A key parameter is the oven shape factor, defined as the ratio between the size of the face opening in respect to the diameter of the semicircular oven door, and particular attention must also be paid to hood efficiency.

Long-term studies on the effects of nonvolatile organic compounds on porous media surface areas.

PubMed

Khachikian, Crist S; Harmon, Thomas C

2002-01-01

This paper investigates the long-term behavior of porous media contaminated by nonvolatile organic compounds (NVOC) in terms of specific interfacial surface area. Specifically, a natural sand, Moffett sand (MS), was contaminated with naphthalene and the surface area was measured repeatedly over time using nitrogen adsorption-desorption techniques. A field-contaminated sand affected by lamp-black material (LB) from former manufactured gas plant operations was also studied. Lampblack is a carbonaceous skeleton containing polycyclic aromatic hydrocarbons (PAHs) and other hydrocarbons. It is hypothesized that soils contaminated by these types of chemicals will exhibit significantly less surface area than their clean counterparts. The surface areas for the contaminated MS samples increased toward their clean-MS values during the 700-h aging period, but achieved the clean values only after pentane extraction or heating at 60 degrees C. Heating at 50 degrees C failed to achieve a similar recovery of the clean-MS surface area value. Nonspecific mass loss tracked the increase in surface area as indirect evidence that naphthalene loss was the cause of the surface area increase. For the LB samples, aging at 100 degrees C produced a slight decrease in surface area and mass while aging at 250 degrees C caused the surface area to increase roughly threefold while the mass decreased by approximately 1%. These results suggest that, under moderate heating and over the time scale of this investigation, there is a redistribution of the complex contaminant mixture on the solid matrix. Greater temperatures remove mass more efficiently and therefore exhibited the surface area increase expected in this experiment.

Polyaniline nanofibers with a high specific surface area and an improved pore structure for supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Hailing; Li, Xingwei; Wang, Gengchao

2015-10-01

Polyaniline (PANI) with a high specific surface area and an improved pore structure (HSSA-PANI) has been prepared by using a facile method, treating PANI nanofibers with chloroform (CHCl3), and its structure, morphology and pore structure are investigated. The specific surface area and pore volume of HSSA-PANI are 817.3 m2 g-1 and 0.6 cm3 g-1, and those of PANI are 33.6 m2 g-1 and 0.2 cm3 g-1. As electrode materials, a large specific surface area and pore volume can provide high electroactive regions, accelerate the diffusion of ions, and mitigate the electrochemical degradation of active materials. Compared with PANI, the capacity retention rate of HSSA-PANI is 90% with a growth of current density from 5.0 to 30 A g-1, and that of PANI is 29%. At a current density of 30 A g-1, the specific capacitance of HSSA-PANI still reaches 278.3 F g-1, and that of PANI is 86.7 F g-1. At a current density of 5.0 A g-1, the capacitance retention of HSSA-PANI is 53.1% after 2000 cycles, and that of PANI electrode is only 28.1%.

30 CFR 905.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 905.764 Section 905.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE CALIFORNIA § 905.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

30 CFR 910.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 910.764 Section 910.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE GEORGIA § 910.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

30 CFR 912.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 912.764 Section 912.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE IDAHO § 912.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

30 CFR 903.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... surface coal mining operations. 903.764 Section 903.764 Mineral Resources OFFICE OF SURFACE MINING... WITHIN EACH STATE ARIZONA § 903.764 Process for designating areas unsuitable for surface coal mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface Coal...

Surface area of vermiculite with nitrogen and carbon dioxide as adsorbates

USGS Publications Warehouse

Thomas, Josephus; Bohor, Bruce F.

1969-01-01

Surface-area studies were made on several homoionic vermiculites with both nitrogen and carbon dioxide as adsorbates. These studies show that only very slight penetration occurs between individual vermiculite platelets. This is in contrast to an earlier investigation of montmorillonite where it was found that the degree of penetration between layers is quite high, particularly for carbon dioxide, and is governed by the size and charge of the interlayer cation. The inability of these adsorbates to penetrate substantially between vermiculite platelets is due primarily to this mineral's high surface-charge density.The extent of penetration of nitrogen and carbon dioxide at the edges of vermiculite platelets, though slight, is influenced by the coordinated water retained within the sample at a given degassing temperature. Forces between layers are weakened with increasing water content, which permits slightly greater penetration by adsorbate gases. Thus, the surface area of vermiculite, as determined by gas adsorption, is larger than the calculated external surface area based upon particle size and shape considerations. In addition, "extra" surface is provided by the lifting and scrolling of terminal platelets. These morphological features are shown in scanning electron micrographs of a naturally occuring vermiculite.

Assessment of Surface Area Characteristics of Dental Implants with Gradual Bioactive Surface Treatment

NASA Astrophysics Data System (ADS)

Czan, Andrej; Babík, Ondrej; Miklos, Matej; Záušková, Lucia; Mezencevová, Viktória

2017-10-01

Since most of the implant surface is in direct contact with bone tissue, shape and integrity of said surface has great influence on successful osseointegration. Among other characteristics that predetermine titanium of different grades of pureness as ideal biomaterial, titanium shows high mechanical strength making precise miniature machining increasingly difficult. Current titanium-based implants are often anodized due to colour coding. This anodized layer has important functional properties for right usage and also bio-compatibility of dental implants. Physical method of anodizing and usage of anodizing mediums has a significant influence on the surface quality and itself functionality. However, basic requirement of the dental implant with satisfactory properties is quality of machined surface before anodizing. Roughness, for example, is factor affecting of time length of anodizing operation and so whole productivity. The paper is focused on monitoring of surface and area characteristics, such as roughness or surface integrity after different cutting conditions of miniature machining of dental implants and their impact on suitability for creation of satisfactory anodized layer with the correct biocompatible functional properties.

Relationship among land surface temperature and LUCC, NDVI in typical karst area.

PubMed

Deng, Yuanhong; Wang, Shijie; Bai, Xiaoyong; Tian, Yichao; Wu, Luhua; Xiao, Jianyong; Chen, Fei; Qian, Qinghuan

2018-01-12

Land surface temperature (LST) can reflect the land surface water-heat exchange process comprehensively, which is considerably significant to the study of environmental change. However, research about LST in karst mountain areas with complex topography is scarce. Therefore, we retrieved the LST in a karst mountain area from Landsat 8 data and explored its relationships with LUCC and NDVI. The results showed that LST of the study area was noticeably affected by altitude and underlying surface type. In summer, abnormal high-temperature zones were observed in the study area, perhaps due to karst rocky desertification. LSTs among different land use types significantly differed with the highest in construction land and the lowest in woodland. The spatial distributions of NDVI and LST exhibited opposite patterns. Under the spatial combination of different land use types, the LST-NDVI feature space showed an obtuse-angled triangle shape and showed a negative linear correlation after removing water body data. In summary, the LST can be retrieved well by the atmospheric correction model from Landsat 8 data. Moreover, the LST of the karst mountain area is controlled by altitude, underlying surface type and aspect. This study provides a reference for land use planning, ecological environment restoration in karst areas.

Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

PubMed

Zaki, Mohamed F; Tawfik, Salah M

2014-01-01

Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

High-surface-area architectures for improved charge transfer kinetics at the dark electrode in dye-sensitized solar cells.

PubMed

Hoffeditz, William L; Katz, Michael J; Deria, Pravas; Martinson, Alex B F; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

2014-06-11

Dye-sensitized solar cell (DSC) redox shuttles other than triiodide/iodide have exhibited significantly higher charge transfer resistances at the dark electrode. This often results in poor fill factor, a severe detriment to device performance. Rather than moving to dark electrodes of untested materials that may have higher catalytic activity for specific shuttles, the surface area of platinum dark electrodes could be increased, improving the catalytic activity by simply presenting more catalyst to the shuttle solution. A new copper-based redox shuttle that experiences extremely high charge-transfer resistance at conventional Pt dark electrodes yields cells having fill-factors of less than 0.3. By replacing the standard Pt dark electrode with an inverse opal Pt electrode fabricated via atomic layer deposition, the dark electrode surface area is boosted by ca. 50-fold. The resulting increase in interfacial electron transfer rate (decrease in charge-transfer resistance) nearly doubles the fill factor and therefore the overall energy conversion efficiency, illustrating the utility of this high-area electrode for DSCs.

Polybrominated diphenyl ethers in surface soils from e-waste recycling areas and industrial areas in South China: concentration levels, congener profile, and inventory.

PubMed

Gao, Shutao; Hong, Jianwen; Yu, Zhiqiang; Wang, Jingzhi; Yang, Guoyi; Sheng, Guoying; Fu, Jiamo

2011-12-01

Polybrominated diphenyl ethers (PBDEs) were determined in 60 surface soils from two e-waste recycling sites (Qingyuan and Guiyu, China) and their surrounding areas to assess the extent and influence of PBDEs from e-waste recycling sites on the surrounding areas. A total of 32 surface soils from industrial areas in South China were also investigated for comparison. The mean concentrations of total PBDEs in the e-waste recycling sites of Guiyu and Qingyuan were 2,909 and 3,230 ng/g dry weight, respectively, whereas the PBDE concentrations decreased dramatically (1-2 orders of magnitude) with increasing distance from the recycling site, suggesting that the e-waste recycling activities were the major source of PBDEs in the surrounding areas. Decabromodiphenyl ethers accounted for 77.0 to 85.8% of total PBDEs in e-waste recycling areas, whereas it accounted for 90.2% in industrial areas. Principal component analysis showed that the major source of PBDEs in e-waste recycling areas were a combination of penta-, octa-, and deca-BDE commercial formulations, whereas deca-BDE commercial formulations were the major source of PBDE congeners in industrial areas. The inventories of PBDEs gave preliminary estimates of 6.22 tons and 13.4 tons for the e-waste recycling areas and industrial areas. The results suggested that significantly higher PBDEs in the e-waste recycling sites have already affected surrounding areas negatively within a relatively large distance. Because of the environmental persistence, bioaccumulation, and toxicity of PBDEs, improving the recycling techniques employed at such facilities and developing e-waste management policies are necessary. Copyright © 2011 SETAC.

Determinants of aerosol lung-deposited surface area variation in an urban environment.

PubMed

Reche, Cristina; Viana, Mar; Brines, Mariola; Pérez, Noemí; Beddows, David; Alastuey, Andrés; Querol, Xavier

2015-06-01

Ultrafine particles are characterized by a high surface area per mass. Particle surface has been reported to play a significant role in determining the toxicological activity of ultrafine particles. In light of this potential role, the time variation of lung deposited surface area (LDSA) concentrations in the alveolar region was studied at the urban background environment of Barcelona (Spain), aiming to asses which processes and sources govern this parameter. Simultaneous data on Black Carbon (BC), total particle number (N) and particle number size distribution were correlated with LDSA. Average LDSA concentrations in Barcelona were 37 ± 26 μm(2)cm(-3), levels which seem to be characteristic for urban environments under traffic influence across Europe. Results confirm the comparability between LDSA data provided by the online monitor and those calculated based on particle size distributions (by SMPS), and reveal that LDSA concentrations are mainly influenced by particles in the size range 50-200 nm. A set of representative daily cycles for LDSA concentrations was obtained by means of a k-means cluster technique. The contribution of traffic emissions to daily patterns was evidenced in all the clusters, but was quantitatively different. Traffic events under stable atmospheric conditions increased mean hourly background LDSA concentrations up to 6 times, attaining levels higher than 200 μm(2)cm(-3). However, under warm and relatively clean atmospheric conditions, the traffic rush hour contribution to the daily LDSA mean appeared to be lower and the contribution of new urban particle formation events (by photochemically induced nucleation) was detected. These nucleation events were calculated to increase average background LDSA concentrations by 15-35% (maximum LDSA levels=45-50 μm(2)cm(-3)). Thereby, it may be concluded that in the urban background of Barcelona road traffic is the main source increasing the aerosol surface area which can deposit on critical

Decadal changes of surface elevation over permafrost area estimated using reflected GPS signals

NASA Astrophysics Data System (ADS)

Liu, Lin; Larson, Kristine M.

2018-02-01

Conventional benchmark-based survey and Global Positioning System (GPS) have been used to measure surface elevation changes over permafrost areas, usually once or a few times a year. Here we use reflected GPS signals to measure temporal changes of ground surface elevation due to dynamics of the active layer and near-surface permafrost. Applying the GPS interferometric reflectometry technique to the multipath signal-to-noise ratio data collected by a continuously operating GPS receiver mounted deep in permafrost in Barrow, Alaska, we can retrieve the vertical distance between the antenna and reflecting surface. Using this unique kind of observables, we obtain daily changes of surface elevation during July and August from 2004 to 2015. Our results show distinct temporal variations at three timescales: regular thaw settlement within each summer, strong interannual variability that is characterized by a sub-decadal subsidence trend followed by a brief uplift trend, and a secular subsidence trend of 0.26 ± 0.02 cm year-1 during 2004 and 2015. This method provides a new way to fully utilize data from continuously operating GPS sites in cold regions for studying dynamics of the frozen ground consistently and sustainably over a long time.

Surface Texture-Induced Enhancement of Optical and Photoelectrochemical Activity of Cu2ZnSnS4 Photocathodes

NASA Astrophysics Data System (ADS)

Sarswat, Prashant K.; Deka, Nipon; Jagan Mohan Rao, S.; Free, Michael L.; Kumar, Gagan

2017-08-01

The objective of this work is to understand and improve the photocatalytic activity of Cu2ZnSnS4 (CZTS) through postgrowth modification techniques to create surface textures. This objective can be achieved using a combination of solvents, etching agents, and anodization techniques. One of the most effective surface treatments for enhancing the surface properties of photovoltaic materials is formation of nanoscale flakes, although other surface modifications were also evaluated. The superior performance of textured films can be attributed to enhanced surface area of absorber material exposed to electrolyte, ZnS deficiency, and high catalytic activity due to reduced charge-transfer resistance. Fine-tuning of ion flux and electrolyte stoichiometry can be used to create a controlled growth algorithm for CZTS thin films. The resulting information can be utilized to optimize film properties. The utility of nanostructured or engineered surfaces was evaluated using photoelectrochemical measurements. Finite-difference time-domain (FDTD)-assisted simulations were conducted for selected texturing, revealing enhanced surface area of absorbing medium that ultimately resulted in greater power loss of light in the medium.

Excess surface area in bioelectrochemical systems causes ion transport limitations.

PubMed

Harrington, Timothy D; Babauta, Jerome T; Davenport, Emily K; Renslow, Ryan S; Beyenal, Haluk

2015-05-01

We investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200 mM increased current linearly up to a total of +273% vs. 0 mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200 mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un-colonized surface area remained even after steady-state current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non-zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport-limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant. © 2014 Wiley Periodicals, Inc.

High surface area aerogels for energy storage and efficiency

NASA Astrophysics Data System (ADS)

Maloney, Ryan Patrick

ADAI are demonstrated in a third-generation prototypical thermoelectric generator for automotive waste heat recovery. The second chapter then details two different aerogel-based materials for electrochemical energy storage. It begins with lithium titanate aerogel, which takes advantage of the high surface area of the aerogel morphology to display a batt-cap behavior. This should allow the lithium titanate aerogel to perform at higher rates than would normally be expected for the bulk oxide material. Additionally, the flexibility of the sol-gel process is demonstrated through the incorporation of electrically conductive high-surface area exfoliated graphite nanoplatelets in the oxide. The last section describes the characterization of a LiMn2O 4 spinel coated carbon nanofoam in a non-aqueous electrolyte. The short diffusion path, high surface area and intimately wired architecture of the nanofoam allows the oxide to retain its capacity at significantly higher rates when compared with literature values for the bulk oxide. Additionally, the nanometric length scale improves cycle life, and the high surface area dramatically increases the insertion capacity by providing a higher concentration of surface defects. Taken together, it is clear that aerogels are an extremely attractive class of material for applications pertaining to energy and efficiency, and further research in this area will provide valuable solutions for pressing societal needs. (Abstract shortened by UMI.).

Gill area, permeability and Na+ ,K+ -ATPase activity as a function of size and salinity in the blue crab, Callinectes sapidus.

PubMed

Li, Tiandao; Roer, Robert; Vana, Matthew; Pate, Susan; Check, Jennifer

2006-03-01

Juvenile blue crabs, Callinectes sapidus, extensively utilize oligohaline and freshwater regions of the estuary. With a presumptively larger surface-area-to-body weight ratio, juvenile crabs could experience osmo- and ionoregulatory costs well in excess of that of adults. To test this hypothesis, crabs ranging over three orders of magnitude in body weight were acclimated to either sea water (1,000 mOsm) or dilute sea water (150 mOsm), and gill surface area, water and sodium permeabilities (calculated from the passive efflux of 3H2O and 22Na+), gill Na+, K+ -ATPase activity and expression were measured. Juveniles had a relatively larger gill surface area; weight-specific gill surface area decreased with body weight. Weight-specific water and sodium fluxes also decreased with weight, but not to the same extent as gill surface area; thus juveniles were able to decrease gill permeability slightly more than adults upon acclimation to dilute media. Crabs < 5 g in body weight had markedly higher activities of gill Na+ ,K+ -ATPase than crabs > 5 g in both posterior and anterior gills. Acclimation to dilute medium induced increased expression of Na+, K+ -ATPase and enzyme activity, but the increase was not as great in juveniles as in larger crabs. The increased weight-specific surface area for water gain and salt loss for small crabs in dilute media presents a challenge that is incompletely compensated by reduced permeability and increased affinity of gill Na+, K+ -ATPase for Na+. Juveniles maintain osmotic and ionic homeostasis by the expression and utilization of extremely high levels of gill Na+, K+ -ATPase, in posterior, as well as in anterior, gills. Copyright 2006 Wiley-Liss, Inc.

Natural radioactivity in surface soil samples from dwelling areas in Tehran city, Iran.

PubMed

Asgharizadeh, F; Ghannadi, M; Samani, A B; Meftahi, M; Shalibayk, M; Sahafipour, S A; Gooya, E S

2013-09-01

The study was carried out to determine radioactivity concentrations in surface soil samples of the city of Tehran and associated potential radiological hazards. The natural radionuclide ((226)Ra, (232)Th and (40)K) contents were determined for 50 locations throughout the geological surface formations in a representative area in the city of Tehran, Iran, using high-resolution gamma-spectrometric analysis. The range of activity concentrations of (226)Ra, (232)Th and (40)K in the soil from the studied areas varies from 30.5±0.6 to 45.4±0.9, 27.3±0.5 to 57.1±1.1 and 328.0±4.6 to 768.5±13.4 Bq kg(-1) with overall mean values of 38.8±0.7, 43.4±0.8 and 555.1±8.9 Bq kg(-1), respectively. The mean radium equivalent activity, external hazard index, internal hazard index to quantify the internal exposure to radon and its daughter products, as well as the gamma activity concentration index for each sample are 143.6±4.6 Bq kg(-1), 0.39, 0.49 and 0.53, respectively. The average estimated radium equivalent is comparable with reported values for many countries in the world. Therefore, these areas may not pose radiological risks to the inhabitants due to harmful effects of the ionising radiation from the natural radioactivity in soil. The calculated average external and internal hazard indexes were found to be less than unity, as a recommended safe level. Estimates of the measured radionuclide content have been made for calculating the absorbed dose rate in the outdoor air at 1 m above the ground level. The absorbed dose rates resulting from those concentrations ranged from 48.1 to 88.7 nGy h(-1). Assuming a 20 % occupancy factor proposed by UNSCEAR, 2000, the corresponding effective dose rates in outdoor air equivalent to the population were calculated to be between 0.06 and 0.11 mSv y(-1). The measurement results and calculated values obtained from this study indicate that the dwelling areas in Tehran city, Iran, have background radioactivity levels within natural

Increasing biochar surface area: effects of various milling

USDA-ARS?s Scientific Manuscript database

Biochar produced from corn stover is a renewable, plentiful source of carbon that is a potential substitute for carbon black as rubber composite filler and also as binder/filter media for water or beverage purification applications. However, to be successful in these applications, the surface area o...

Geohydrology and susceptibility of major aquifers to surface contamination in Alabama, area 7

USGS Publications Warehouse

Mooty, W.S.

1987-01-01

The geohydrology and susceptibility of the seven major aquifers to surface contamination in Area 7 - Bibb, Dallas, Hale, Perry, and Wilcox Counties, are described. Aquifers in the northern part of the study area are in Paleozoic limestones and dolomite formations. Deposits in the central part of the study area are predominately of Cretaceous age and contain the Coker, Gordo, and Eutaw aquifers. Although the southern part of the study area has many deposits of Tertiary age, the Ripley Formation of Cretaceous age is the major aquifer. Contamination of any of the major aquifers is improbable because the majority of the recharge area for the primary aquifers is woodland, pasture, or farmland. Downdip from their outcrops, the major aquifers in the study area are protected from land surface contamination by relatively impermeable layers of clay and chalk. The aquifers that are highly susceptible to contamination are the ones in the limestone and dolomite formations in northern Bibb County. Sinkholes exist in the recharge area of these formations and could provide a direct link for contaminates from the land surface to the water table. An area northeast of the Selma well field is also highly susceptible to contamination. The Eutaw Formation in this area is overlain by alluvial deposits that could increase recharge to the aquifer by slowing the runoff rate of surface water. (USGS)

Technology of surface wastewater purification, including high-rise construction areas

NASA Astrophysics Data System (ADS)

Tsyba, Anna; Skolubovich, Yury

2018-03-01

Despite on the improvements in the quality of high-rise construction areas and industrial wastewater treatment, the pollution of water bodies continues to increase. This is due to the organized and unorganized surface untreated sewage entry into the reservoirs. The qualitative analysis of some cities' surface sewage composition is carried out in the work. Based on the published literature review, the characteristic contamination present in surface wastewater was identified. The paper proposes a new technology for the treatment of surface sewage and presents the results of preliminary studies.

Evaluation of the Biological Sampling Kit (BiSKit) for Large-Area Surface Sampling

PubMed Central

Buttner, Mark P.; Cruz, Patricia; Stetzenbach, Linda D.; Klima-Comba, Amy K.; Stevens, Vanessa L.; Emanuel, Peter A.

2004-01-01

Current surface sampling methods for microbial contaminants are designed to sample small areas and utilize culture analysis. The total number of microbes recovered is low because a small area is sampled, making detection of a potential pathogen more difficult. Furthermore, sampling of small areas requires a greater number of samples to be collected, which delays the reporting of results, taxes laboratory resources and staffing, and increases analysis costs. A new biological surface sampling method, the Biological Sampling Kit (BiSKit), designed to sample large areas and to be compatible with testing with a variety of technologies, including PCR and immunoassay, was evaluated and compared to other surface sampling strategies. In experimental room trials, wood laminate and metal surfaces were contaminated by aerosolization of Bacillus atrophaeus spores, a simulant for Bacillus anthracis, into the room, followed by settling of the spores onto the test surfaces. The surfaces were sampled with the BiSKit, a cotton-based swab, and a foam-based swab. Samples were analyzed by culturing, quantitative PCR, and immunological assays. The results showed that the large surface area (1 m2) sampled with the BiSKit resulted in concentrations of B. atrophaeus in samples that were up to 10-fold higher than the concentrations obtained with the other methods tested. A comparison of wet and dry sampling with the BiSKit indicated that dry sampling was more efficient (efficiency, 18.4%) than wet sampling (efficiency, 11.3%). The sensitivities of detection of B. atrophaeus on metal surfaces were 42 ± 5.8 CFU/m2 for wet sampling and 100.5 ± 10.2 CFU/m2 for dry sampling. These results demonstrate that the use of a sampling device capable of sampling larger areas results in higher sensitivity than that obtained with currently available methods and has the advantage of sampling larger areas, thus requiring collection of fewer samples per site. PMID:15574898

Nanoporous Ni with High Surface Area for Potential Hydrogen Storage Application.

PubMed

Zhou, Xiaocao; Zhao, Haibo; Fu, Zhibing; Qu, Jing; Zhong, Minglong; Yang, Xi; Yi, Yong; Wang, Chaoyang

2018-06-01

Nanoporous metals with considerable specific surface areas and hierarchical pore structures exhibit promising applications in the field of hydrogen storage, electrocatalysis, and fuel cells. In this manuscript, a facile method is demonstrated for fabricating nanoporous Ni with a high surface area by using SiO₂ aerogel as a template, i.e., electroless plating of Ni into an SiO₂ aerogel template followed by removal of the template at moderate conditions. The effects of the prepared conditions, including the electroless plating time, temperature of the structure, and the magnetism of nanoporous Ni are investigated in detail. The resultant optimum nanoporous Ni with a special 3D flower-like structure exhibited a high specific surface area of about 120.5 m²/g. The special nanoporous Ni exhibited a promising prospect in the field of hydrogen storage, with a hydrogen capacity of 0.45 wt % on 4.5 MPa at room temperature.

Digital photography and transparency-based methods for measuring wound surface area.

PubMed

Bhedi, Amul; Saxena, Atul K; Gadani, Ravi; Patel, Ritesh

2013-04-01

To compare and determine a credible method of measurement of wound surface area by linear, transparency, and photographic methods for monitoring progress of wound healing accurately and ascertaining whether these methods are significantly different. From April 2005 to December 2006, 40 patients (30 men, 5 women, 5 children) admitted to the surgical ward of Shree Sayaji General Hospital, Baroda, had clean as well as infected wound following trauma, debridement, pressure sore, venous ulcer, and incision and drainage. Wound surface areas were measured by these three methods (linear, transparency, and photographic methods) simultaneously on alternate days. The linear method is statistically and significantly different from transparency and photographic methods (P value <0.05), but there is no significant difference between transparency and photographic methods (P value >0.05). Photographic and transparency methods provided measurements of wound surface area with equivalent result and there was no statistically significant difference between these two methods.

Target surface area effects on hot electron dynamics from high intensity laser–plasma interactions

DOE PAGES

Zulick, C.; Raymond, A.; McKelvey, A.; ...

2016-06-15

Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a K α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Furthermore, Hybrid Vlasov–Fokker–Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.

Reduced Cortical Thickness and Increased Surface Area in Antisocial Personality Disorder

PubMed Central

Jiang, Weixiong; Li, Gang; Liu, Huasheng; Shi, Feng; Wang, Tao; Shen, Celina; Shen, Hui; Hu, Dewen; Wang, Wei; Shen, Dinggang

2016-01-01

Antisocial Personality Disorder (ASPD), one of whose characteristics is high impulsivity, is of great interest in the field of brain structure and function. However, little is known about possible impairments in the cortical anatomy in ASPD, in terms of cortical thickness and surface area, as well as their possible relationship with impulsivity. In this neuroimaging study, we first investigated the changes of cortical thickness and surface area in ASPD patients, in comparison to those of healthy controls, and then performed correlation analyses between these measures and the ability of impulse control. We found that ASPD patients showed thinner cortex while larger surface area in several specific brain regions, i.e., bilateral superior frontal gyrus, orbitofrontal and triangularis, insula cortex, precuneus, middle frontal gyrus, middle temporal gyrus, and left bank of superior temporal sulcus. In addition, we also found that the ability of impulse control was positively correlated with cortical thickness in the superior frontal gyrus, middle frontal gyrus, orbitofrontal cortex, pars triangularis, superior temporal gyrus, and insula cortex. To our knowledge, this study is the first to reveal simultaneous changes in cortical thickness and surface area in ASPD, as well as their relationship with impulsivity. These cortical structural changes may introduce uncontrolled and callous behavioral characteristic in ASPD patients, and these potential biomarkers may be very helpful in understanding the pathomechanism of ASPD. PMID:27600947

Adsorption of water vapour and the specific surface area of arctic zone soils (Spitsbergen)

NASA Astrophysics Data System (ADS)

Cieśla, Jolanta; Sokołowska, Zofia; Witkowska-Walczak, Barbara; Skic, Kamil

2018-01-01

Water vapour/nitrogen adsorption were investigated and calculated the specific surface areas of arctic-zone soil samples (Turbic Cryosols) originating from different micro-relief forms (mud boils, cell forms and sorted circles) and from different depths. For the characterisation of the isotherms obtained for arctic soils, the Brunauer-Emmet-Teller model was then compared with the two other models (Aranovich-Donohue and Guggenheim-Anderson-de Boer) which were developed from Brunauer-Emmet-Teller. Specific surface area was calculated using the Brunauer-Emmet-Teller model at p p0-1 range of 0.05-0.35 for the water vapour desorption and nitrogen adsorption isotherms. The values of total specific surface area were the highest in Cryosols on mud boils, lower on cell forms, and the lowest on sorted circles. Such tendency was observed for the results obtained by both the water vapour and nitrogen adsorption. The differences in the values of specific surface area at two investigated layers were small. High determination coefficients were obtained for relationships between the specific surface areas and contents of clay and silt fraction in Cryosols. No statistically significant correlation between the total carbon amount and the values of specific surface area in Cryosols has been found.

Evaluation of Advanced Reactive Surface Area Estimates for Improved Prediction of Mineral Reaction Rates in Porous Media

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Mitnick, E. H.; Zhang, S.; Voltolini, M.; Yang, L.; Steefel, C. I.; Swift, A.; Cole, D. R.; Sheets, J.; Kneafsey, T. J.; Landrot, G.; Anovitz, L. M.; Mito, S.; Xue, Z.; Ajo Franklin, J. B.; DePaolo, D.

2015-12-01

CO2 sequestration in deep sedimentary formations is a promising means of reducing atmospheric CO2 emissions but the rate and extent of mineral trapping remains difficult to predict. Reactive transport models provide predictions of mineral trapping based on laboratory mineral reaction rates, which have been shown to have large discrepancies with field rates. This, in part, may be due to poor quantification of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area are ad hoc and typically based on grain size, adjusted several orders of magnitude to account for surface roughness and reactivity. This results in orders of magnitude discrepancies in estimated surface areas that directly translate into orders of magnitude discrepancies in model predictions. Additionally, natural systems can be highly heterogeneous and contain abundant nano- and micro-porosity, which can limit connected porosity and access to mineral surfaces. In this study, mineral-specific accessible surface areas are computed for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan). Accessible mineral surface areas are determined from a multi-scale image analysis including X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB. Powder and flow-through column laboratory experiments are performed and the evolution of solutes in the aqueous phase is tracked. Continuum-scale reactive transport models are used to evaluate the impact of reactive surface area on predictions of experimental reaction rates. Evaluated reactive surface areas include geometric and specific surface areas (eg. BET) in addition to their reactive-site weighted counterparts. The most accurate predictions of observed powder mineral dissolution rates were obtained through use of grain-size specific surface areas computed from a BET-based correlation. Effectively, this surface area reflects the grain-fluid contact area, or accessible surface area, in the powder

30 CFR 761.11 - Areas where surface coal mining operations are prohibited or limited.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Areas where surface coal mining operations are....11 Areas where surface coal mining operations are prohibited or limited. You may not conduct surface coal mining operations on the following lands unless you either have valid existing rights, as...

30 CFR 761.11 - Areas where surface coal mining operations are prohibited or limited.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Areas where surface coal mining operations are....11 Areas where surface coal mining operations are prohibited or limited. You may not conduct surface coal mining operations on the following lands unless you either have valid existing rights, as...

30 CFR 761.11 - Areas where surface coal mining operations are prohibited or limited.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Areas where surface coal mining operations are....11 Areas where surface coal mining operations are prohibited or limited. You may not conduct surface coal mining operations on the following lands unless you either have valid existing rights, as...

Active motion on curved surfaces

NASA Astrophysics Data System (ADS)

Castro-Villarreal, Pavel; Sevilla, Francisco J.

2018-05-01

A theoretical analysis of active motion on curved surfaces is presented in terms of a generalization of the telegrapher equation. Such a generalized equation is explicitly derived as the polar approximation of the hierarchy of equations obtained from the corresponding Fokker-Planck equation of active particles diffusing on curved surfaces. The general solution to the generalized telegrapher equation is given for a pulse with vanishing current as initial data. Expressions for the probability density and the mean squared geodesic displacement are given in the limit of weak curvature. As an explicit example of the formulated theory, the case of active motion on the sphere is presented, where oscillations observed in the mean squared geodesic displacement are explained.

A longitudinal study: changes in cortical thickness and surface area during pubertal maturation.

PubMed

Herting, Megan M; Gautam, Prapti; Spielberg, Jeffrey M; Dahl, Ronald E; Sowell, Elizabeth R

2015-01-01

Sex hormones have been shown to contribute to the organization and function of the brain during puberty and adolescence. Moreover, it has been suggested that distinct hormone changes in girls versus boys may contribute to the emergence of sex differences in internalizing and externalizing behavior during adolescence. In the current longitudinal study, the influence of within-subject changes in puberty (physical and hormonal) on cortical thickness and surface area was examined across a 2-year span, while controlling for age. Greater increases in Tanner Stage predicted less superior frontal thinning and decreases in precuneus surface area in both sexes. Significant Tanner Stage and sex interactions were also seen, with less right superior temporal thinning in girls but not boys, as well as greater decreases in the right bank of the superior temporal sulcus surface area in boys compared to girls. In addition, within-subject changes in testosterone over the 2-year follow-up period were found to relate to decreases in middle superior frontal surface area in boys, but increases in surface area in girls. Lastly, larger increases in estradiol in girls predicted greater middle temporal lobe thinning. These results show that within-subject physical and hormonal markers of puberty relate to region and sex-specific changes in cortical development across adolescence.

LANDSAT inventory of surface-mined areas using extendible digital techniques

NASA Technical Reports Server (NTRS)

Anderson, A. T.; Schultz, D. T.; Buchman, N.

1975-01-01

Multispectral LANDSAT imagery was analyzed to provide a rapid and accurate means of identification, classification, and measurement of strip-mined surfaces in Western Maryland. Four band analysis allows distinction of a variety of strip-mine associated classes, but has limited extendibility. A method for surface area measurements of strip mines, which is both geographically and temporally extendible, has been developed using band-ratioed LANDSAT reflectance data. The accuracy of area measurement by this method, averaged over three LANDSAT scenes taken between September 1972 and July 1974, is greater than 93%. Total affected acreage of large (50 hectare/124 acre) mines can be measured to within 1.0%.

Surface modification and electrochemical properties of activated carbons for supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Yang, Dan; Qiu, Wenmei; Xu, Jingcai; Han, Yanbing; Jin, Hongxiao; Jin, Dingfeng; Peng, Xiaoling; Hong, Bo; Li, Ji; Ge, Hongliang; Wang, Xinqing

2015-12-01

Modifications with different acids (HNO3, H2SO4, HCl and HF, respectively) were introduced to treat the activated carbons (ACs) surface. The microstructures and surface chemical properties were discussed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), ASAP, Raman spectra and Fourier transform infrared (FTIR) spectra. The ACs electrode-based supercapacitors were assembled with 6 mol ṡ L-1 KOH electrolyte. The electrochemical properties were studied by galvanostatic charge-discharge and cyclic voltammetry. The results indicated that although the BET surface area of modified ACs decreased, the functional groups were introduced and the ash contents were reduced on the surface of ACs, receiving larger specific capacitance to initial AC. The specific capacitance of ACs modified with HCl, H2SO4, HF and HNO3 increased by 31.4%, 23%, 21% and 11.6%, respectively.

Surface-area-controlled synthesis of porous TiO2 thin films for gas-sensing applications

NASA Astrophysics Data System (ADS)

Park, Jae Young; Kim, Ho-hyoung; Rana, Dolly; Jamwal, Deepika; Katoch, Akash

2017-03-01

Surface-area-controlled porous TiO2 thin films were prepared via a simple sol-gel chemical route, and their gas-sensing properties were thoroughly investigated in the presence of typical oxidizing NO2 gas. The surface area of TiO2 thin films was controlled by developing porous TiO2 networked by means of controlling the TiO2-to-TTIP (titanium isopropoxide, C12H28O4Ti) molar ratio, where TiO2 nanoparticles of size ˜20 nm were used. The sensor’s response was found to depend on the surface area of the TiO2 thin films. The porous TiO2 thin-film sensor with greater surface area was more sensitive than those of TiO2 thin films with lesser surface area. The improved sensing ability was ascribed to the porous network formed within the thin films by TiO2 sol. Our results show that surface area is a key parameter for obtaining superior gas-sensing performance; this provides important guidelines for preparing and using porous thin films for gas-sensing applications.

Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

NASA Astrophysics Data System (ADS)

Zhang, Guoqiang; Li, Zhong; Zheng, Huayan; Hao, Zhiqiang; Wang, Xia; Wang, Jiajun

2016-12-01

Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800 °C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6 m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600 °C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2 m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3 m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600 °C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600 °C to 1200 °C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200 °C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu+ + Cu0) is improved by thermal treatment of AC

Synthesis of hollow NiCo2O4 nanospheres with large specific surface area for asymmetric supercapacitors.

PubMed

Xu, Kaibing; Yang, Jianmao; Hu, Junqing

2018-02-01

Hollow micro-/nanostructured electrode materials with high active surface area are highly desirable for achieving outstanding electrochemical properties. Herein, we report the successful synthesis of hierarchical hollow NiCo 2 O 4 nanospheres with high surface area as electrode materials for supercapacitors. Electrochemical measurements prove that such electrode materials exhibit excellent electrochemical behavior with a specific capacitance reaching 1229 F/g at 1 A/g, remarkable rate performance (∼83.6% retention from 1 to 25 A/g) and good cycling performance (86.3% after 3000 cycles). Furthermore, the asymmetric supercapacitor is fabricated with hollow NiCo 2 O 4 nanospheres electrode and activated carbon (AC) electrode as the positive and negative, respectively. This device exhibits a maximum energy density of 21.5 W h/kg, excellent cycling performance and coulombic efficiency. The results show that hollow NiCo 2 O 4 nanosphere electrode is a promising electrode material for the future application in high performance supercapacitors. Copyright © 2017 Elsevier Inc. All rights reserved.

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

30 CFR 717.15 - Disposal of excess rock and earth materials on surface areas.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Disposal of excess rock and earth materials on surface areas. 717.15 Section 717.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS § 717.15 Disposal of excess rock and earth materials on surface areas. Excess rock and earth...

Determination of the surface area of smectite in water by ethylene oxide chain adsorption.

PubMed

Yuang, Paul-Cheng; Shen, Yun-Hwei

2005-05-15

This study investigates the feasibility of using ethylene oxide (EO) chain adsorption to determine the surface area of smectite in water. Experimental results indicate that high-molecular-weight poly(ethylene oxide) (PEO) should be used to provide reasonable estimations for monolayer capacity of PEO on smectite. The surface areas of smectites in water are calculated from the monolayer capacity of PEO adsorbed on smectite by taking the area per EO unit as 8.05 A(2). The method measures the actual surface area of smectite exposed when dispersed in water, which is important to applications of smectite under aqueous conditions.

Hand surface area estimation formula using 3D anthropometry.

PubMed

Hsu, Yao-Wen; Yu, Chi-Yuang

2010-11-01

Hand surface area is an important reference in occupational hygiene and many other applications. This study derives a formula for the palm surface area (PSA) and hand surface area (HSA) based on three-dimensional (3D) scan data. Two-hundred and seventy subjects, 135 males and 135 females, were recruited for this study. The hand was measured using a high-resolution 3D hand scanner. Precision and accuracy of the scanner is within 0.67%. Both the PSA and HSA were computed using the triangular mesh summation method. A comparison between this study and previous textbook values (such as in the U.K. teaching text and Lund and Browder chart discussed in the article) was performed first to show that previous textbooks overestimated the PSA by 12.0% and HSA by 8.7% (for the male, PSA 8.5% and HSA 4.7%, and for the female, PSA 16.2% and HSA 13.4%). Six 1D measurements were then extracted semiautomatically for use as candidate estimators for the PSA and HSA estimation formula. Stepwise regressions on these six 1D measurements and variable dependency test were performed. Results show that a pair of measurements (hand length and hand breadth) were able to account for 96% of the HSA variance and up to 98% of the PSA variance. A test of the gender-specific formula indicated that gender is not a significant factor in either the PSA or HSA estimation.

The role of advanced reactive surface area characterization in improving predictions of mineral reaction rates

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Zhang, S.; Mitnick, E.; Cole, D. R.; Yang, L.; Anovitz, L. M.; Sheets, J.; Swift, A.; Kneafsey, T. J.; Landrot, G.; Mito, S.; Xue, Z.; Steefel, C. I.; DePaolo, D. J.; Ajo Franklin, J. B.

2014-12-01

Geologic sequestration of CO2 in deep sedimentary formations is a promising means of mitigating carbon emissions from coal-fired power plants but the long-term fate of injected CO2 is challenging to predict. Reactive transport models are used to gain insight over long times but rely on laboratory determined mineral reaction rates that have been difficult to extrapolate to field systems. This, in part, is due to a lack of understanding of mineral reactive surface area. Many models use an arbitrary approximation of reactive surface area, applying orders of magnitude scaling factors to measured BET or geometric surface areas. Recently, a few more sophisticated approaches have used 2D and 3D image analyses to determine mineral-specific reactive surface areas that account for the accessibility of minerals. However, the ability of these advanced surface area estimates to improve predictions of mineral reaction rates has yet to be determined. In this study, we fuse X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB analysis to determine mineral-specific accessible reactive surface areas for a core sample from the Nagaoka pilot CO2 injection site (Japan). This sample is primarily quartz, plagioclase, smectite, K-feldspar, and pyroxene. SEM imaging shows abundant smectite cement and grain coatings that decrease the fluid accessibility of other minerals. However, analysis of FIB-SEM images reveals that smectite nano-pores are well connected such that access to underlying minerals is not occluded by smectite coatings. Mineral-specific accessible surfaces are determined, accounting for the connectivity of the pore space with and without connected smectite nano-pores. The large-scale impact of variations in accessibility and dissolution rates are then determined through continuum scale modeling using grid-cell specific information on accessible surface areas. This approach will be compared with a traditional continuum scale model using mineral abundances and common surface area

Cortical thickness and surface area in neonates at high risk for schizophrenia.

PubMed

Li, Gang; Wang, Li; Shi, Feng; Lyall, Amanda E; Ahn, Mihye; Peng, Ziwen; Zhu, Hongtu; Lin, Weili; Gilmore, John H; Shen, Dinggang

2016-01-01

Schizophrenia is a neurodevelopmental disorder associated with subtle abnormal cortical thickness and cortical surface area. However, it is unclear whether these abnormalities exist in neonates associated with genetic risk for schizophrenia. To this end, this preliminary study was conducted to identify possible abnormalities of cortical thickness and surface area in the high-genetic-risk neonates. Structural magnetic resonance images were acquired from offspring of mothers (N = 21) who had schizophrenia (N = 12) or schizoaffective disorder (N = 9), and also matched healthy neonates of mothers who were free of psychiatric illness (N = 26). Neonatal cortical surfaces were reconstructed and parcellated as regions of interest (ROIs), and cortical thickness for each vertex was computed as the shortest distance between the inner and outer surfaces. Comparisons were made for the average cortical thickness and total surface area in each of 68 cortical ROIs. After false discovery rate (FDR) correction, it was found that the female high-genetic-risk neonates had significantly thinner cortical thickness in the right lateral occipital cortex than the female control neonates. Before FDR correction, the high-genetic-risk neonates had significantly thinner cortex in the left transverse temporal gyrus, left banks of superior temporal sulcus, left lingual gyrus, right paracentral cortex, right posterior cingulate cortex, right temporal pole, and right lateral occipital cortex, compared with the control neonates. Before FDR correction, in comparison with control neonates, male high-risk neonates had significantly thicker cortex in the left frontal pole, left cuneus cortex, and left lateral occipital cortex; while female high-risk neonates had significantly thinner cortex in the bilateral paracentral, bilateral lateral occipital, left transverse temporal, left pars opercularis, right cuneus, and right posterior cingulate cortices. The high-risk neonates also had significantly

A guide to State programs for the reclamation of surface mined areas

USGS Publications Warehouse

Imhoff, Edgar A.; Friz, Thomas O.; LaFevers, James R.

1976-01-01

During 1975 inquiries of agencies in each State and review of State statutes and related administrative codes revealed that 38 States have established programs requiring the reclamation of surface mined lands. Results of analyses of those programs and ancillary data are presented in : (1) A table (matrix) which has been designed for the notation and elaboration of information pertaining to the mined-area reclamation programs of the 50 States; (2) a primer on surface mining activities and related reclamation practices and problems; and (3) a listing of types of non-Federal governmental controls applicable to reclamation. Interpretations of the status and content of State programs suggest that although a common thread runs through State statutory language, administrative requirements vary from State to State in order to meet different natural, economic, social, and political considerations. A general trend is seen in State programs toward the requiring of an integration of landuse planning and mine planning, with increased local governmental involvement.

A CORRELATION BETWEEN RADIATION TOLERANCE AND NUCLEAR SURFACE AREA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iversen, S.

1962-09-22

Sparrow and Miksche (Science, 134:282) determined the dose (r/day) required to produce severe growth inhibition in 23 species of plants and found a linear relationship between log nuclear volume and log dose. The following equations hold for 6 species: log nuclear volume - 4.42 -0.82 log dose and log nuclear volume = 1.66 + 0.66 log (DNA content). If all the nuclear DNA is distributed in two peripheral zones, the equations also hold: 2(log nuclear surface area) - 1.33(log nuclear volume) - 2.21 + 0.88 log(DNA content) and 5.88-- 1.09 log dose. For the 23 species, the equation was obtained:more » 2(log nuclear surface area) = 5.41 -- 0.97 log dose. All the slopes are close to the expected value of 1.00. (D.L.C.)« less

Minimal area surfaces dual to Wilson loops and the Mathieu equation

DOE PAGES

Huang, Changyu; He, Yifei; Kruczenski, Martin

2016-08-11

The AdS/CFT correspondence relates Wilson loops in N=4 SYM to minimal area surfaces in AdS 5 × S 5 space. Recently, a new approach to study minimal area surfaces in AdS 3 c AdS 5 was discussed based on a Schroedinger equation with a periodic potential determined by the Schwarzian derivative of the shape of the Wilson loop. Here we use the Mathieu equation, a standard example of a periodic potential, to obtain a class of Wilson loops such that the area of the dual minimal area surface can be computed analytically in terms of eigenvalues of such equation. Asmore » opposed to previous examples, these minimal surfaces have an umbilical point (where the principal curvatures are equal) and are invariant under λ-deformations. In various limits they reduce to the single and multiple wound circular Wilson loop and to the regular light-like polygons studied by Alday and Maldacena. In this last limit, the periodic potential becomes a series of deep wells each related to a light-like segment. Small corrections are described by a tight-binding approximation. In the circular limit they are well approximated by an expansion developed by A. Dekel. In the particular case of no umbilical points they reduce to a previous solution proposed by J. Toledo. The construction works both in Euclidean and Minkowski signature of AdS 3.« less

Ambient pressure dried tetrapropoxysilane-based silica aerogels with high specific surface area

NASA Astrophysics Data System (ADS)

Parale, Vinayak G.; Han, Wooje; Jung, Hae-Noo-Ree; Lee, Kyu-Yeon; Park, Hyung-Ho

2018-01-01

In the present paper, we report the synthesis of tetrapropoxysilane (TPOS)-based silica aerogels with high surface area and large pore volume. The silica aerogels were prepared by a two-step sol-gel process followed by surface modification via a simple ambient pressure drying approach. In order to minimize drying shrinkage and obtain hydrophobic aerogels, the surface of the alcogels was modified using trichloromethylsilane as a silylating agent. The effect of the sol-gel compositional parameters on the polymerization of aerogels prepared by TPOS, one of the precursors belonging to the Si(OR)4 family, was reported for the first time. The oxalic acid and NH4OH concentrations were adjusted to achieve good-quality aerogels with high surface area, low density, and high transparency. Controlling the hydrolysis and condensation reactions of the TPOS precursor turned out to be the most important factor to determine the pore characteristics of the aerogel. Highly transparent aerogels with high specific surface area (938 m2/g) and low density (0.047 g/cm3) could be obtained using an optimized TPOS/MeOH molar ratio with appropriate concentrations of oxalic acid and NH4OH.

Growth of contact area between rough surfaces under normal stress

NASA Astrophysics Data System (ADS)

Stesky, R. M.; Hannan, S. S.

1987-05-01

The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

The surface activity of purified ocular mucin at the air-liquid interface and interactions with meibomian lipids.

PubMed

Millar, Thomas J; Tragoulias, Sophia T; Anderton, Philip J; Ball, Malcolm S; Miano, Fausto; Dennis, Gary R; Mudgil, Poonam

2006-01-01

Ocular mucins are thought to contribute to the stability of the tear film by reducing surface tension. The purpose of this study was to compare the effect of different mucins and hyaluronic acid (HA) alone and mixed with meibomian lipids on the surface pressure at an air-liquid interface. A Langmuir trough and Wilhelmy balance were used to measure and compare the surface activity of bovine submaxillary gland mucin (BSM), purified BSM, purified bovine ocular mucin and HA, and mixtures of these with meibomian lipids, phosphatidylcholine, and phosphatidylglycerol. Their appearance at the surface of an air-buffer interface was examined using epifluorescence microscopy. Purified ocular mucin had no surface activity even at concentrations that were 100 times more than normally occur in tears. By contrast, commercial BSM caused changes to surface pressure that were concentration dependent. The surface pressure-area profiles showed surface activity with maximum surface pressures of 12.3-22.5 mN/m depending on the concentration. Purified BSM showed no surface activity at low concentrations, whereas higher concentrations reached a maximum surface pressure of 25 mN/m. HA showed no surface activity, at low or high concentrations. Epifluorescence showed that the mucins were located at the air-buffer interface and changed the appearance of lipid films. Purified bovine ocular mucin and HA have no surface activity. However, despite having no surface activity in their own right, ocular mucins are likely to be present at the surface of the tear film, where they cause an increase in surface pressure by causing a compression of the lipids (a reorganization of the lipids) and alter the viscoelastic properties at the surface.

Probing the Active Surface Sites for CO Reduction on Oxide-Derived Copper Electrocatalysts

DOE PAGES

Verdaguer-Casadevall, Arnau; Li, Christina W.; Johansson, Tobias P.; ...

2015-07-30

CO electroreduction activity on oxide-derived Cu (OD-Cu) was found to correlate with metastable surface features that bind CO strongly. OD-Cu electrodes prepared by H 2 reduction of Cu 2O precursors reduce CO to acetate and ethanol with nearly 50% Faradaic efficiency at moderate overpotential. Temperature-programmed desorption of CO on OD-Cu revealed the presence of surface sites with strong CO binding that are distinct from the terraces and stepped sites found on polycrystalline Cu foil. After annealing at 350 °C, the surface-area corrected current density for CO reduction is 44-fold lower and the Faradaic efficiency is less than 5%. These changesmore » are accompanied by a reduction in the proportion of strong CO binding sites. Here, we propose that the active sites for CO reduction on OD-Cu surfaces are strong CO binding sites that are supported by grain boundaries. Uncovering these sites is a first step toward understanding the surface chemistry necessary for efficient CO electroreduction.« less

Impact of Exposure to Pressure of 50 MPa on the Specific Surface Area of Clay

NASA Astrophysics Data System (ADS)

Koszela-Marek, Ewa

2017-12-01

The paper presents results of laboratory tests conducted to determine the impact of pressure of 50 MPa on specific surface area of clay. These tests were carried out in an original, high-pressure test stand. The specific surface area of clay extracted directly from an open pit mine was compared with the specific surface area of the same clay subjected to the pressure of 50 MPa in a high-pressure chamber. The study found that the specific surface area of the clay subjected to the pressure of 50 MPa increased distinctly by over 35 %. The increase in specific surface can be a result of changes in the microstructure of clay particles and microstructural alteration in the soil skeleton, caused by the pressure.

Spatially distributed rockfall activity inferred from talus deposits and corresponding rockwall areas in the Gradenbach catchment (Schober Mountains, Austria)

NASA Astrophysics Data System (ADS)

Götz, Joachim; Buckel, Johannes; Heckmann, Tobias

2013-04-01

The analysis of alpine sediment cascades requires the identification, differentiation and quantification of sediment sources, storages, and transport processes. This study deals with the origin of alpine sediment transfer and relates primary talus deposits to corresponding rockwall source areas within the Gradenbach catchment (Schober Mountains, Austrian Alps). Sediment storage landforms are based on a detailed geomorphological map of the catchment which was generated to analyse the sediment transfer system. Mapping was mainly performed in the field and supplemented by post-mapping analysis using LIDAR data and digital orthophotos. A fundamental part of the mapping procedure was to capture additional landform-based information with respect to morphometry, activity and connectivity. The applied procedure provides a detailed inventory of sediment storage landforms including additional information on surface characteristics, dominant and secondary erosion and deposition processes, process activity and sediment storage coupling. We develop the working hypothesis that the present-day surface area ratio between rockfall talus (area as a proxy for volume, backed by geophysical analysis of selected talus cones) and corresponding rockwall source area is a measure of rockfall activity since deglaciation; large talus cones derived from small rockwall catchments indicate high activity, while low activity can be inferred where rockfall from large rock faces has created only small deposits. The surface area ratio of talus and corresponding rockwalls is analysed using a landform-based and a process-based approach. For the landform-based approach, we designed a GIS procedure which derives the (hydrological) catchment area of the contact lines of talus and rockwall landforms in the geomorphological map. The process-based approach simulates rockfall trajectories from steep (>45°) portions of a DEM generated by a random-walk rockfall model. By back-tracing those trajectories that

Preparation and surface characterization of activated carbons from Euphorbia rigida by chemical activation with ZnCl2, K2CO3, NaOH and H3PO4

NASA Astrophysics Data System (ADS)

Kılıç, Murat; Apaydın-Varol, Esin; Pütün, Ayşe Eren

2012-11-01

Preparation of activated carbons from Euphorbia rigida by chemical activation with different impregnation agents and ratios was studied. ZnCl2, K2CO3, NaOH and H3PO4 were used as chemical activation agents and four impregnation ratios (25-50-75-100%) by mass were applied on biomass. Activation is applied to impregnated biomass samples at 700 °C under sweeping gas in a fixed bed reactor. For determination of chemical and physical properties of the obtained activated carbons; elemental analysis was applied to determine the elemental composition (C, H, N, O) and FT-IR spectra was used to analyze the functional groups. BET equation was used to calculate the surface areas of activated carbons. For understanding the changes in the surface structure, activated carbons were conducted to Scanning Electron Microscopy (SEM). Maximum BET surface area (2613 m2/g) was reached with 75% K2CO3 impregnated biomass sample. Experimental results showed that impregnation types and ratios have a significant effect on the pore structure of activated carbon and E. rigida seems to be an alternative precursor for commercial activated carbon production.

Direct Push supported geotechnical and hydrogeological characterisation of an active sinkhole area

NASA Astrophysics Data System (ADS)

Tippelt, Thomas; Vienken, Thomas; Kirsch, Reinhard; Dietrich, Peter; Werban, Ulrike

2017-04-01

Sinkholes represent a natural geologic hazard in areas where soluble layers are present in the subsurface. A detailed knowledge of the composition of the subsurface and its hydrogeological and geotechnical properties is essential for the understanding of sinkhole formation and propagation. This serves as base for risk evaluation and the development of an early warning system. However, site models often depend on data from drillings and surface geophysical surveys that in many cases cannot resolve the spatial distribution of relevant hydrogeological and geotechnical parameters sufficiently. Therefore, an active sinkhole area in Münsterdorf, Northern Germany, was investigated in detail using Direct Push technology, a minimally invasive sounding method. The obtained vertical high-resolution profiles of geotechnical and hydrogeological characteristics, in combination with Direct Push based sampling and surface geophysical measurements lead to a strong improvement of the geologic site model. The conceptual site model regarding sinkhole formation and propagation will then be tested based on the gathered data and, if necessary, adapted accordingly.

Effect of specific surface area of MWCNTS on surface roughness and delamination in drilling Epoxy/Glass Fabric Composite

NASA Astrophysics Data System (ADS)

Ponnuvel, S.; Ananth, M. Prem

2018-03-01

In this study the effect of specific surface area of the MWCNTs on the drilled hole qualities was investigated. Epoxy araldite LY556 with hardener HY951 and E-glass coarse plain weave fabric are used for the fabrication of reference material (specimen A). Multi-WalledCarbon Nanotubes (MWCNTs) with diameters <8 nm and 20–30 nm are used for the fabrication of study materials, namely specimen B and specimen C respectively. In specimen B the epoxy resin was filled with MWCNTs having a specific surface area >500 m2 g‑1. MWCNTs in specimen C had a specific surface area >110 m2 g‑1. Drilling experiments were conducted on all the three specimens. Two dimensional delamination factor and the surface roughness of the inner wall of the drilled holes were investigated using Grey Relational Analysis (GRA) and Analysis of variance (ANOVA). Two dimensional delamination factor showed better performance from specimen B and specimen C in comparison with specimen A suggesting improvement in the bonding between epoxy and the glass fiber in the presence of MWCNTs. Similar observations were made for surface roughness of the inner wall of the drilled holes at 1250 rpm. Whereas the presence of MWCNTs (Specimen B and specimen C) produced poor surface finish at 500 rpm in comparison with specimen A. Variations in the hole quality characteristics between specimen B and specimen C was marginal with better observations in specimen C.

Planar spatial correlations, anisotropy, and specific surface area of stationary random porous media

NASA Astrophysics Data System (ADS)

Berryman, James G.

1998-02-01

An earlier result of the author showed that an anisotropic spatial correlation function of a random porous medium could be used to compute the specific surface area when it is stationary as well as anisotropic by first performing a three-dimensional radial average and then taking the first derivative with respect to lag at the origin. This result generalized the earlier result for isotropic porous media of Debye et al. [J. Appl. Phys. 28, 679 (1957)]. The present article provides more detailed information about the use of spatial correlation functions for anisotropic porous media and in particular shows that, for stationary anisotropic media, the specific surface area can be related to the derivative of the two-dimensional radial average of the correlation function measured from cross sections taken through the anisotropic medium. The main concept is first illustrated using a simple pedagogical example for an anisotropic distribution of spherical voids. Then, a general derivation of formulas relating the derivative of the planar correlation functions to surface integrals is presented. When the surface normal is uniformly distributed (as is the case for any distribution of spherical voids), our formulas can be used to relate a specific surface area to easily measurable quantities from any single cross section. When the surface normal is not distributed uniformly (as would be the case for an oriented distribution of ellipsoidal voids), our results show how to obtain valid estimates of specific surface area by averaging measurements on three orthogonal cross sections. One important general observation for porous media is that the surface area from nearly flat cracks may be underestimated from measurements on orthogonal cross sections if any of the cross sections happen to lie in the plane of the cracks. This result is illustrated by taking the very small aspect ratio (penny-shaped crack) limit of an oblate spheroid, but holds for other types of flat surfaces as well.

Planar spatial correlations, anisotropy, and specific surface area of stationary random porous media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berryman, J.G.

1998-02-01

An earlier result of the author showed that an anisotropic spatial correlation function of a random porous medium could be used to compute the specific surface area when it is stationary as well as anisotropic by first performing a three-dimensional radial average and then taking the first derivative with respect to lag at the origin. This result generalized the earlier result for isotropic porous media of Debye {ital et al.} [J. Appl. Phys. {bold 28}, 679 (1957)]. The present article provides more detailed information about the use of spatial correlation functions for anisotropic porous media and in particular shows that,more » for stationary anisotropic media, the specific surface area can be related to the derivative of the two-dimensional radial average of the correlation function measured from cross sections taken through the anisotropic medium. The main concept is first illustrated using a simple pedagogical example for an anisotropic distribution of spherical voids. Then, a general derivation of formulas relating the derivative of the planar correlation functions to surface integrals is presented. When the surface normal is uniformly distributed (as is the case for any distribution of spherical voids), our formulas can be used to relate a specific surface area to easily measurable quantities from any single cross section. When the surface normal is not distributed uniformly (as would be the case for an oriented distribution of ellipsoidal voids), our results show how to obtain valid estimates of specific surface area by averaging measurements on three orthogonal cross sections. One important general observation for porous media is that the surface area from nearly flat cracks may be underestimated from measurements on orthogonal cross sections if any of the cross sections happen to lie in the plane of the cracks. This result is illustrated by taking the very small aspect ratio (penny-shaped crack) limit of an oblate spheroid, but holds for other types of

Graphene oxide: surface activity and two-dimensional assembly.

PubMed

Kim, Franklin; Cote, Laura J; Huang, Jiaxing

2010-05-04

Graphene oxide (GO) is a promising precursor for preparing graphene-based composites and electronics applications. Like graphene, GO is essentially one-atom thick but can be as wide as tens of micrometers, resulting in a unique type of material building block, characterized by two very different length scales. Due to this highly anisotropic structure, the collective material properties are highly dependent on how these sheets are assembled. Therefore, understanding and controlling the assembly behavior of GO has become an important subject of research. In this Research News article the surface activity of GO and how it can be employed to create two-dimensional assemblies over large areas is discussed.

Measuring the specific surface area of natural and manmade glasses: effects of formation process, morphology, and particle size

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papelis, Charalambos; Um, Wooyong; Russel, Charles E.

2003-03-28

The specific surface area of natural and manmade solid materials is a key parameter controlling important interfacial processes in natural environments and engineered systems, including dissolution reactions and sorption processes at solid-fluid interfaces. To improve our ability to quantify the release of trace elements trapped in natural glasses, the release of hazardous compounds trapped in manmade glasses, or the release of radionuclides from nuclear melt glass, we measured the specific surface area of natural and manmade glasses as a function of particle size, morphology, and composition. Volcanic ash, volcanic tuff, tektites, obsidian glass, and in situ vitrified rock were analyzed.more » Specific surface area estimates were obtained using krypton as gas adsorbent and the BET model. The range of surface areas measured exceeded three orders of magnitude. A tektite sample had the highest surface area (1.65 m2/g), while one of the samples of in situ vitrified rock had the lowest surf ace area (0.0016 m2/g). The specific surface area of the samples was a function of particle size, decreasing with increasing particle size. Different types of materials, however, showed variable dependence on particle size, and could be assigned to one of three distinct groups: (1) samples with low surface area dependence on particle size and surface areas approximately two orders of magnitude higher than the surface area of smooth spheres of equivalent size. The specific surface area of these materials was attributed mostly to internal porosity and surface roughness. (2) samples that showed a trend of decreasing surface area dependence on particle size as the particle size increased. The minimum specific surface area of these materials was between 0.1 and 0.01 m2/g and was also attributed to internal porosity and surface roughness. (3) samples whose surface area showed a monotonic decrease with increasing particle size, never reaching an ultimate surface area limit within the

The impact of surface area, volume, curvature, and Lennard-Jones potential to solvation modeling.

PubMed

Nguyen, Duc D; Wei, Guo-Wei

2017-01-05

This article explores the impact of surface area, volume, curvature, and Lennard-Jones (LJ) potential on solvation free energy predictions. Rigidity surfaces are utilized to generate robust analytical expressions for maximum, minimum, mean, and Gaussian curvatures of solvent-solute interfaces, and define a generalized Poisson-Boltzmann (GPB) equation with a smooth dielectric profile. Extensive correlation analysis is performed to examine the linear dependence of surface area, surface enclosed volume, maximum curvature, minimum curvature, mean curvature, and Gaussian curvature for solvation modeling. It is found that surface area and surfaces enclosed volumes are highly correlated to each other's, and poorly correlated to various curvatures for six test sets of molecules. Different curvatures are weakly correlated to each other for six test sets of molecules, but are strongly correlated to each other within each test set of molecules. Based on correlation analysis, we construct twenty six nontrivial nonpolar solvation models. Our numerical results reveal that the LJ potential plays a vital role in nonpolar solvation modeling, especially for molecules involving strong van der Waals interactions. It is found that curvatures are at least as important as surface area or surface enclosed volume in nonpolar solvation modeling. In conjugation with the GPB model, various curvature-based nonpolar solvation models are shown to offer some of the best solvation free energy predictions for a wide range of test sets. For example, root mean square errors from a model constituting surface area, volume, mean curvature, and LJ potential are less than 0.42 kcal/mol for all test sets. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Estimating 3-dimensional colony surface area of field corals

EPA Science Inventory

Colony surface area is a critical descriptor for biological and physical attributes of reef-building (scleractinian, stony) corals. The three-dimensional (3D) size and structure of corals are directly related to many ecosystem values and functions. Most methods to estimate colony...

Synthesis, characterization, antibacterial activity in dark and in vitro cytocompatibility of Ag-incorporated TiO2 microspheres with high specific surface area.

PubMed

Weng, Shengxin; Zhao, Xu; Liu, Guomin; Guan, Yuefeng; Wu, Fanglong; Luo, Yungang

2018-04-23

Postoperative infection associated with medical implants is a devastating complication of orthopedic surgery. Considering the difficulties for the diagnosis and treatment of infection, coating the implant material with antibacterial substances is a promising protocol by which to avoid such an adverse reaction. Nanoparticles (NPs) constructed of anatase microspheres, one form of titanium dioxide (TiO 2 ), with a high specific surface area are fabricated in this study in a facile one-step process using homogeneous precipitation at 90 °C under atmospheric pressure using titanium sulfate (Ti[SO 4 ] 2 ) and urea as the titanium source and precipitant, respectively. The molar ratio of silver (Ag) to TiO 2 can be changed by varying the amount of silver nitrate (AgNO 3 ). The high specific surface area of the TiO 2 microspheres combined with Ag particles (Ag/TiO 2 ) exhibit excellent antibacterial properties against both Staphylococcus aureus and Escherichia coli. In addition, the Ag/TiO 2 material in this work possesses satisfactory biological performance on MC3T3-E1 cells. The high specific surface area of Ag/TiO 2 together with good antibacterial properties and cytocompatibility provide promising applications in dentistry, orthopedics, and other fields of medicine that use biomedical devices.

Estimation of surface area concentration of workplace incidental nanoparticles based on number and mass concentrations

NASA Astrophysics Data System (ADS)

Park, J. Y.; Ramachandran, G.; Raynor, P. C.; Kim, S. W.

2011-10-01

Surface area was estimated by three different methods using number and/or mass concentrations obtained from either two or three instruments that are commonly used in the field. The estimated surface area concentrations were compared with reference surface area concentrations (SAREF) calculated from the particle size distributions obtained from a scanning mobility particle sizer and an optical particle counter (OPC). The first estimation method (SAPSD) used particle size distribution measured by a condensation particle counter (CPC) and an OPC. The second method (SAINV1) used an inversion routine based on PM1.0, PM2.5, and number concentrations to reconstruct assumed lognormal size distributions by minimizing the difference between measurements and calculated values. The third method (SAINV2) utilized a simpler inversion method that used PM1.0 and number concentrations to construct a lognormal size distribution with an assumed value of geometric standard deviation. All estimated surface area concentrations were calculated from the reconstructed size distributions. These methods were evaluated using particle measurements obtained in a restaurant, an aluminum die-casting factory, and a diesel engine laboratory. SAPSD was 0.7-1.8 times higher and SAINV1 and SAINV2 were 2.2-8 times higher than SAREF in the restaurant and diesel engine laboratory. In the die casting facility, all estimated surface area concentrations were lower than SAREF. However, the estimated surface area concentration using all three methods had qualitatively similar exposure trends and rankings to those using SAREF within a workplace. This study suggests that surface area concentration estimation based on particle size distribution (SAPSD) is a more accurate and convenient method to estimate surface area concentrations than estimation methods using inversion routines and may be feasible to use for classifying exposure groups and identifying exposure trends.

Surface water polycyclic aromatic hydrocarbons (PAH) in urban areas of Nanjing, China.

PubMed

Wang, Chunhui; Zhou, Shenglu; Wu, Shaohua; Song, Jing; Shi, Yaxing; Li, Baojie; Chen, Hao

2017-10-01

The concentration, sources and environmental risks of polycyclic aromatic hydrocarbons (PAHs) in surface water in urban areas of Nanjing were investigated. The range of ∑ 16 PAHs concentration is between 4,076 and 29,455 ng/L, with a mean of 17,212 ng/L. The composition of PAHs indicated that 2- and 3-ring PAHs have the highest proportion in all PAHs, while the 5- and 6-ring PAHs were the least in proportion. By diagnostic ratio analysis, combustion and petroleum were a mixture input that contributed to the water PAH in urban areas of Nanjing. Positive matrix factorization quantitatively identified four factors, including coke oven, coal combustion, oil source, and vehicle emission, as the main sources. Toxic equivalency factors of BaP (BaP eq ) evaluate the environmental risks of PAHs and indicate the PAH concentration in surface water in urban areas of Nanjing had been polluted and might cause potential environmental risks. Therefore, the PAH contamination in surface water in urban areas of Nanjing should draw considerable attention.

Method of forming macro-structured high surface area transparent conductive oxide electrodes

DOEpatents

Forman, Arnold J.; Chen, Zhebo; Jaramillo, Thomas F.

2016-01-05

A method of forming a high surface area transparent conducting electrode is provided that includes depositing a transparent conducting thin film on a conductive substrate, where the transparent conducting thin film includes transparent conductive particles and a solution-based transparent conducting adhesive layer which serves to coat and bind together the transparent conducting particles, and heat treating the transparent conducting adhesion layer on the conductive substrate, where an increased surface area transparent conducting electrode is formed.

Cd(II) removal on surface-modified activated carbon: equilibrium, kinetics and mechanism.

PubMed

Liang, Jianjun; Liu, Meiling; Zhang, Yufei

2016-10-01

Commercial pulverous activated carbon (AC-0) was modified through two steps: oxidize AC-0 acid firstly, impregnate it with iron using ferric chloride secondly. Orthogonal experiment was conducted then to prepare modified activated carbon with high Cd(II) adsorption capacity (ACNF). Batch adsorption experiments were undertaken to determine the adsorption characteristics of Cd(II) from aqueous solution onto AC-0 and ACNF and the effect of pH, contact time and initial Cd(II) concentration. The results indicate that: the adsorption behavior of Cd(II) on ACNF can be well fitted with Langmuir model, and the maximum adsorption capacity of ACNF was 2.3 times higher than that of AC-0, supporting a monolayer coverage of Cd(II) on the surface. The kinetics of the adsorption process can be described by pseudo-second-order rate equation very well, and the adsorption capacity increased from 0.810 mg/g to 0.960 mg/g after modification. Compared with AC-0, the kinetic parameters of ACNF showed a higher adsorption rate through the aqueous solution to the solid surface and a lower intraparticle diffusion rate. Surface modification resulted in a lower Brunauer-Emmett-Teller (BET) surface area and pore size because of the collapse and blockage of pores, according to the X-ray diffraction (XRD) analysis, while the total number of surface oxygen acid groups increased, and this was supposed to contribute to the enhanced adsorption capacity of modified activated carbon.

Green Bank Telescope active surface system

NASA Astrophysics Data System (ADS)

Lacasse, Richard J.

1998-05-01

During the design phase of the Green Bank Telescope (GBT), various means of providing an accurate surface on a large aperture paraboloid, were considered. Automated jacks supporting the primary reflector were selected as the appropriate technology since they promised greater performance and potentially lower costs than a homologous or carbon fiber design, and had certain advantages over an active secondary. The design of the active surface has presented many challenges. Since the actuators are mounted on a tipping structure, it was required that they support a significant side-load. Such devices were not readily available commercially so they had to be developed. Additional actuator requirements include low backlash, repeatable positioning, and an operational life of at least 230 years. Similarly, no control system capable of controlling the 2209 actuators was commercially available. Again a prime requirement was reliability. Maintaining was also a very important consideration. The system architecture is tree-like. An active surface 'master-computer' controls interaction with the telescope control system, and controls ancillary equipment such as power supplies and temperature monitors. Two slave computers interface with the master- computer, and each closes approximately 1100 position loops. For simplicity, the servo is an 'on/off' type, yet achieves a positioning resolution of 25 microns. Each slave computer interfaces with 4 VME I/O cards, which in turn communicate with 140 control modules. The control modules read out the positions of the actuators every 0.1 sec and control the actuators' DC motors. Initial control of the active surface will be based on an elevation dependant structural model. Later, the model will be improved by holographic observations.Surface accuracy will be improved further by using laser ranging system which will actively measure the surface figure. Several tests have been conducted to assure that the system will perform as desired when

Heavy metal contamination of surface soil in electronic waste dismantling area: site investigation and source-apportionment analysis.

PubMed

Jinhui Li; Huabo Duan; Pixing Shi

2011-07-01

The dismantling and disposal of electronic waste (e-waste) in developing countries is causing increasing concern because of its impacts on the environment and risks to human health. Heavy-metal concentrations in the surface soils of Guiyu (Guangdong Province, China) were monitored to determine the status of heavy-metal contamination on e-waste dismantling area with a more than 20 years history. Two metalloids and nine metals were selected for investigation. This paper also attempts to compare the data among a variety of e-waste dismantling areas, after reviewing a number of heavy-metal contamination-related studies in such areas in China over the past decade. In addition, source apportionment of heavy metal in the surface soil of these areas has been analysed. Both the MSW open-burning sites probably contained invaluable e-waste and abandoned sites formerly involved in informal recycling activities are the new sources of soil-based environmental pollution in Guiyu. Although printed circuit board waste is thought to be the main source of heavy-metal emissions during e-waste processing, requirement is necessary to soundly manage the plastic separated from e-waste, which mostly contains heavy metals and other toxic substances.

Optimization of Thick, Large Area YBCO Film Growth Through Response Surface Methods

NASA Astrophysics Data System (ADS)

Porzio, J.; Mahoney, C. H.; Sullivan, M. C.

2014-03-01

We present our work on the optimization of thick, large area YB2C3O7-δ (YBCO) film growth through response surface methods. Thick, large area films have commercial uses and have recently been used in dramatic demonstrations of levitation and suspension. Our films are grown via pulsed laser deposition and we have optimized growth parameters via response surface methods. Response surface methods is a statistical tool to optimize selected quantities with respect to a set of variables. We optimized our YBCO films' critical temperatures, thicknesses, and structures with respect to three PLD growth parameters: deposition temperature, laser energy, and deposition pressure. We will present an overview of YBCO growth via pulsed laser deposition, the statistical theory behind response surface methods, and the application of response surface methods to pulsed laser deposition growth of YBCO. Results from the experiment will be presented in a discussion of the optimized film quality. Supported by NFS grant DMR-1305637

30 CFR 57.17001 - Illumination of surface working areas.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Illumination of surface working areas. 57.17001 Section 57.17001 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES...

Increasing biochar surface area: Optimization of ball milling parameters

USDA-ARS?s Scientific Manuscript database

Biochar produced from corn stover is a renewable, plentiful source of carbon that is a potential substitute for carbon black as rubber composite filler and also as binder/filter media for water or beverage purification applications. However, to be successful in these applications, the surface area o...

Trophic structure and microbial activity in a spawning area of Engraulis encrasicolus

NASA Astrophysics Data System (ADS)

Zaccone, R.; Azzaro, M.; Azzaro, F.; Caruso, G.; Caroppo, C.; Decembrini, F.; Diociaiuti, T.; Fonda Umani, S.; Leonardi, M.; Maimone, G.; Monticelli, L. S.; Paranhos, R.; Placenti, F.; Cuttitta, A.; Patti, B.; La Ferla, R.

2018-07-01

The abundance, biomass and size-structure of planktonic populations, and the microbial metabolic processes were studied in the Sicily Channel, one of the most important spawning areas in the Mediterranean for anchovy (Engraulis encrasicolus), a pelagic species of commercial interest. Results showed that prokaryotes contribute for the 83% of total carbon biomass. Microphytoplankton abundances and biomasses were dominated by autotrophic nanoflagellates and dinoflagellates (36 identified species) and contribute 11% of total biomass. The microzooplanktonic biomass showed its maximum at the surface or subsurface and its contribution was low (4%). In agreement with the general oligotrophy of the investigated area, the study highlights the prevalence of pico-sized fractions within the whole phytoplankton biomass expressed as chlorophyll content, suggesting the importance of picophytoplankton in sustaining the microbial food web. At the same time, the levels of microbial hydrolytic activities are related to productive processes recycling the organic matter and releasing nutrients (P and N), indicating also an active functioning of ecosystem at low trophic levels. Autotrophic production exceeded oxidation by respiration; at the same time, the co-variation of prokaryotic activities and eggs distribution with temperature in summer was observed. The results obtained confirmed that the area acted as a nursery for small fish and both autotrophic and heterotrophic processes supported by microorganisms were in synergy.

M-shaped grating by nanoimprinting: a replicable, large-area, highly active plasmonic surface-enhanced Raman scattering substrate with nanogaps.

PubMed

Zhu, Zhendong; Bai, Benfeng; Duan, Huigao; Zhang, Haosu; Zhang, Mingqian; You, Oubo; Li, Qunqing; Tan, Qiaofeng; Wang, Jia; Fan, Shoushan; Jin, Guofan

2014-04-24

Plasmonic nanostructures separated by nanogaps enable strong electromagnetic-field confinement on the nanoscale for enhancing light-matter interactions, which are in great demand in many applications such as surface-enhanced Raman scattering (SERS). A simple M-shaped nanograting with narrow V-shaped grooves is proposed. Both theoretical and experimental studies reveal that the electromagnetic field on the surface of the M grating can be pronouncedly enhanced over that of a grating without such grooves, due to field localization in the nanogaps formed by the narrow V grooves. A technique based on room-temperature nanoimprinting lithography and anisotropic reactive-ion etching is developed to fabricate this device, which is cost-effective, reliable, and suitable for fabricating large-area nanostructures. As a demonstration of the potential application of this device, the M grating is used as a SERS substrate for probing Rhodamine 6G molecules. Experimentally, an average SERS enhancement factor as high as 5×10⁸ has been achieved, which verifies the greatly enhanced light-matter interaction on the surface of the M grating over that of traditional SERS surfaces. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular effective coverage surface area of optical clearing agents for predicting optical clearing potential

NASA Astrophysics Data System (ADS)

Feng, Wei; Ma, Ning; Zhu, Dan

2015-03-01

The improvement of methods for optical clearing agent prediction exerts an important impact on tissue optical clearing technique. The molecular dynamic simulation is one of the most convincing and simplest approaches to predict the optical clearing potential of agents by analyzing the hydrogen bonds, hydrogen bridges and hydrogen bridges type forming between agents and collagen. However, the above analysis methods still suffer from some problem such as analysis of cyclic molecule by reason of molecular conformation. In this study, a molecular effective coverage surface area based on the molecular dynamic simulation was proposed to predict the potential of optical clearing agents. Several typical cyclic molecules, fructose, glucose and chain molecules, sorbitol, xylitol were analyzed by calculating their molecular effective coverage surface area, hydrogen bonds, hydrogen bridges and hydrogen bridges type, respectively. In order to verify this analysis methods, in vitro skin samples optical clearing efficacy were measured after 25 min immersing in the solutions, fructose, glucose, sorbitol and xylitol at concentration of 3.5 M using 1951 USAF resolution test target. The experimental results show accordance with prediction of molecular effective coverage surface area. Further to compare molecular effective coverage surface area with other parameters, it can show that molecular effective coverage surface area has a better performance in predicting OCP of agents.

Facile synthesis of high surface area molybdenum nitride and carbide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Aaron; Serov, Alexey; Artyushkova, Kateryna

2015-08-15

The synthesis of high surface area γ-Mo{sub 2}N and α-Mo{sub 2}C is reported (116 and 120 m{sup 2}/g) without the temperature programmed reduction of MoO{sub 3}. γ-Mo{sub 2}N was prepared in an NH{sub 3}-free synthesis using forming gas (7 at% H{sub 2}, N{sub 2}-balance) as the reactive atmosphere. Three precursors were studied ((NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}·4H{sub 2}O, (NH{sub 4}){sub 2} Mg(MoO{sub 4}){sub 2}, and MgMoO{sub 4}) along with the sacrificial support method (SSM) as a means of reducing the particle size of Mo{sub 2}N and Mo{sub 2}C. In situ X-ray diffraction (XRD) studies were carried out to identify reactionmore » intermediates, the temperature at which various intermediates form, and the average domain size of the Mo{sub 2}N products. Materials were synthesized in bulk and further characterized by XRD, HRTEM, XPS, and BET. - Highlights: • Facile synthesis of γ-Mo2N and α-Mo2C with surface area exceeding 100 m{sup 2}/g. • Sacrificial support method was used to achieve these high surface areas. • Materials can serve as catalysts or supports in (electro)chemical processes.« less

City landscape changes effects on land surface temperature in Bucharest metropolitan area

NASA Astrophysics Data System (ADS)

Savastru, Dan M.; Zoran, Maria A.; Savastru, Roxana S.; Dida, Adrian I.

2017-10-01

This study investigated the influences of city land cover changes and extreme climate events on land surface temperature in relationship with several biophysical variables in Bucharest metropolitan area of Romania through satellite and in-situ monitoring data. Remote sensing data from IKONOS, Landsat TM/ETM+ and time series MODIS Terra/Aqua and NOAA AVHRR sensors have been used to assess urban land cover- temperature interactions over 2000 - 2016 period. Time series Thermal InfraRed (TIR) satellite remote sensing data in synergy with meteorological data (air temperatureAT, precipitations, wind, solar radiation, etc.) were applied mainly for analyzing land surface temperature (LST) pattern and its relationship with surface landscape characteristics, assessing urban heat island (UHI), and relating urban land cover temperatures (LST). The land surface temperature, a key parameter for urban thermal characteristics analysis, was also analyzed in relation with the Normalized Difference Vegetation Index (NDVI) at city level. Results show that in the metropolitan area ratio of impervious surface in Bucharest increased significantly during investigated period, the intensity of urban heat island and heat wave events being most significant. The correlation analyses revealed that, at the pixel-scale, LST and AT possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at metropolitan scale respectively. The NDVI was significantly correlated with precipitation. The spatial average air temperatures in urban test areas rise with the expansion of the urban size.

Occurrence of Surface Active Agents in the Environment

PubMed Central

Olkowska, Ewa; Ruman, Marek; Polkowska, Żaneta

2014-01-01

Due to the specific structure of surfactants molecules they are applied in different areas of human activity (industry, household). After using and discharging from wastewater treatment plants as effluent stream, surface active agents (SAAs) are emitted to various elements of the environment (atmosphere, waters, and solid phases), where they can undergo numerous physic-chemical processes (e.g., sorption, degradation) and freely migrate. Additionally, SAAs present in the environment can be accumulated in living organisms (bioaccumulation), what can have a negative effect on biotic elements of ecosystems (e.g., toxicity, disturbance of endocrine equilibrium). They also cause increaseing solubility of organic pollutants in aqueous phase, their migration, and accumulation in different environmental compartments. Moreover, surfactants found in aerosols can affect formation and development of clouds, which is associated with cooling effect in the atmosphere and climate changes. The environmental fate of SAAs is still unknown and recognition of this problem will contribute to protection of living organisms as well as preservation of quality and balance of various ecosystems. This work contains basic information about surfactants and overview of pollution of different ecosystems caused by them (their classification and properties, areas of use, their presence, and behavior in the environment). PMID:24527257

Prothrombin activation on the activated platelet surface optimizes expression of procoagulant activity

PubMed Central

Wood, Jeremy P.; Silveira, Jay R.; Maille, Nicole M.; Haynes, Laura M.

2011-01-01

Effective hemostasis relies on the timely formation of α-thrombin via prothrombinase, a Ca2+-dependent complex of factors Va and Xa assembled on the activated platelet surface, which cleaves prothrombin at Arg271 and Arg320. Whereas initial cleavage at Arg271 generates the inactive intermediate prethrombin-2, initial cleavage at Arg320 generates the enzymatically active intermediate meizothrombin. To determine which of these intermediates is formed when prothrombin is processed on the activated platelet surface, the cleavage of prothrombin, and prothrombin mutants lacking either one of the cleavage sites, was monitored on the surface of either thrombin- or collagen-activated platelets. Regardless of the agonist used, prothrombin was initially cleaved at Arg271 generating prethrombin-2, with α-thrombin formation quickly after via cleavage at Arg320. The pathway used was independent of the source of factor Va (plasma- or platelet-derived) and was unaffected by soluble components of the platelet releasate. When both cleavage sites are presented within the same substrate molecule, Arg271 effectively competes against Arg320 (with an apparent IC50 = 0.3μM), such that more than 90% to 95% of the initial cleavage occurs at Arg271. We hypothesize that use of the prethrombin-2 pathway serves to optimize the procoagulant activity expressed by activated platelets, by limiting the anticoagulant functions of the alternate intermediate, meizothrombin. PMID:21131592

Prothrombin activation on the activated platelet surface optimizes expression of procoagulant activity.

PubMed

Wood, Jeremy P; Silveira, Jay R; Maille, Nicole M; Haynes, Laura M; Tracy, Paula B

2011-02-03

Effective hemostasis relies on the timely formation of α-thrombin via prothrombinase, a Ca(2+)-dependent complex of factors Va and Xa assembled on the activated platelet surface, which cleaves prothrombin at Arg271 and Arg320. Whereas initial cleavage at Arg271 generates the inactive intermediate prethrombin-2, initial cleavage at Arg320 generates the enzymatically active intermediate meizothrombin. To determine which of these intermediates is formed when prothrombin is processed on the activated platelet surface, the cleavage of prothrombin, and prothrombin mutants lacking either one of the cleavage sites, was monitored on the surface of either thrombin- or collagen-activated platelets. Regardless of the agonist used, prothrombin was initially cleaved at Arg271 generating prethrombin-2, with α-thrombin formation quickly after via cleavage at Arg320. The pathway used was independent of the source of factor Va (plasma- or platelet-derived) and was unaffected by soluble components of the platelet releasate. When both cleavage sites are presented within the same substrate molecule, Arg271 effectively competes against Arg320 (with an apparent IC(50) = 0.3μM), such that more than 90% to 95% of the initial cleavage occurs at Arg271. We hypothesize that use of the prethrombin-2 pathway serves to optimize the procoagulant activity expressed by activated platelets, by limiting the anticoagulant functions of the alternate intermediate, meizothrombin.

Fibroblast adhesion and activation onto micro-machined titanium surfaces.

PubMed

Guillem-Marti, J; Delgado, L; Godoy-Gallardo, M; Pegueroles, M; Herrero, M; Gil, F J

2013-07-01

Surface modifications performed at the neck of dental implants, in the manner of micro-grooved surfaces, can reduce fibrous tissue encapsulation and prevent bacterial colonization, thereby improving fibrointegration and the formation of a biological seal. However, the applied procedures are technically complex and/or time consuming methods. The aim of this study was to analyse the fibroblast behaviour on modified titanium surfaces obtained, applying a simple and low-cost method. An array of titanium surfaces was obtained using a commercial computerized numerical control lathe, modifying the feed rate and the cutting depth. To elucidate the potential ability of the generated surfaces to activate connective tissue cells, a thorough gene (by real time - qPCR) and protein (by western blot or zymography) expression and cellular response characterization (cell morphology, cell adhesion and cell activation by secreting extracellular matrix (ECM) components and their enzyme regulators) was performed. Micro-grooved surfaces have statistically significant differences in the groove's width (approximately 10, 50 and 100 μm) depending on the applied advancing fixed speed. Field emission scanning electron microscopy images showed that fibroblasts oriented along the generated grooves, but they were only entirely accommodated on the wider grooves (≥50 μm). Micro-grooved surfaces exhibited an earlier cell attachment and activation, as seen by collagen Iα1 and fibronectin deposition and activation of ECM remodelling enzymes, compared with the other surfaces. However, fibroblasts could remain in an activated state on narrower surfaces (<50 μm) at later stages. The use of micro-grooved surfaces could improve implant integration at the gingival site with respect to polished surfaces. Micro-grooved surfaces enhance early fibroblast adhesion and activation, which could be critical for the formation of a biological seal and finally promote tissue integration. Surfaces with wider

Immobilization of Active Bacteriophages on Polyhydroxyalkanoate Surfaces.

PubMed

Wang, Chanchan; Sauvageau, Dominic; Elias, Anastasia

2016-01-20

A rapid, efficient technique for the attachment of bacteriophages (phages) onto polyhydroxyalkanoate (PHA) surfaces has been developed and compared to three reported methods for phage immobilization. Polymer surfaces were modified to facilitate phage attachment using (1) plasma treatment alone, (2) plasma treatment followed by activation by 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), (3) plasma-initiated acrylic acid grafting, or (4) plasma-initiated acrylic acid grafting with activation by EDC and sulfo-NHS. The impact of each method on the surface chemistry of PHA was investigated using contact angle analysis and X-ray photoelectron spectroscopy. Each of the four treatments was shown to result in both increased hydrophilicity and in the modification of the surface functional groups. Modified surfaces were immersed in suspensions of phage T4 for immobilization. The highest level of phage binding was observed for the surfaces modified by plasma treatment alone. The change in chemical bond states observed for surfaces that underwent plasma treatment is suspected to be the cause of the increased binding of active phages. Plasma-treated surfaces were further analyzed through phage-staining and fluorescence microscopy to assess the surface density of immobilized phages and their capacity to capture hosts. The infective capability of attached phages was confirmed by exposing the phage-immobilized surfaces to the host bacteria Escherichia coli in both plaque and infection dynamic assays. Plasma-treated surfaces with immobilized phages displayed higher infectivity than surfaces treated with other methods; in fact, the equivalent initial multiplicity of infection was 2 orders of magnitude greater than with other methods. Control samples - prepared by immersing polymer surfaces in phage suspensions (without prior plasma treatment) - did not show any bacterial growth inhibition, suggesting they did not bind

Monitoring of Surface Subsidence of the Mining Area Based on Sbas

NASA Astrophysics Data System (ADS)

Zhu, Y.; Zhou, S.; Zang, D.; Lu, T.

2018-05-01

This paper has collected 7 scenes of L band PALSAR sensor radar data of a mine in FengCheng city, jiangxi province, using the Small-baseline Subset (SBAS) method to invert the surface subsidence of the mine. Baselines of interference less than 800m has been chosen to constitute short baseline differential interference atlas, using pixels whose average coherent coefficient was larger than or equal to 0.3 as like high coherent point target, using singular value decomposition (SVD) method to calculate deformation phase sequence based on these high coherent points, and the accumulation of settlements of study area of different period had been obtained, so as to reflect the ground surface settlement evolution of the settlement of the area. The results of the study has showed that: SBAS technology has overcome coherent problem of the traditionality D-InSAR technique, continuous deformation field of surface mining in time dimension of time could been obtained, characteristics of ground surface settlement of mining subsidence in different period has been displayed, so to improve the accuracy and reliability of the monitoring results.

Roles of surface water areas for water and solute cycle in Hanoi city, Viet Nam

NASA Astrophysics Data System (ADS)

Hayashi, Takeshi; Kuroda, Keisuke; Do Thuan, An; Tran Thi Viet, Nga; Takizawa, Satoshi

2013-04-01

Hanoi city, the capital of Viet Nam, has developed beside the Red river. Recent rapid urbanization of this city has reduced a large number of natural water areas such as lakes, ponds and canals not only in the central area but the suburban area. Contrary, the urbanization has increased artificial water areas such as pond for fish cultivation and landscaping. On the other hand, the urbanization has induced the inflow of waste water from households and various kinds of factories to these water areas because of delay of sewerage system development. Inflow of the waste water has induced eutrophication and pollution of these water areas. Also, there is a possibility of groundwater pollution by infiltration of polluted surface water. However, the role of these water areas for water cycle and solute transport is not clarified. Therefore, this study focuses on the interaction between surface water areas and groundwater in Hanoi city to evaluate appropriate land development and groundwater resource management. We are carrying out three approaches: a) understanding of geochemical characteristics of surface water and groundwater, b) monitoring of water levels of pond and groundwater, c) sampling of soil and pond sediment. Correlation between d18O and dD of precipitation (after GNIP), the Red River (after GNIR) and the water samples of this study showed that the groundwater is composed of precipitation, the Red River and surface water that has evaporation process. Contribution of the surface water with evaporation process was widely found in the study area. As for groundwater monitoring, the Holocene aquifers at two sites were in unconfined condition in dry season and the groundwater levels in the aquifer continued to increase through rainy season. The results of isotopic analysis and groundwater level monitoring showed that the surface water areas are one of the major groundwater sources. On the other hand, concentrations of dissolved Arsenic (filtered by 0.45um) in the pore

Converting biomass waste into microporous carbon with simultaneously high surface area and carbon purity as advanced electrochemical energy storage materials

NASA Astrophysics Data System (ADS)

Sun, Fei; Wang, Lijie; Peng, Yiting; Gao, Jihui; Pi, Xinxin; Qu, Zhibin; Zhao, Guangbo; Qin, Yukun

2018-04-01

Developing carbon materials featuring both high accessible surface area and high structure stability are desirable to boost the performance of constructed electrochemical electrodes and devices. Herein, we report a new type of microporous carbon (MPC) derived from biomass waste based on a simple high-temperature chemical activation procedure. The optimized MPC-900 possesses microporous structure, high surface area, partially graphitic structure, and particularly low impurity content, which are critical features for enhancing carbon-based electrochemical process. The constructed MPC-900 symmetric supercapacitor exhibits high performances in commercial organic electrolyte such as widened voltage window up to 3 V and thereby high energy/power densities (50.95 Wh kg-1 at 0.44 kW kg-1; 25.3 Wh kg-1 at 21.5 kW kg-1). Furthermore, a simple melt infiltration method has been employed to enclose SnO2 nanocrystals onto the carbon matrix of MPC-900 as a high-performance lithium storage material. The obtained SnO2-MPC composite with ultrafine SnO2 nanocrystals delivers high capacities (1115 mAh g-1 at 0.2 A g-1; 402 mAh g-1 at 10 A g-1) and high-rate cycling lifespan of over 2000 cycles. This work not only develops a microporous carbon with high carbon purity and high surface area, but also provides a general platform for combining electrochemically active materials.

Assessment of Surface Water Storage trends for increasing groundwater areas in India

NASA Astrophysics Data System (ADS)

Banerjee, Chandan; Kumar, D. Nagesh

2018-07-01

Recent studies based on Gravity Recovery and Climate Experiment (GRACE) satellite mission suggested that groundwater has increased in central and southern parts of India. However, surface water, which is an equally important source of water in these semi-arid areas has not been studied yet. In the present study, the study areas were outlined based on trends in GRACE data followed by trend identification in surface water storages and checking the hypothesis of causality. Surface Water Extent (SWE) and Surface Soil Moisture (SSM) derived from Moderate-resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) respectively, are selected as proxies of surface water storage (SWS). Besides SWE and SSM, trend test was performed for GRACE derived terrestrial water storage (TWS) for the study areas named as R1, R2, GOR1 and KOR1. Granger-causality test is used to test the hypothesis that rainfall is a causal factor of the inter-annual variability of SWE, SSM and TWS. Positive trends were observed in TWS for R1, R2 and GOR1 whereas SWE and SSM show increasing trends for all the study regions. Results suggest that rainfall is the granger-causal of all the storage variables for R1 and R2, the regions exhibiting the most significant positive trends in TWS.

Investigation of Aerosol Surface Area Estimation from Number and Mass Concentration Measurements: Particle Density Effect.

PubMed

Ku, Bon Ki; Evans, Douglas E

2012-04-01

For nanoparticles with nonspherical morphologies, e.g., open agglomerates or fibrous particles, it is expected that the actual density of agglomerates may be significantly different from the bulk material density. It is further expected that using the material density may upset the relationship between surface area and mass when a method for estimating aerosol surface area from number and mass concentrations (referred to as "Maynard's estimation method") is used. Therefore, it is necessary to quantitatively investigate how much the Maynard's estimation method depends on particle morphology and density. In this study, aerosol surface area estimated from number and mass concentration measurements was evaluated and compared with values from two reference methods: a method proposed by Lall and Friedlander for agglomerates and a mobility based method for compact nonspherical particles using well-defined polydisperse aerosols with known particle densities. Polydisperse silver aerosol particles were generated by an aerosol generation facility. Generated aerosols had a range of morphologies, count median diameters (CMD) between 25 and 50 nm, and geometric standard deviations (GSD) between 1.5 and 1.8. The surface area estimates from number and mass concentration measurements correlated well with the two reference values when gravimetric mass was used. The aerosol surface area estimates from the Maynard's estimation method were comparable to the reference method for all particle morphologies within the surface area ratios of 3.31 and 0.19 for assumed GSDs 1.5 and 1.8, respectively, when the bulk material density of silver was used. The difference between the Maynard's estimation method and surface area measured by the reference method for fractal-like agglomerates decreased from 79% to 23% when the measured effective particle density was used, while the difference for nearly spherical particles decreased from 30% to 24%. The results indicate that the use of particle density

The influence of lifestyle on airborne particle surface area doses received by different Western populations.

PubMed

Pacitto, A; Stabile, L; Moreno, T; Kumar, P; Wierzbicka, A; Morawska, L; Buonanno, G

2018-01-01

In the present study, the daily dose in terms of particle surface area received by citizens living in five cities in Western countries, characterized by different lifestyle, culture, climate and built-up environment, was evaluated and compared. For this purpose, the exposure to sub-micron particle concentration levels of the population living in Barcelona (Spain), Cassino (Italy), Guilford (United Kingdom), Lund (Sweden), and Brisbane (Australia) was measured through a direct exposure assessment approach. In particular, measurements of the exposure at a personal scale were performed by volunteers (15 per each population) that used a personal particle counter for different days in order to obtain exposure data in microenvironments/activities they resided/performed. Non-smoking volunteers performing non-industrial jobs were considered in the study. Particle concentration data allowed obtaining the exposure of the population living in each city. Such data were combined in a Monte Carlo method with the time activity pattern data characteristics of each population and inhalation rate to obtain the most probable daily dose in term of particle surface area as a function of the population gender, age, and nationality. The highest daily dose was estimated for citizens living in Cassino and Guilford (>1000 mm 2 ), whereas the lowest value was recognized for Lund citizens (around 100 mm 2 ). Indoor air quality, and in particular cooking and eating activities, was recognized as the main influencing factor in terms of exposure (and thus dose) of the population: then confirming that lifestyle (e.g. time spent in cooking activities) strongly affect the daily dose of the population. On the contrary, a minor or negligible contribution of the outdoor microenvironments was documented. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temporal sea-surface gravity changes observed near the source area prior to the 2011 Tohoku earthquake

NASA Astrophysics Data System (ADS)

Nakamura, T.; Tsuboi, S.

2013-12-01

Recent seismological studies suggested subsurface activities preceding the 2011 Tohoku earthquake; the occurrence of migration of seismicity (Kato et al., 2012) and slow slip events (Ito et al., 2013) in and around the source area one month before the mainshock. In this study, we investigated sea-surface gravity changes observed by the shipboard gravimeter mounted on research vessels before the mainshock. The vessels incidentally passed through the source area along almost the same cruise track twice, four months before and one month before the mainshock. Comparing the sea surface gravity in the former track with that in the latter after Bouguer correction, we find the gravity changes of approximately 7 mGal in coseismic slip areas near the trench axis during the three months. We find these gravity changes even in the crossing areas of the cruise tracks where seafloor topographies have no differences between the tracks. We also find that the topographic differences show positive changes but the gravity changes negative ones in other areas, which is a negative correlation inconsistent with the theoretical relationship between the topographic difference and the gravity change. These mean that the differences of seafloor topographies due to differences between the two cruise tracks are not main causes of the observed gravity changes there. The changes cannot also be explained by drifts of the gravimeter and geostrophic currents. Although we have not had any clear evidences, we speculate that the possible cause may be density increases around the seismogenic zone or uplifts of seafloor in order to explain the changes of this size. We estimate the density increases of 1.0 g/cm**3 in a disk with a radius of 40 km and a width of 200 m or the uplifts of several tens of meters in seafloor areas for the observed gravity changes. Our results indicate that sea-surface gravity observations may be one of valid approaches to monitor the approximate location of a possible great

Gold-film coating assisted femtosecond laser fabrication of large-area, uniform periodic surface structures.

PubMed

Feng, Pin; Jiang, Lan; Li, Xin; Rong, Wenlong; Zhang, Kaihu; Cao, Qiang

2015-02-20

A simple, repeatable approach is proposed to fabricate large-area, uniform periodic surface structures by a femtosecond laser. 20 nm gold films are coated on semiconductor surfaces on which large-area, uniform structures are fabricated. In the case study of silicon, cross-links and broken structures of laser induced periodic surface structures (LIPSSs) are significantly reduced on Au-coated silicon. The good consistency between the scanning lines facilitates the formation of large-area, uniform LIPSSs. The diffusion of hot electrons in the Au films increases the interfacial carrier densities, which significantly enhances interfacial electron-phonon coupling. High and uniform electron density suppresses the influence of defects on the silicon and further makes the coupling field more uniform and thus reduces the impact of laser energy fluctuations, which homogenizes and stabilizes large-area LIPSSs.

Protein-Nanoparticle Interactions: Improving Immobilized Lytic Enzyme Activity and Surface Energy Effects

NASA Astrophysics Data System (ADS)

Downs, Emily Elizabeth

Protein-nanostructure conjugates, particularly particles, are a subject of significant interest due to changes in their fundamental behavior compared to bulk surfaces. As the size scale of nano-structured materials and proteins are on the same order of magnitude, nanomaterial properties can heavily influence how proteins adsorb and conform to the surface. Previous work has demonstrated the ability of nanoscale surfaces to modulate protein activity, conformation, and retention by modifying the particle surface curvature, morphology, and surface charge. This work has improved our understanding of the protein material interactions, but a complete understanding is still lacking. The goal of this thesis is to investigate two missing areas of understanding using two distinct systems. The first system utilizes a particle with controlled surface energy to observe the impact of surface energy on protein-particle interactions, while the second system uses a modified Listeria-specific protein to determine how protein structure and flexibility affects protein adsorption and activity on particles. Spherical, amorphous, and uniformly doped Zn-silica particles with tailored surface energies were synthesized to understand the impact of surface energy on protein adsorption behavior. Particle surface energy increased with a decrease in particle size and greater dopant concentrations. Protein adsorption and structural loss increased with both particle size and particle surface energy. Higher surface energies promoted protein-particle association and increased protein unfolding. Particle curvature and protein steric hindrance effects limited adsorption and structural loss on smaller particles. Protein surface charge heterogeneity was also found to be linked to both protein adsorption and unfolding behavior on larger particles. Greater surface charge heterogeneity led to higher adsorption concentrations and multilayer formation. These multilayers transitioned from protein

Effects of decontamination work on riverine radiocaesium activity concentrations in Fukushima affected area

NASA Astrophysics Data System (ADS)

Taniguchi, K.; Onda, Y.; Yoshimura, K.; Smith, H.; Brake, W.; Kubo, T.; Kuramoto, T.; Sato, T.; Onuma, S.

2016-12-01

Radionuclides such as Cs-134 and Cs-137 were widely distributed in the area affected by the accident at Fukushima Daiichi nuclear power plant. The radionuclides were deposited on the surface, absorbed by soil particles, and transported via river systems to Pacific Ocean due to rainfall events. In order to reduce air dose rate surrounding residential area, decontamination works have been conducted between 2013 and 2016 Fiscal Years. In paddy field and farmland contaminated by the fallout, 5 cm of surface soil was stripped, and then clean sands put on the surface. This work could reduce radiocaesium inventory, while the coverage of vegetation was significantly decreased. Therefore, runoff characteristics in the decontaminated area were different before and after the decontamination. Activity concentrations of particulate Cs-137 were measured in Abukuma river system and 8 small catchments located in coastal zone of Fukushima affected area. In all monitoring sites, Cs-137 concentrations have decreased over an entire monitoring period. Kuchibuto river, which is a tributary of Abukuma river showed significant effect of decontamination. In Yamakiya district, in the watershed of the tributary, the decontamination work had conducted from 2013 FY to December 2015. Particulate Cs-137 concentration at two monitoring sites located in the district showed around 30% of decline in the beginning of 2014 FY whereas the decline was not so significant at sites in lower reach of the tributary. Decontaminated paddy field and farmland can be judged as the important source of suspended sediments in the tributary.

Surface area and volume determination of subgingival calculus using laser fluorescence.

PubMed

Shakibaie, Fardad; Walsh, Laurence J

2014-03-01

Visible red (655 nm) laser fluorescence (LF) devices are currently used for identifying deposits of subgingival calculus on the root surfaces of teeth during dental examination and treatment; however, it is not known how the fluorescence readings produced by commercially available LF systems correlate to the nature of the deposits. This laboratory study explored the correlation between LF digital readings and the surface area and volume of subgingival calculus deposits on teeth. A collection of 30 extracted human posterior teeth with various levels of subgingival deposits of calculus across 240 sites were used in a clinical simulation, with silicone impression material used to replicate periodontal soft tissues. The teeth were scored by two examiners by using three commercial LF systems (DIAGNOdent, DIAGNOdent Pen and KEY3). The silicone was removed, and the teeth were removed for photography at × 20 magnification under white or ultraviolet light. The surface area, thickness, and volume were calculated, and both linear least squares regression and nonlinear (Spearman's rank method) correlation coefficients were determined. Visible red LF digital readings showed better correlation to calculus volume than to surface area. Overall, the best performance was found for the KEY3 system (Spearman coefficient 0.59), compared to the Classic DIAGNOdent (0.56) and the DIAGNOdent Pen (0.49). These results indicate that while visible red LF systems vary somewhat in performance, their LF readings provide a useful estimation of the volume of subgingival calculus deposits present on teeth.

High-resolution surface analysis for extended-range downscaling with limited-area atmospheric models

NASA Astrophysics Data System (ADS)

Separovic, Leo; Husain, Syed Zahid; Yu, Wei; Fernig, David

2014-12-01

High-resolution limited-area model (LAM) simulations are frequently employed to downscale coarse-resolution objective analyses over a specified area of the globe using high-resolution computational grids. When LAMs are integrated over extended time frames, from months to years, they are prone to deviations in land surface variables that can be harmful to the quality of the simulated near-surface fields. Nudging of the prognostic surface fields toward a reference-gridded data set is therefore devised in order to prevent the atmospheric model from diverging from the expected values. This paper presents a method to generate high-resolution analyses of land-surface variables, such as surface canopy temperature, soil moisture, and snow conditions, to be used for the relaxation of lower boundary conditions in extended-range LAM simulations. The proposed method is based on performing offline simulations with an external surface model, forced with the near-surface meteorological fields derived from short-range forecast, operational analyses, and observed temperatures and humidity. Results show that the outputs of the surface model obtained in the present study have potential to improve the near-surface atmospheric fields in extended-range LAM integrations.

The Area of a Surface Generated by Revolving a Graph about Any Line

ERIC Educational Resources Information Center

Goins, Edray Herber; Washington, Talitha M.

2013-01-01

We discuss a general formula for the area of the surface that is generated by a graph [t[subscript 0], t[subscript 1] [right arrow] [the set of real numbers][superscript 2] sending t [maps to] (x(t), y(t)) revolved around a general line L : Ax + By = C. As a corollary, we obtain a formula for the area of the surface formed by revolving y = f(x)…

Investigation on large-area fabrication of vivid shark skin with superior surface functions

NASA Astrophysics Data System (ADS)

Chen, Huawei; Zhang, Xin; Ma, Lingxi; Che, Da; Zhang, Deyuan; Sudarshan, T. S.

2014-10-01

Shark skin has attracted worldwide attention because of its superior drag reduction, antifouling performance induced from its unique surface morphology. Although the vivid shark skin has been fabricated by a bio-replicated micro-imprinting approach in previous studies and superior drag reduction effect has been validated in water tunnel, continuous large-area fabrication is still an obstacle to wide apply. In this paper, one novel bio-replication coating technology is proposed for large-area transfer of shark skin based on rapid UV curable paint. Apart from design of coating system, bio-replication accuracy of surface morphology was validated about 97% by comparison between shark skin template and coating surface morphology. Finally, the drag reduction and anti-fouling function of coating surface were tested in water tunnel and open algae pond respectively. Drag reduction rate of coating surface was validated about 12% higher and anti-fouling was proved to about hundred times ameliorate, all of which are more excellent than simple 2D riblet surface.

High Surface Area of Porous Silicon Drives Desorption of Intact Molecules

PubMed Central

Northen, Trent R.; Woo, Hin-Koon; Northen, Michael T.; Nordström, Anders; Uritboonthail, Winnie; Turner, Kimberly L.; Siuzdak, Gary

2007-01-01

The surface structure of porous silicon used in desorption/ionization on porous silicon (DIOS) mass analysis is known to play a primary role in the desorption/ionization (D/I) process. In this study, mass spectrometry and scanning electron microscopy (SEM) are used to examine the correlation between intact ion generation with surface ablation, and surface morphology. The DIOS process is found to be highly laser energy dependent and correlates directly with the appearance of surface ions (Sin+ and OSiH+). A threshold laser energy for DIOS is observed (10 mJ/cm2), which supports that DIOS is driven by surface restructuring and is not a strictly thermal process. In addition, three DIOS regimes are observed which correspond to surface restructuring and melting. These results suggest that higher surface area silicon substrates may enhance DIOS performance. A recent example which fits into this mechanism is silicon nanowires surface which have a high surface energy and concomitantly requires lower laser energy for analyte desorpton. PMID:17881245

Mechanochemical activation and gallium and indiaarsenides surface catalycity

NASA Astrophysics Data System (ADS)

Kirovskaya, I. A.; Mironova, E. V.; Umansky, I. V.; Brueva, O. Yu; Murashova, A. O.; Yureva, A. V.

2018-01-01

The present work has been carried out in terms of determining the possibilities for a clearer identification of the active sites nature, intermediate surface compounds nature, functional groups during adsorption and catalysis, activation of the diamond-like semiconductors surface (in particular, the AIIIBV type) based on mechanochemical studies of the “reaction medium (H2O, iso-C3H7OH) - dispersible semiconductor (GaAs, InAs)” systems. As a result, according to the read kinetic curves of dispersion in water, both acidification and alkalinization of the medium have been established and explained; increased activity of the newly formed surface has been noted; intermediate surface compounds, functional groups appearing on the real surface and under H2O adsorption conditions, adsorption and catalytic decomposition of iso-C3H7OH have been found (with explanation of the origin). The unconcealed role of coordinatively unsaturated atoms as active sites of these processes has been shown; the relative catalytic activity of the semiconductors studied has been evaluated. Practical recommendations on the preferred use of gallium arsenide in semiconductor gas analysis and semiconductor catalysis have been given in literature searches, great care should be taken in constructing both.

Surface and Active Layer Pore Water Chemistry from Ice Wedge Polygons, Barrow, Alaska, 2013-2014

DOE Data Explorer

David E. Graham; Baohua Gu; Elizabeth M. Herndon; Stan D. Wullschleger; Ziming Yang; Liyuan Liang

2016-11-10

This data set reports the results of spatial surveys of aqueous geochemistry conducted at Intensive Site 1 of the Barrow Environmental Observatory in 2013 and 2014 (Herndon et al., 2015). Surface water and soil pore water samples were collected from multiple depths within the tundra active layer of different microtopographic features (troughs, ridges, center) of a low-centered polygon (area A), high-centered polygon (area B), flat-centered polygon (area C), and transitional polygon (area D). Reported analytes include dissolved organic and inorganic carbon, dissolved carbon dioxide and methane, major inorganic anions, and major and minor cations.

Comparative Study of Surface-Active Properties and Antimicrobial Activities of Disaccharide Monoesters

PubMed Central

Zhang, Xi; Song, Fei; Taxipalati, Maierhaba; Wei, Wei; Feng, Fengqin

2014-01-01

The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect. PMID:25531369

Effect of wrinkles on the surface area of graphene: toward the design of nanoelectronics.

PubMed

Qin, Zhao; Taylor, Michael; Hwang, Mary; Bertoldi, Katia; Buehler, Markus J

2014-11-12

Graphene has attracted intense attention to the use in extreme applications. However, its small thickness facilitates wrinkle formation, and it is not clear how such structural change affects its area-specific capacitance. Herein, we combine molecular dynamics and continuum mechanics-based simulations to study the changes in surface area induced by wrinkles. We find that the high specific surface area of graphene can only be affected up to 2% regardless of loading conditions, geometry, and defects.

30 CFR 921.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... surface coal mining operations. 921.764 Section 921.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... mining operations. Part 764 of this chapter, State Processes for Designating Areas Unsuitable for Surface...

30 CFR 933.764 - Process for designating areas unsuitable for surface coal mining operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... surface coal mining operations. 933.764 Section 933.764 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS... mining operations. Part 764 of this chapter, State Processes for Designatng Areas Unsuitable for Surface...

A key parameter on the adsorption of diluted aniline solutions with activated carbons: The surface oxygen content.

PubMed

Pardo, Beatrice; Ferrer, Nabí; Sempere, Julià; Gonzalez-Olmos, Rafael

2016-11-01

A total of 11 different commercial activated carbons (AC) with well characterized textural properties and oxygen surface content were tested as adsorbents for the removal of aniline as a target water pollutant. The maximum adsorption capacity of aniline for the studied AC was from 138.9 to 257.9 mg g(-1) at 296.15 K and it was observed to be strongly related to the textural properties of the AC, mainly with the BET surface area and the micropore volume. It was not observed any influence of the oxygen surface content of the AC on the maximum adsorption capacity. However, it was found that at low aniline aqueous concentration, the presence of oxygen surface groups plays a dominant role during the adsorption. A high concentration of oxygen surface groups, mainly carboxylic and phenolic groups, decreases the aniline adsorption regardless of the surface area of the AC. Copyright © 2016 Elsevier Ltd. All rights reserved.

Active Surfaces and Interfaces of Soft Materials

NASA Astrophysics Data System (ADS)

Wang, Qiming

A variety of intriguing surface patterns have been observed on developing natural systems, ranging from corrugated surface of white blood cells at nanometer scales to wrinkled dog skins at millimeter scales. To mimetically harness functionalities of natural morphologies, artificial transformative skin systems by using soft active materials have been rationally designed to generate versatile patterns for a variety of engineering applications. The study of the mechanics and design of these dynamic surface patterns on soft active materials are both physically interesting and technologically important. This dissertation starts with studying abundant surface patterns in Nature by constructing a unified phase diagram of surface instabilities on soft materials with minimum numbers of physical parameters. Guided by this integrated phase diagram, an electroactive system is designed to investigate a variety of electrically-induced surface instabilities of elastomers, including electro-creasing, electro-cratering, electro-wrinkling and electro-cavitation. Combing experimental, theoretical and computational methods, the initiation, evolution and transition of these instabilities are analyzed. To apply these dynamic surface instabilities to serving engineering and biology, new techniques of Dynamic Electrostatic Lithography and electroactive anti-biofouling are demonstrated.

High-energy supercapacitors based on hierarchical porous carbon with an ultrahigh ion-accessible surface area in ionic liquid electrolytes

NASA Astrophysics Data System (ADS)

Zhong, Hui; Xu, Fei; Li, Zenghui; Fu, Ruowen; Wu, Dingcai

2013-05-01

A very important yet really challenging issue to address is how to greatly increase the energy density of supercapacitors to approach or even exceed those of batteries without sacrificing the power density. Herein we report the fabrication of a new class of ultrahigh surface area hierarchical porous carbon (UHSA-HPC) based on the pore formation and widening of polystyrene-derived HPC by KOH activation, and highlight its superior ability for energy storage in supercapacitors with ionic liquid (IL) as electrolyte. The UHSA-HPC with a surface area of more than 3000 m2 g-1 shows an extremely high energy density, i.e., 118 W h kg-1 at a power density of 100 W kg-1. This is ascribed to its unique hierarchical nanonetwork structure with a large number of small-sized nanopores for IL storage and an ideal meso-/macroporous network for IL transfer.A very important yet really challenging issue to address is how to greatly increase the energy density of supercapacitors to approach or even exceed those of batteries without sacrificing the power density. Herein we report the fabrication of a new class of ultrahigh surface area hierarchical porous carbon (UHSA-HPC) based on the pore formation and widening of polystyrene-derived HPC by KOH activation, and highlight its superior ability for energy storage in supercapacitors with ionic liquid (IL) as electrolyte. The UHSA-HPC with a surface area of more than 3000 m2 g-1 shows an extremely high energy density, i.e., 118 W h kg-1 at a power density of 100 W kg-1. This is ascribed to its unique hierarchical nanonetwork structure with a large number of small-sized nanopores for IL storage and an ideal meso-/macroporous network for IL transfer. Electronic supplementary information (ESI) available: Sample preparation, material characterization, electrochemical characterization and specific mass capacitance and energy density. See DOI: 10.1039/c3nr00738c

Investigation of Aerosol Surface Area Estimation from Number and Mass Concentration Measurements: Particle Density Effect

PubMed Central

Ku, Bon Ki; Evans, Douglas E.

2015-01-01

For nanoparticles with nonspherical morphologies, e.g., open agglomerates or fibrous particles, it is expected that the actual density of agglomerates may be significantly different from the bulk material density. It is further expected that using the material density may upset the relationship between surface area and mass when a method for estimating aerosol surface area from number and mass concentrations (referred to as “Maynard’s estimation method”) is used. Therefore, it is necessary to quantitatively investigate how much the Maynard’s estimation method depends on particle morphology and density. In this study, aerosol surface area estimated from number and mass concentration measurements was evaluated and compared with values from two reference methods: a method proposed by Lall and Friedlander for agglomerates and a mobility based method for compact nonspherical particles using well-defined polydisperse aerosols with known particle densities. Polydisperse silver aerosol particles were generated by an aerosol generation facility. Generated aerosols had a range of morphologies, count median diameters (CMD) between 25 and 50 nm, and geometric standard deviations (GSD) between 1.5 and 1.8. The surface area estimates from number and mass concentration measurements correlated well with the two reference values when gravimetric mass was used. The aerosol surface area estimates from the Maynard’s estimation method were comparable to the reference method for all particle morphologies within the surface area ratios of 3.31 and 0.19 for assumed GSDs 1.5 and 1.8, respectively, when the bulk material density of silver was used. The difference between the Maynard’s estimation method and surface area measured by the reference method for fractal-like agglomerates decreased from 79% to 23% when the measured effective particle density was used, while the difference for nearly spherical particles decreased from 30% to 24%. The results indicate that the use of

BET surface area distributions in polar stream sediments: Implications for silicate weathering in a cold-arid environment

USGS Publications Warehouse

Marra, Kristen R.; Elwood Madden, Megan E; Soreghan, Gerilyn S.; Hall, Brenda L

2014-01-01

BET surface area values are critical for quantifying the amount of potentially reactive sediments available for chemical weathering and ultimately, prediction of silicate weathering fluxes. BET surface area values of fine-grained (<62.5 μm) sediment from the hyporheic zone of polar glacial streams in the McMurdo Dry Valleys, Antarctica (Wright and Taylor Valleys) exhibit a wide range (2.5–70.6 m2/g) of surface area values. Samples from one (Delta Stream, Taylor Valley) of the four sampled stream transects exhibit high values (up to 70.6 m2/g), which greatly exceed surface area values from three temperate proglacial streams (0.3–12.1 m2/g). Only Clark stream in Wright Valley exhibits a robust trend with distance, wherein surface area systematically decreases (and particle size increases) in the mud fraction downstream, interpreted to reflect rapid dissolution processes in the weathering environment. The remaining transects exhibit a range in variability in surface area distributions along the length of the channel, likely related to variations in eolian input to exposed channel beds, adjacent snow drifts, and to glacier surfaces, where dust is trapped and subsequently liberated during summer melting. Additionally, variations in stream discharge rate, which mobilizes sediment in pulses and influences water:rock ratios, the origin and nature of the underlying drift material, and the contribution of organic acids may play significant roles in the production and mobilization of high-surface area sediment. This study highlights the presence of sediments with high surface area in cold-based glacier systems, which influences models of chemical denudation rates and the impact of glacial systems on the global carbon cycle.

Implications of contamination and surface area ratios for Langmuir probe diagnostics on CubeSats

NASA Astrophysics Data System (ADS)

Suresh, P.; Swenson, C.

2009-12-01

Theories describing the current collected by a biased probe under various conditions are necessary for such observation to be used to accurately determine plasma properties. Langmuir probes are routinely used on spacecraft to measure plasma parameters such as density, temperature, and vehicle charging. The collected current is a function of the potential between the surrounding plasma and probe surface. There have been both observations of and concepts for unaccounted variations of this potential which limit the application of Langmuir probe theory for determining plasma properties. These variations occur due to spatial variations of the work function across the probe surface due to non-uniformity of the crystalline surface properties and surface contamination of the probe. Currently we do not have theoretical expressions which consider these factors as first principles in their derivation. In the event of these surface potential variations, the analysis of the plasma using the currently available theories of the Langmuir probe yield erroneous results. We present a theory which models the current as a function of the surface potential variations. Another consideration for Langmuir probes on CubeSats is the ratio of the probe area to the return current collection area. If the area ratio is unfavorable this can also lead to erroneous results in the interpretation of observations. A mathematical formulation of the current collected by the probe for contaminated surfaces is presented and compared with data from a Langmuir probe flown on a sounding rocket mission. The implications of using Langmuir probes on CubeSats given the engineering limitations of probe cleanliness and area ratios are reviewed.

Surface photoisomerization activity vs. functionalization of azobenzene derivatives

NASA Astrophysics Data System (ADS)

Berbil-Bautista, Luis; Cho, Jongweon; Levy, Niv; Comstock, Matthew J.; Poulsen, Dan; Frechet, Jean M. J.; Crommie, Michael F.

2008-03-01

Azobenzene and its derivatives can be reversibly photoisomerized between their cis and trans conformations in solution. The photoisomerization process is wavelength selective and results in a large length change. Hence, it is ideally suited to actuating molecular nanomachines on surfaces. However, it has recently been shown [1] that to recover photoisomerization activity on a metallic surface molecules must be functionalized with bulky spacing groups to decouple the optically active part of the molecule from the surface. This results in various trade-offs between molecular optical activity and overall flexibility/functionality. We have explored the photoisomerization activity of different azobenzene derivatives on metallic surfaces using a scanning tunneling microscope (STM) with optical access to the sample. The effects on molecular photo-activity and self-assembly for different substituent groups has been studied. [1] Matthew J. Comstock, Niv Levy, Armen Kirakosian, Jongweon Cho, Frank Lauterwasser, Jessica H. Harvey, David A. Strubbe, Jean M. J. Fr'echet, Dirk Trauner, Steven G. Louie, and Michael F. Crommie Phys. Rev. Lett. 99, 038301 (2007)

Surface activation of dyed fabric for cellulase treatment.

PubMed

Schimper, Christian B; Ibanescu, Constanta; Bechtold, Thomas

2011-10-01

Surface activation of fabric made from cellulose fibres, such as viscose, lyocell, modal fibres and cotton, can be achieved by printing of a concentrated NaOH-containing paste. From the concentration of reducing sugars formed in solution, an increase in intensity of the cellulase hydrolysis by a factor of six to eight was observed, which was mainly concentrated at the activated parts of the fabric surface. This method of local activation is of particular interest for modification of materials that have been dyed with special processes to attain an uneven distribution of dyestuff within the yarn cross-section, e.g., indigo ring-dyed denim yarn for jeans production. Fabrics made from regenerated cellulose fibres were used as model substrate to express the effects of surface activation on indigo-dyed material. Wash-down experiments on indigo-dyed denim demonstrated significant colour removal from the activated surface at low overall weight loss of 4-5%. The method is of relevance for a more eco-friendly processing of jeans in the garment industry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and surface activity properties of alkylphenol polyoxyethylene nonionic trimeric surfactants

NASA Astrophysics Data System (ADS)

Yang, Fang; Li, Gang; Qi, Jian; Zhang, Song-Mei; Liu, Rong

2010-10-01

A series of trimeric n-alkylphenol polyoxyethylene surfactants (TAP) were successfully synthesized and the molecular structure were confirmed by NMR, FTIR spectrum and elemental analysis. Using the same synthesis route, the trimeric nonylphenol polyoxyethylene surfactant (TNP) was synthesized using industrial product nonylphenol and paraformaldehyde, and its molecular structure was characterized by 1HNMR, FTIR spectrum and elemental analysis. The optimal reaction conditions were established. The surface activity properties of TAP and TNP (such as the critical micelle concentration (cmc), the values of surface tension at the cmc ( γcmc), the maximum surface excess concentration ( Γcmc), and the minimum surface area per surfactant molecule ( Acmc)), were determined by means of Wilhelmy plate method and steady-state fluorescence probe method, respectively. The experimental results show that the lengths of the hydrophilic group oxyethylene (EO) chains and hydrophobic group methylene chains have an influence on the cmc, γcmc, Γcmc, and Acmc of series of surfactants. Furthermore, TAP are arranged to staggered three-dimensional array mode at the air-water interface, which has exhibited better surface properties, such as low cmc values, strong adsorption affinities and wet abilities.

The use of total lake-surface area as an indicator of climatic change: Examples from the Lahontan basin

USGS Publications Warehouse

Benson, L.V.; Paillet, Frederick L.

1989-01-01

Variation in the size of lakes in the Lahontan basin is topographically constrained. River diversion also has played a major role in regulating lake size in Lahontan subbasins. The proper gage of lake response to change in the hydrologic balance is neither lake depth (level) nor lake volume but instead lake-surface area. Normalization of surface area is necessary when comparing surface areas of lakes in basins having different topographies. To a first approximation, normalization can be accomplished by dividing the paleosurface area of a lake by its mean-historical, reconstructed surface area. ?? 1989.

43 CFR 1610.7-1 - Designation of areas unsuitable for surface mining.

Code of Federal Regulations, 2011 CFR

2011-10-01

... surface mining. 1610.7-1 Section 1610.7-1 Public Lands: Interior Regulations Relating to Public Lands... mining. (a)(1) The planning process is the chief process by which public land is reviewed to assess whether there are areas unsuitable for all or certain types of surface coal mining operations under...

Adsorption of cadmium by activated carbon cloth: influence of surface oxidation and solution pH.

PubMed

Rangel-Mendez, J R; Streat, M

2002-03-01

The surface of activated carbon cloth (ACC), based on polyacrylonitrile fibre as a precursor, was oxidised using nitric acid, ozone and electrochemical oxidation to enhance cadmium ion exchange capacity. Modified adsorbents were physically and chemically characterised by pH titration, direct titration, X-ray photoelectron spectroscopy, elemental analysis, surface area and porosimetry, and scanning electron microscopy. BET surface area decreased after oxidation, however, the total ion exchange capacity increased by a factor of approximately 3.5 compared to the commercial as-received ACC. A very significant increase in cadmium uptake, by a factor of 13, was observed for the electrochemically oxidised ACC. Equilibrium sorption isotherms were determined at pH 4, 5 and 6 and these showed that cadmium uptake increased with increasing pH. There was clear evidence of physical damage to ozone-oxidised fibre, however, acid and electrochemically oxidised samples were completely stable.

High surface area nanocrystalline hausmannite synthesized by a solvent-free route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrera-Miranda, Daniel; Ponrouch, Alexandre; Pons, Josefina

Highlights: ► High surface area Mn{sub 3}O{sub 4} nanoparticles obtained by a solvent-free low temperature route. ► 3,6,9-Trioxadecanoic acid allows to obtain nanocrystalline hausmannite. ► Tape casted electrodes show up to 300 mAh g{sup −1} capacity after more than 40 cycles at a C/3 rate. ► Upper cut off voltage strongly influences capacity retention upon cycling at high C rates. -- Abstract: Nanocrystalline high surface area Mn{sub 3}O{sub 4} powder was obtained at low temperature by a solvent-free route. The precursor was a mixture of manganese (II) acetate, 3,6,9-trioxadecanoic acid (TODA) and ammonium acetate that were intimately mixed by groundingmore » in an agate mortar. Nanocrystalline Mn{sub 3}O{sub 4} was obtained by thermal treatment at 120 °C. Powder X-ray diffraction, selected area electron diffraction, high resolution transmission electron microscopy, and Fourier transformed infrared characterization confirmed the formation of the hausmannite phase. The as-prepared mesoporous material has high specific surface area (120 m{sup 2} g{sup −1}). The performances of tape casted Mn{sub 3}O{sub 4} nanopowder electrodes were investigated as anode material for lithium ion batteries. High capacity values were achieved at diverse C rates. Capacity fading was found to be dependent on the upper cut off voltage, the presence of a plateau at 2.25 V vs. Li{sup +}/Li being detrimental for long term cyclability.« less

Facile synthesis of porous graphene-like carbon nitride nanosheets with high surface area and enhanced photocatalytic activity via one-step catalyst-free solution self-polymerization

NASA Astrophysics Data System (ADS)

Wu, Shikai; Wen, Shengwu; Xu, Xinmei; Huang, Guozhi; Cui, Yifan; Li, Jinyu; Qu, Ailan

2018-04-01

Porous graphite carbon nitride nanosheets (g-C3N4) are achieved via one-step catalyst-free solution self-polymerization from a single melamine precursor. The resultant porous g-C3N4 nanosheets with the best photodegradation capacity provided the surface area of 669.15 m2/g, which is superior to the surface area of any other porous g-C3N4 reported. Results showed enhanced adsorption and degradation capacity of methyl orange (MO) under UV-visible light irradiation (λ > 350 nm) compared to bulk g-C3N4. The MO oxidation of the porous g-C3N4 nanosheets is driven mostly by the participation of holes, and secondly by rad O2- and rad OH radicals. This approach shed lights on porous g-C3N4 production simply by self-polycondensation of single functional monomer. It also provided a low-cost and eco-friendly method to facilely mass-produce g-C3N4 nanosheets with high surface area for many potential applications.

Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

NASA Astrophysics Data System (ADS)

Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I.; Qamaruddin, Muhammad; Yamani, Zain H.

2015-02-01

Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.

New model for estimating the relationship between surface area and volume in the human body using skeletal remains.

PubMed

Kasabova, Boryana E; Holliday, Trenton W

2015-04-01

A new model for estimating human body surface area and body volume/mass from standard skeletal metrics is presented. This model is then tested against both 1) "independently estimated" body surface areas and "independently estimated" body volume/mass (both derived from anthropometric data) and 2) the cylindrical model of Ruff. The model is found to be more accurate in estimating both body surface area and body volume/mass than the cylindrical model, but it is more accurate in estimating body surface area than it is for estimating body volume/mass (as reflected by the standard error of the estimate when "independently estimated" surface area or volume/mass is regressed on estimates derived from the present model). Two practical applications of the model are tested. In the first test, the relative contribution of the limbs versus the trunk to the body's volume and surface area is compared between "heat-adapted" and "cold-adapted" populations. As expected, the "cold-adapted" group has significantly more of its body surface area and volume in its trunk than does the "heat-adapted" group. In the second test, we evaluate the effect of variation in bi-iliac breadth, elongated or foreshortened limbs, and differences in crural index on the body's surface area to volume ratio (SA:V). Results indicate that the effects of bi-iliac breadth on SA:V are substantial, while those of limb lengths and (especially) the crural index are minor, which suggests that factors other than surface area relative to volume are driving morphological variation and ecogeographical patterning in limb prorportions. © 2014 Wiley Periodicals, Inc.

Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

NASA Astrophysics Data System (ADS)

Ranjan Nayak, Rati; Yamada, Tasuku; Matsuoka, Hideki

2011-09-01

Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

Surface-Bound Casein Modulates the Adsorption and Activity of Kinesin on SiO2 Surfaces

PubMed Central

Ozeki, Tomomitsu; Verma, Vivek; Uppalapati, Maruti; Suzuki, Yukiko; Nakamura, Mikihiko; Catchmark, Jeffrey M.; Hancock, William O.

2009-01-01

Abstract Conventional kinesin is routinely adsorbed to hydrophilic surfaces such as SiO2. Pretreatment of surfaces with casein has become the standard protocol for achieving optimal kinesin activity, but the mechanism by which casein enhances kinesin surface adsorption and function is poorly understood. We used quartz crystal microbalance measurements and microtubule gliding assays to uncover the role that casein plays in enhancing the activity of surface-adsorbed kinesin. On SiO2 surfaces, casein adsorbs as both a tightly bound monolayer and a reversibly bound second layer that has a dissociation constant of 500 nM and can be desorbed by washing with casein-free buffer. Experiments using truncated kinesins demonstrate that in the presence of soluble casein, kinesin tails bind well to the surface, whereas kinesin head binding is blocked. Removing soluble casein reverses these binding profiles. Surprisingly, reversibly bound casein plays only a moderate role during kinesin adsorption, but it significantly enhances kinesin activity when surface-adsorbed motors are interacting with microtubules. These results point to a model in which a dynamic casein bilayer prevents reversible association of the heads with the surface and enhances association of the kinesin tail with the surface. Understanding protein-surface interactions in this model system should provide a framework for engineering surfaces for functional adsorption of other motor proteins and surface-active enzymes. PMID:19383474

A preliminary assessment of land-surface subsidence in the El Paso area, Texas

USGS Publications Warehouse

Land, L.F.; Armstrong, C.A.

1985-01-01

In addition to regional subsidence, local subsidence is indicated by observable surface fractures but has not been verified by precise leveling. These local areas coincide with areas that historically were swamps along the Rio Grande.

Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

NASA Astrophysics Data System (ADS)

Kimura, T.

2014-11-01

Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene) (PS-b-PEO) diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical) macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

Brain development during adolescence: A mixed-longitudinal investigation of cortical thickness, surface area, and volume.

PubMed

Vijayakumar, Nandita; Allen, Nicholas B; Youssef, George; Dennison, Meg; Yücel, Murat; Simmons, Julian G; Whittle, Sarah

2016-06-01

What we know about cortical development during adolescence largely stems from analyses of cross-sectional or cohort-sequential samples, with few studies investigating brain development using a longitudinal design. Further, cortical volume is a product of two evolutionarily and genetically distinct features of the cortex - thickness and surface area, and few studies have investigated development of these three characteristics within the same sample. The current study examined maturation of cortical thickness, surface area and volume during adolescence, as well as sex differences in development, using a mixed longitudinal design. 192 MRI scans were obtained from 90 healthy (i.e., free from lifetime psychopathology) adolescents (11-20 years) at three time points (with different MRI scanners used at time 1 compared to 2 and 3). Developmental trajectories were estimated using linear mixed models. Non-linear increases were present across most of the cortex for surface area. In comparison, thickness and volume were both characterised by a combination of non-linear decreasing and increasing trajectories. While sex differences in volume and surface area were observed across time, no differences in thickness were identified. Furthermore, few regions exhibited sex differences in the cortical development. Our findings clearly illustrate that volume is a product of surface area and thickness, with each exhibiting differential patterns of development during adolescence, particularly in regions known to contribute to the development of social-cognition and behavioral regulation. These findings suggest that thickness and surface area may be driven by different underlying mechanisms, with each measure potentially providing independent information about brain development. Hum Brain Mapp 37:2027-2038, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

INTERFRAGMENTARY SURFACE AREA AS AN INDEX OF COMMINUTION SEVERITY IN CORTICAL BONE IMPACT

PubMed Central

Beardsley, Christina L.; Anderson, Donald D.; Marsh, J. Lawrence; Brown, Thomas D.

2008-01-01

Summary A monotonic relationship is expected between energy absorption and fracture surface area generation for brittle solids, based on fracture mechanics principles. It was hypothesized that this relationship is demonstrable in bone, to the point that on a continuous scale, comminuted fractures created with specific levels of energy delivery could be discriminated from one another. Using bovine cortical bone segments in conjunction with digital image analysis of CT fracture data, the surface area freed by controlled impact fracture events was measured. The results demonstrated a statistically significant (p<0.0001) difference in measured de novo surface area between three specimen groups, over a range of input energies from 0.423 to 0.702 J/g. Local material properties were also incorporated into these measurements via CT Hounsfield intensities. This study confirms that comminution severity of bone fractures can indeed be measured on a continuous scale, based on energy absorption. This lays a foundation for similar assessments in human injuries. PMID:15885492

Potential effects of groundwater and surface water contamination in an urban area, Qus City, Upper Egypt

NASA Astrophysics Data System (ADS)

Abdalla, Fathy; Khalil, Ramadan

2018-05-01

The potential effects of anthropogenic activities, in particular, unsafe sewage disposal practices, on shallow groundwater in an unconfined aquifer and on surface water were evaluated within an urban area by the use of hydrogeological, hydrochemical, and bacteriological analyses. Physicochemical and bacteriological data was obtained from forty-five sampling points based on33 groundwater samples from variable depths and 12 surface water samples. The pollution sources are related to raw sewage and wastewater discharges, agricultural runoff, and wastewater from the nearby Paper Factory. Out of the 33 groundwater samples studied, 17 had significant concentrations of NO3-, Cl- and SO42-, and high bacteria counts. Most of the water samples from the wells contained high Fe, Mn, Pb, Zn, Cd, and Cr. The majority of surface water samples presented high NO3- concentrations and high bacteria counts. A scatter plot of HCO3- versus Ca indicates that 58% of the surface water samples fall within the extreme contamination zone, while the others are within the mixing zone; whereas 94% of groundwater samples showed evidence of mixing between groundwater and wastewater. The bacteriological assessment showed that all measured surface and groundwater samples contained Escherichia coli and total coliform bacteria. A risk map delineated four classes of contamination, namely, those sampling points with high (39.3%), moderate (36.3%), low (13.3%), and very low (11.1%) levels of contamination. Most of the highest pollution points were in the middle part of the urban area, which suffers from unmanaged sewage and industrial effluents. Overall, the results demonstrate that surface and groundwater in Qus City are at high risk of contamination by wastewater since the water table is shallow and there is a lack of a formal sanitation network infrastructure. The product risk map is a useful tool for prioritizing zones that require immediate mitigation and monitoring.

Location of unaccessible implant surface areas during debridement in simulated peri-implantitis therapy.

PubMed

Steiger-Ronay, Valerie; Merlini, Andrea; Wiedemeier, Daniel B; Schmidlin, Patrick R; Attin, Thomas; Sahrmann, Philipp

2017-11-28

An in vitro model for peri-implantitis treatment was used to identify areas that are clinically difficult to clean by analyzing the pattern of residual stain after debridement with commonly employed instruments. Original data from two previous publications, which simulated surgical (SA) and non-surgical (NSA) implant debridement on two different implant systems respectively, were reanalyzed regarding the localization pattern of residual stains after instrumentation. Two blinded examiners evaluated standardized photographs of 360 initially ink-stained dental implants, which were cleaned at variable defect angulations (30, 60, or 90°), using different instrument types (Gracey curette, ultrasonic scaler or air powder abrasive device) and treatment approaches (SA or NSA). Predefined implant surface areas were graded for residual stain using scores ranging from one (stain-covered) to six (clean). Score differences between respective implant areas were tested for significance by pairwise comparisons using Wilcoxon-rank-sum-tests with a significance level α = 5%. Best scores were found at the machined surface areas (SA: 5.58 ± 0.43, NSA: 4.76 ± 1.09), followed by the tips of the threads (SA: 4.29 ± 0.44, NSA: 4.43 ± 0.61), and areas between threads (SA: 3.79 ± 0.89, NSA: 2.42 ± 1.11). Apically facing threads were most difficult to clean (SA: 1.70 ± 0.92, NSA: 2.42 ± 1.11). Here, air powder abrasives provided the best results. Machined surfaces at the implant shoulder were well accessible and showed least amounts of residual stain. Apically facing thread surfaces constituted the area with most residual stain regardless of treatment approach.

Area densitometry using rotating Scheimpflug photography for posterior capsule opacification and surface light scattering analyses.

PubMed

Minami, Keiichiro; Honbo, Masato; Mori, Yosai; Kataoka, Yasushi; Miyata, Kazunori

2015-11-01

To compare area densitometry analysis using rotating Scheimpflug photography in quantifications of posterior capsule opacification (PCO) and surface light scattering with previous anterior-segment analyzer measurement. Miyata Eye Hospital, Miyazaki, Japan. Prospective observational case series. Scheimpflug images of eyes with foldable intraocular lenses (IOLs) were obtained using rotating and fixed Scheimpflug photography. Area densitometry on the posterior and anterior surfaces was conducted for PCO and surface light scattering analyses, respectively, with an identical area size. Correlation between two measurements was analyzed using linear regression. The study included 105 eyes of 74 patients who received IOLs 1 to 18 years (mean, 4.9 ± 4.5 years) postoperatively. In the PCO analysis on the posterior IOL surface, there was a significant correlation between the two measurements (P < .001, R(2) = 0.60). In the surface light scattering analysis, a significant and higher correlation was obtained (P < .001, R(2) = 0.91) until the fixed Scheimpflug photography exhibited saturation due to intensive scatterings. Area densitometry combined with a rotating Scheimpflug photography was exchangeable to previously established densitometry measurement, and allowed successive evaluation in longer-term observations. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

A feasible strategy to balance the crystallinity and specific surface area of metal oxide nanocrystals

NASA Astrophysics Data System (ADS)

Zhang, Q. P.; Xu, X. N.; Liu, Y. T.; Xu, M.; Deng, S. H.; Chen, Y.; Yuan, H.; Yu, F.; Huang, Y.; Zhao, K.; Xu, S.; Xiong, G.

2017-04-01

Practical, efficient synthesis of metal oxide nanocrystals with good crystallinity and high specific surface area by a modified polymer-network gel method is demonstrated, taking ZnO nanocrystals as an example. A novel stepwise heat treatment yields significant improvement in crystal quality. Such nanophase materials can effectively degrade common organic dyes under solar radiation and can perform very well in photo-assisted detection of NO2 gas. Other typical metal oxide nanocrystals with good crystallinity and high specific surface area were also synthesized successfully under similar conditions. This work provides a general strategy for the synthesis of metal oxide nanocrystals, balancing the crystallinity and specific surface area.

Unrivaled combination of surface area and pore volume in micelle-templated carbon for supercapacitor energy storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokrzywinski, Jesse; Keum, Jong K.; Ruther, Rose E.

Here, we created Immense Surface Area Carbons (ISACs) by a novel heat treatment that stabilized the micelle structure in a biological based precursor prior to high temperature combined activation – pyrolysis. While displaying a morphology akin to that of commercial activated carbon, ISACs contain an unparalleled combination of electrochemically active surface area and pore volume (up to 4051 m 2 g –1, total pore volume 2.60 cm 3 g –1, 76% small mesopores). The carbons also possess the benefit of being quite pure (combined O and N: 2.6–4.1 at%), thus allowing for a capacitive response that is primarily EDLC. Testedmore » at commercial mass loadings (~10 mg cm –2) ISACs demonstrate exceptional specific capacitance values throughout the entire relevant current density regime, with superior rate capability primarily due to the large fraction of mesopores. In the optimized ISAC, the specific capacitance ( C g) is 540 F g –1 at 0.2 A g –1, 409 F g –1 at 1 A g –1 and 226 F g –1 at a very high current density of 300 A g –1 (~0.15 second charge time). At intermediate and high currents, such capacitance values have not been previously reported for any carbon. Tested with a stable 1.8 V window in a 1 M Li 2SO 4 electrolyte, a symmetric supercapacitor cell yields a flat energy–power profile that is fully competitive with those of organic electrolyte systems: 29 W h kg –1 at 442 W kg –1 and 17 W h kg –1 at 3940 W kg –1. The cyclability of symmetric ISAC cells is also exceptional due to the minimization of faradaic reactions on the carbon surface, with 80% capacitance retention over 100 000 cycles in 1 M Li 2SO 4 and 75 000 cycles in 6 M KOH.« less

Unrivaled combination of surface area and pore volume in micelle-templated carbon for supercapacitor energy storage

DOE PAGES

Pokrzywinski, Jesse; Keum, Jong K.; Ruther, Rose E.; ...

2017-05-23

Here, we created Immense Surface Area Carbons (ISACs) by a novel heat treatment that stabilized the micelle structure in a biological based precursor prior to high temperature combined activation – pyrolysis. While displaying a morphology akin to that of commercial activated carbon, ISACs contain an unparalleled combination of electrochemically active surface area and pore volume (up to 4051 m 2 g –1, total pore volume 2.60 cm 3 g –1, 76% small mesopores). The carbons also possess the benefit of being quite pure (combined O and N: 2.6–4.1 at%), thus allowing for a capacitive response that is primarily EDLC. Testedmore » at commercial mass loadings (~10 mg cm –2) ISACs demonstrate exceptional specific capacitance values throughout the entire relevant current density regime, with superior rate capability primarily due to the large fraction of mesopores. In the optimized ISAC, the specific capacitance ( C g) is 540 F g –1 at 0.2 A g –1, 409 F g –1 at 1 A g –1 and 226 F g –1 at a very high current density of 300 A g –1 (~0.15 second charge time). At intermediate and high currents, such capacitance values have not been previously reported for any carbon. Tested with a stable 1.8 V window in a 1 M Li 2SO 4 electrolyte, a symmetric supercapacitor cell yields a flat energy–power profile that is fully competitive with those of organic electrolyte systems: 29 W h kg –1 at 442 W kg –1 and 17 W h kg –1 at 3940 W kg –1. The cyclability of symmetric ISAC cells is also exceptional due to the minimization of faradaic reactions on the carbon surface, with 80% capacitance retention over 100 000 cycles in 1 M Li 2SO 4 and 75 000 cycles in 6 M KOH.« less

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

NASA Astrophysics Data System (ADS)

Beckingham, Lauren E.; Steefel, Carl I.; Swift, Alexander M.; Voltolini, Marco; Yang, Li; Anovitz, Lawrence M.; Sheets, Julia M.; Cole, David R.; Kneafsey, Timothy J.; Mitnick, Elizabeth H.; Zhang, Shuo; Landrot, Gautier; Ajo-Franklin, Jonathan B.; DePaolo, Donald J.; Mito, Saeko; Xue, Ziqiu

2017-05-01

The rates of mineral dissolution reactions in porous media are difficult to predict, in part because of a lack of understanding of mineral reactive surface area in natural porous media. Common estimates of mineral reactive surface area used in reactive transport models for porous media are typically ad hoc and often based on average grain size, increased to account for surface roughness or decreased by several orders of magnitude to account for reduced surface reactivity of field as opposed to laboratory samples. In this study, accessible mineral surface areas are determined for a sample from the reservoir formation at the Nagaoka pilot CO2 injection site (Japan) using a multi-scale image analysis based on synchrotron X-ray microCT, SEM QEMSCAN, XRD, SANS, and FIB-SEM. This analysis not only accounts for accessibility of mineral surfaces to macro-pores, but also accessibility through connected micro-pores in smectite, the most abundant clay mineral in this sample. While the imaging analysis reveals that most of the micro- and macro-pores are well connected, some pore regions are unconnected and thus inaccessible to fluid flow and diffusion. To evaluate whether mineral accessible surface area accurately reflects reactive surface area a flow-through core experiment is performed and modeled at the continuum scale. The core experiment is performed under conditions replicating the pilot site and the evolution of effluent solutes in the aqueous phase is tracked. Various reactive surface area models are evaluated for their ability to capture the observed effluent chemistry, beginning with parameter values determined as a best fit to a disaggregated sediment experiment (Beckingham et al., 2016) described previously. Simulations that assume that all mineral surfaces are accessible (as in the disaggregated sediment experiment) over-predict the observed mineral reaction rates, suggesting that a reduction of RSA by a factor of 10-20 is required to match the core flood

A Mathematical Method to Calculate Tumor Contact Surface Area: An Effective Parameter to Predict Renal Function after Partial Nephrectomy.

PubMed

Hsieh, Po-Fan; Wang, Yu-De; Huang, Chi-Ping; Wu, Hsi-Chin; Yang, Che-Rei; Chen, Guang-Heng; Chang, Chao-Hsiang

2016-07-01

We proposed a mathematical formula to calculate contact surface area between a tumor and renal parenchyma. We examined the applicability of using contact surface area to predict renal function after partial nephrectomy. We performed this retrospective study in patients who underwent partial nephrectomy between January 2012 and December 2014. Based on abdominopelvic computerized tomography or magnetic resonance imaging, we calculated the contact surface area using the formula (2*π*radius*depth) developed by integral calculus. We then evaluated the correlation between contact surface area and perioperative parameters, and compared contact surface area and R.E.N.A.L. (Radius/Exophytic/endophytic/Nearness to collecting system/Anterior/Location) score in predicting a reduction in renal function. Overall 35, 26 and 45 patients underwent partial nephrectomy with open, laparoscopic and robotic approaches, respectively. Mean ± SD contact surface area was 30.7±26.1 cm(2) and median (IQR) R.E.N.A.L. score was 7 (2.25). Spearman correlation analysis showed that contact surface area was significantly associated with estimated blood loss (p=0.04), operative time (p=0.04) and percent change in estimated glomerular filtration rate (p <0.001). On multivariate analysis contact surface area and R.E.N.A.L. score independently affected percent change in estimated glomerular filtration rate (p <0.001 and p=0.03, respectively). On ROC curve analysis contact surface area was a better independent predictor of a greater than 10% change in estimated glomerular filtration rate compared to R.E.N.A.L. score (AUC 0.86 vs 0.69). Using this simple mathematical method, contact surface area was associated with surgical outcomes. Compared to R.E.N.A.L. score, contact surface area was a better predictor of functional change after partial nephrectomy. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Proton exchange membrane and electrode surface areas as factors that affect power generation in microbial fuel cells.

PubMed

Oh, Sang-Eun; Logan, Bruce E

2006-03-01

Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered MFCs having PEMs with three different surface areas (A (PEM)=3.5, 6.2, or 30.6 cm(2)). For a fixed anode and cathode surface area (A (An)=A (Cat)=22.5 cm(2)), the power density normalized to the anode surface area increased with the PEM size in the order 45 mW/m(2) (A (PEM)=3.5 cm(2)), 68 mW/m(2) (A (PEM)=6.2 cm(2)), and 190 mW/m(2) (A (PEM)=30.6 cm(2)). PEM surface area was shown to limit power output when the surface area of the PEM was smaller than that of the electrodes due to an increase in internal resistance. When the relative cross sections of the PEM, anode, and cathode were scaled according to 2A (Cat)=A(PEM)=2A (An), the maximum power densities of the three different MFCs, based on the surface area of the PEM (A (PEM)=3.5, 6.2, or 30.6 cm(2)), were the same (168+/-4.53 mW/m(2)). Increasing the ionic strength and using ferricyanide at the cathode also increased power output.

Learning about Surface Area through a Digital Fabrication-Augmented Unit

ERIC Educational Resources Information Center

Corum, Kimberly; Garofalo, Joe

2016-01-01

Surface area is consistently identified as a curriculum standard for K-12 students and it regularly appears on national and international assessments. Recently, many schools began acquiring digital fabrication and advanced manufacturing equipment. The growing use of digital fabrication in classrooms raises the question of whether or not this…

Inter-species activity correlations reveal functional correspondences between monkey and human brain areas

PubMed Central

Mantini, Dante; Hasson, Uri; Betti, Viviana; Perrucci, Mauro G.; Romani, Gian Luca; Corbetta, Maurizio; Orban, Guy A.; Vanduffel, Wim

2012-01-01

Evolution-driven functional changes in the primate brain are typically assessed by aligning monkey and human activation maps using cortical surface expansion models. These models use putative homologous areas as registration landmarks, assuming they are functionally correspondent. In cases where functional changes have occurred in an area, this assumption prohibits to reveal whether other areas may have assumed lost functions. Here we describe a method to examine functional correspondences across species. Without making spatial assumptions, we assess similarities in sensory-driven functional magnetic resonance imaging responses between monkey (Macaca mulatta) and human brain areas by means of temporal correlation. Using natural vision data, we reveal regions for which functional processing has shifted to topologically divergent locations during evolution. We conclude that substantial evolution-driven functional reorganizations have occurred, not always consistent with cortical expansion processes. This novel framework for evaluating changes in functional architecture is crucial to building more accurate evolutionary models. PMID:22306809

Surface active properties of lipid nanocapsules.

PubMed

Mouzouvi, Celia R A; Umerska, Anita; Bigot, André K; Saulnier, Patrick

2017-01-01

Lipid nanocapsules (LNCs) are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS) and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs' properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8-35.0 mN/m and 37.7-38.8 mN/m, respectively), as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC) that was 10-fold higher than the critical micellar concentration (CMC) of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications.

Active micromixer using surface acoustic wave streaming

DOEpatents

Branch,; Darren W. , Meyer; Grant D. , Craighead; Harold, G [Ithaca, NY

2011-05-17

An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

Is the planum temporale surface area a marker of hemispheric or regional language lateralization?

PubMed

Tzourio-Mazoyer, Nathalie; Crivello, Fabrice; Mazoyer, Bernard

2018-04-01

We investigated the association between the left planum temporale (PT) surface area or asymmetry and the hemispheric or regional functional asymmetries during language production and perception tasks in 287 healthy adults (BIL&GIN) who were matched for sex and handedness. The measurements of the PT surface area were performed after manually delineating the region using brain magnetic resonance images (MRI) and considering the Heschl's gyrus (HG) duplication pattern; the measurements either included (PT tot ) or did not include (PT post ) the second gyrus. A region encompassing both the PT and HG (HGPT) was also studied. Regardless of the ROI measured, 80% of the sample had a positive left minus right PT asymmetry. We first tested whether the PT tot , PT post and HGPT surface areas in the left or right hemispheres or PT asymmetries differed in groups of individuals varying in language lateralization by assessing their hemispheric index during a sentence production minus word list production task. We then investigated the association between these different measures of the PT anatomy and the regional asymmetries measured during the task. Regardless of the anatomical definition used, we observed no correlations between the left surface areas or asymmetries and the hemispheric or regional functional asymmetries during the language production task. We then performed a similar analysis using the same sample measuring language functional lateralization during speech listening tasks (i.e., listening to sentences and lists of words). Although the hemispheric lateralization during speech listening was not correlated with the left PT tot , PT post or HGPT surface areas or the PT asymmetries, significant positive correlations were observed between the asymmetries in these regions and the regional functional asymmetries measured in areas adjacent to the end of the Sylvian fissure while participants listened to the word lists or sentences. The PT asymmetry thus appears to be

36 CFR 294.25 - Mineral activities in Idaho Roadless Areas.

Code of Federal Regulations, 2010 CFR

2010-07-01

... recommend, authorize, or consent to road construction, road reconstruction, or surface occupancy associated... construction or road reconstruction associated with mineral leases in Idaho Roadless Areas designated as Backcountry/Restoration. Surface use or occupancy without road construction or reconstruction is permissible...

Active colloidal propulsion over a crystalline surface

NASA Astrophysics Data System (ADS)

Choudhury, Udit; Straube, Arthur V.; Fischer, Peer; Gibbs, John G.; Höfling, Felix

2017-12-01

We study both experimentally and theoretically the dynamics of chemically self-propelled Janus colloids moving atop a two-dimensional crystalline surface. The surface is a hexagonally close-packed monolayer of colloidal particles of the same size as the mobile one. The dynamics of the self-propelled colloid reflects the competition between hindered diffusion due to the periodic surface and enhanced diffusion due to active motion. Which contribution dominates depends on the propulsion strength, which can be systematically tuned by changing the concentration of a chemical fuel. The mean-square displacements (MSDs) obtained from the experiment exhibit enhanced diffusion at long lag times. Our experimental data are consistent with a Langevin model for the effectively two-dimensional translational motion of an active Brownian particle in a periodic potential, combining the confining effects of gravity and the crystalline surface with the free rotational diffusion of the colloid. Approximate analytical predictions are made for the MSD describing the crossover from free Brownian motion at short times to active diffusion at long times. The results are in semi-quantitative agreement with numerical results of a refined Langevin model that treats translational and rotational degrees of freedom on the same footing.

Geology and surface geochemistry of the Roosevelt Springs Known Geothermal Resource Area, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovell, J.S.; Meyer, W.T.; Atkinson, D.J.

1980-01-01

Available data on the Roosevelt area were synthesized to determine the spatial arrangement of the rocks, and the patterns of mass and energy flow within them. The resulting model lead to a new interpretation of the geothermal system, and provided ground truth for evaluating the application of soil geochemistry to exploration for concealed geothermal fields. Preliminary geochemical studies comparing the surface microlayer to conventional soil sampling methods indicated both practical and chemical advantages for the surface microlayer technique, which was particularly evident in the case of As, Sb and Cs. Subsequent multi-element analyses of surface microlayer samples collected over anmore » area of 100 square miles were processed to produce single element contour maps for 41 chemical parameters. Computer manipulation of the multi-element data using R-mode factor analysis provided the optimum method of interpretation of the surface microlayer data. A trace element association of As, Sb and Cs in the surface microlayer provided the best indication of the leakage of geothermal solutions to the surface, while regional mercury trends may reflect the presence of a mercury vapour anomaly above a concealed heat source.« less

In-use catalyst surface area and its relation to HC conversion efficiency and FTP emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donahue, K.S.; Sabourin, M.A.; Larson, R.E.

1986-01-01

Surface area data, steady-state hydrocarbon conversion efficiency data, and hydrocarbon emissions results have been determined for catalysts collected by the U.S. Environmental Protection Agency from properly maintained 1981 and 1982 model year vehicles. Catalysts covered in this study were limited to those with three-way-plus-oxidation monolith technologies. Catalyst surface areas were measured using the BET method, conversion efficiencies were measured on an exhaust gas generator, and emissions results were determined using the Urban Driving Schedule of the Federal Test Procedure. Results indicate that correlation of catalyst surface area data with hydrocarbon conversion efficiency data and hydrocarbon emissions results is significant formore » the sample studied.« less

Occurrence and sources of natural and anthropogenic lipid tracers in surface soils from arid urban areas of Saudi Arabia.

PubMed

Rushdi, Ahmed I; Al-Mutlaq, Khalid F; El-Mubarak, Aarif H; Al-Saleh, Mohammed A; El-Otaibi, Mubarak T; Ibrahim, Sami M M; Simoneit, Bernd R T

2016-01-01

Soil particles contain a variety of natural and anthropogenic organic components, and in urban areas can be considered as local collectors of pollutants. Surface soil samples were taken from ten urban areas in Riyadh during early winter of 2007. They were extracted with dichloromethane-methanol mixture and the extracts were analyzed by gas chromatography-mass spectrometry. The major compounds were unresolved complex mixture (UCM), plasticizers, n-alkanes, carbohydrates, n-alkanoic acids, hopanes, n-alkanols, and sterols. Vegetation detritus was the major natural source of organic compounds (24.0 ± 15.7%) in samples from areas with less human activities and included n-alkanes, n-alkanoic acids, n-alkanols, sterols and carbohydrates. Vehicular emission products and discarded plastics were the major anthropogenic sources in the soil particles (53.3 ± 21.3% and 22.7 ± 10.7%, respectively). The anthropogenic tracers were UCM, plasticizers, n-alkanes, hopanes and traces of steranes. Vegetation and human activities control the occurrence and distribution of natural and anthropogenic extractable organic matter in this arid urban area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Human hair-derived high surface area porous carbon material for the adsorption isotherm and kinetics of tetracycline antibiotics.

PubMed

Ahmed, M J; Islam, Md Azharul; Asif, M; Hameed, B H

2017-11-01

In this work, a human hair-derived high surface area porous carbon material (HHC) was prepared using potassium hydroxide activation. The morphology and textural properties of the HHC structure, along with its adsorption performance for tetracycline (TC) antibiotics, were evaluated. HHC showed a high surface area of 1505.11m 2 /g and 68.34% microporosity. The effects of most important variables, such as initial concentration (25-355mg/L), solution pH (3-13), and temperatures (30-50°C), on the HHC adsorption performance were investigated. Isotherm data analysis revealed the favorable application of the Langmuir model, with maximum TC uptakes of 128.52, 162.62, and 210.18mg/g at 30, 40, and 50°C, respectively. The experimental data of TC uptakes versus time were analyzed efficiently using a pseudo-first order model. Porous HHC could be an efficient adsorbent for eliminating antibiotic pollutants in wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen-doped hierarchical porous carbon with high surface area derived from graphene oxide/pitch oxide composite for supercapacitors.

PubMed

Ma, Yuan; Ma, Chang; Sheng, Jie; Zhang, Haixia; Wang, Ranran; Xie, Zhenyu; Shi, Jingli

2016-01-01

A nitrogen-doped hierarchical porous carbon has been prepared through one-step KOH activation of pitch oxide/graphene oxide composite. At a low weight ratio of KOH/composite (1:1), the as-prepared carbon possesses high specific surface area, rich nitrogen and oxygen, appropriate mesopore/micropore ratio and considerable small-sized mesopores. The addition of graphene oxide plays a key role in forming 4 nm mesopores. The sample PO-GO-16 presents the characteristics of large surface area (2196 m(2) g(-1)), high mesoporosity (47.6%), as well as rich nitrogen (1.52 at.%) and oxygen (6.9 at.%). As a result, PO-GO-16 electrode shows an outstanding capacitive behavior: high capacitance (296 F g(-1)) and ultrahigh-rate performance (192 F g(-1) at 10 A g(-1)) in 6 M KOH aqueous electrolyte. The balanced structure characteristic, low-cost and high performance, make the porous carbon a promising electrode material for supercapacitors. Copyright © 2015 Elsevier Inc. All rights reserved.

Aerosol Optical Depth Retrievals From High-Resolution Commercial Satellite Imagery Over Areas of High Surface Reflectance

NASA Astrophysics Data System (ADS)

Vincent, D. A.; Nielsen, K. E.; Durkee, P. A.; Reid, J. S.

2005-12-01

The advancement and proliferation of high-resolution commercial imaging satellites presents a new opportunity for overland aerosol characterization. Current aerosol optical depth retrieval methods typically fail over areas with high surface reflectance, such as urban areas and deserts, since the upwelling radiance due to scattering by aerosols is small compared to the radiance resulting from surface reflection. The method proposed here uses shadows cast on the surface to exploit the differences between radiance from the adjacent shaded and unshaded areas of the scene. Shaded areas of the scene are primarily illuminated by diffuse irradiance that is scattered downward from the atmosphere, while unshaded areas are illuminated by both diffuse and direct solar irradiance. The first-order difference between the shaded and unshaded areas is the direct component. Given uniform surface reflectance for the shaded and unshaded areas, the difference in reflected radiance measured by a satellite sensor is related to the direct transmission of solar radiation and inversely proportional to total optical depth. Using an iterative approach, surface reflectance and mean aerosol reflectance can be partitioned to refine the retrieved total optical depth. Aerosol optical depth can then be determined from its contribution to the total atmospheric optical depth (following correction for molecular Rayleigh scattering). Intitial results based on QuickBird imagery and AERONET data collected during the United Arab Emirates Unified Aerosol Experiment (UAE2) indicate that aerosol optical depth retrievals are possible in the visible and near-infrared region with an accuracy of ~0.04.

Correlation of Superior Canal Dehiscence Surface Area With Vestibular Evoked Myogenic Potentials, Audiometric Thresholds, and Dizziness Handicap.

PubMed

Hunter, Jacob B; O'Connell, Brendan P; Wang, Jianing; Chakravorti, Srijata; Makowiec, Katie; Carlson, Matthew L; Dawant, Benoit; McCaslin, Devin L; Noble, Jack H; Wanna, George B

2016-09-01

To correlate objective measures of vestibular and audiometric function as well as subjective measures of dizziness handicap with the surface area of the superior canal dehiscence (SCD). Retrospective chart review and radiological analysis. Single tertiary academic referral center. Preoperative computed tomography imaging, patient survey, audiometric thresholds, and vestibular evoked myogenic potential (VEMP) testing in patients with confirmed SCD. Image analysis techniques were developed to measure the surface area of each SCD in computed tomography imaging. Preoperative ocular and cervical VEMPs, air and bone conduction thresholds, air-bone gap, dizziness handicap inventory scores, and surface area of the SCD. Fifty-three patients (mean age 52.7 yr) with 84 SCD were analyzed. The median surface area of dehiscence was 1.44 mm (0.068-8.23 mm). Ocular VEMP amplitudes (r = 0.61, p <0.0001), cervical VEMP amplitudes (r = 0.62, p <0.0001), air conduction thresholds at 250 Hz (r = 0.25, p = 0.043), and air-bone gap at 500 Hz (r = 0.27, p = 0.01) positively correlated with increasing size of dehiscence. An inverse relationship between cervical VEMP thresholds (r = -0.56, p < 0.0001) and surface area of the dehiscence was observed. No association between dizziness handicap and surface area was identified. Among patients with confirmed SCD, ocular and cervical VEMP amplitudes, cervical VEMP thresholds, and air conduction thresholds at 250 Hz are significantly correlated with the surface area of the dehiscence.

The detection of intestinal spike activity on surface electroenterograms

NASA Astrophysics Data System (ADS)

Ye-Lin, Y.; Garcia-Casado, J.; Martinez-de-Juan, J. L.; Prats-Boluda, G.; Ponce, J. L.

2010-02-01

Myoelectrical recording could provide an alternative technique for assessing intestinal motility, which is a topic of great interest in gastroenterology since many gastrointestinal disorders are associated with intestinal dysmotility. The pacemaker activity (slow wave, SW) of the electroenterogram (EEnG) has been detected in abdominal surface recordings, although the activity related to bowel contractions (spike bursts, SB) has to date only been detected in experimental models with artificially favored electrical conductivity. The aim of the present work was to assess the possibility of detecting SB activity in abdominal surface recordings under physiological conditions. For this purpose, 11 recording sessions of simultaneous internal and external myolectrical signals were conducted on conscious dogs. Signal analysis was carried out in the spectral domain. The results show that in periods of intestinal contractile activity, high-frequency components of EEnG signals can be detected on the abdominal surface in addition to SW activity. The energy between 2 and 20 Hz of the surface myoelectrical recording presented good correlation with the internal intestinal motility index (0.64 ± 0.10 for channel 1 and 0.57 ± 0.11 for channel 2). This suggests that SB activity can also be detected in canine surface EEnG recording.

Adsorption of cationic surfactants on covered hanging mercury drop electrode surface of variable area.

PubMed

Koniari, Argyri; Avranas, Antonis

2012-09-15

Cetyldimethylbenzylammonium chloride (CDBACl) or cetyltrimethylammonium bromide (CTAB) is preadsorbed on mercury and used as substrate. The adsorptive stripping voltammetry with the two-step procedure is used. The mercury droplet with the preadsorbed surfactant is expanded in aqueous solutions of KCl, KBr, CTAB, CDBACl, or cetylethyldimethylammonium bromide (CEDAB). The surface area was increased from 0.0022cm(2) up to 0.0571cm(2). The surfactant molecules are maintained close to each other and in the vicinity of the electrode by the applied electric field. The expanding of the droplets resulted in a reorientation of the adsorbed molecules depending on the surfactant surface concentration. In some cases, condensed films were observed. Differences were noticed in the adsorption and desorption potential region. A linear increase in the capacitance current with the surface area was found in all cases up to a maximum increase in the surface area. Partly disorganized films were also observed. In some cases, defects were noticed during expansion. In one case, fractal structure was observed. Copyright © 2012 Elsevier Inc. All rights reserved.

Surface water areas significantly impacted 2014 dengue outbreaks in Guangzhou, China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Huaiyu; Huang, Shanqian

Dengue transmission in urban areas is strongly influenced by a range of biological and environmental factors, yet the key drivers still need further exploration. To better understand mechanisms of environment–mosquito–urban dengue transmission, we propose an empirical model parameterized and cross-validated from a unique dataset including viral gene sequences, vector dynamics and human dengue cases in Guangzhou, China, together with a 36-year urban environmental change maps investigated by spatiotemporal satellite image fusion. The dengue epidemics in Guangzhou are highly episodic and were not associated with annual rainfall over time. Our results indicate that urban environmental changes, especially variations in surface areamore » covered by water in urban areas, can substantially alter the virus population and dengue transmission. The recent severe dengue outbreaks in Guangzhou may be due to the surge in an artificial lake construction, which could increase infection force between vector (mainly Aedes albopictus) and host when urban water area significantly increased. Impacts of urban environmental change on dengue dynamics may not have been thoroughly investigated in the past studies and more work needs to be done to better understand the consequences of urbanization processes in our changing world. - Highlights: • Urban dengue outbreak is associated with water area in Guangzhou, 1978–2014. • Surface water area can alter population size of dengue virus in urban area. • Urban dengue outbreak is not associated with annual rainfall in Guangzhou. • Spatiotemporal satellite image fusion can investigate urban environmental change. • Urban environmental change could induce virus, vector, and dengue epidemic change.« less

Understanding the effect of surface/bulk defects on the photocatalytic activity of TiO2: anatase versus rutile.

PubMed

Yan, Junqing; Wu, Guangjun; Guan, Naijia; Li, Landong; Li, Zhuoxin; Cao, Xingzhong

2013-07-14

The sole effect of surface/bulk defects of TiO2 samples on their photocatalytic activity was investigated. Nano-sized anatase and rutile TiO2 were prepared by hydrothermal method and their surface/bulk defects were adjusted simply by calcination at different temperatures, i.e. 400-700 °C. High temperature calcinations induced the growth of crystalline sizes and a decrease in the surface areas, while the crystalline phase and the exposed facets were kept unchanged during calcination, as indicated by the characterization results from XRD, Raman, nitrogen adsorption-desorption, TEM and UV-Vis spectra. The existence of surface/bulk defects in calcined TiO2 samples was confirmed by photoluminescence and XPS spectra, and the surface/bulk defect ratio was quantitatively analyzed according to positron annihilation results. The photocatalytic activity of calcined TiO2 samples was evaluated in the photocatalytic reforming of methanol and the photocatalytic oxidation of α-phenethyl alcohol. Based on the characterization and catalytic results, a direct correlation between the surface specific photocatalytic activity and the surface/bulk defect density ratio could be drawn for both anatase TiO2 and rutile TiO2. The surface defects of TiO2, i.e. oxygen vacancy clusters, could promote the separation of electron-hole pairs under irradiation, and therefore, enhance the activity during photocatalytic reaction.

Target Surface Area Effects on Hot Electron Dynamics from High Intensity Laser-Plasma Interactions

DTIC Science & Technology

2016-08-19

New J. Phys. 18 (2016) 063020 doi:10.1088/1367-2630/18/6/063020 PAPER Target surface area effects on hot electron dynamics from high intensity laser ...Science, University ofMichigan, AnnArbor,MI 48109-2099, USA E-mail: czulick@umich.edu Keywords: laser -plasma,mass-limited, fast electrons, sheath...field Abstract Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron

Ground-water and surface-water elevations in the Fairbanks International Airport area, Alaska, 1990-94

USGS Publications Warehouse

Claar, D.V.; Lilly, M.R.

1995-01-01

Ground-water and surface-water elevation data were collected at 52 sites from 1990 to 1994 by the U.S. Geological Survey in cooperation with the Alaska Department of Transportation and Public Facilities, Fairbanks International Airport. Water elevations were measured in 32 ground-water observation wells and at 20 surface-water sites to help characterize the geohydrology of the Fairbanks International Airport area. From 1990 to 1993, data were collected in the vicinity of the former fire-training area at the airport. From 1993 to 1994, the data-collection area was expanded to include the entire airport area.

Sterols as biomarkers in the surface microlayer of the estuarine areas.

PubMed

Alsalahi, Murad Ali; Latif, Mohd Talib; Ali, Masni Mohd; Dominick, Doreena; Khan, Md Firoz; Mustaffa, Nur Ili Hamizah; Nadzir, Mohd Shahrul Mohd; Nasher, Essam; Zakaria, Mohamad Pauzi

2015-04-15

This study aims to determine the concentration of sterols used as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. Samples were collected during different seasons through the use of a rotation drum. The analysis of sterols was performed using gas chromatography equipped with a flame ionisation detector (GC-FID). The results showed that the concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L(-1). The total sterol concentration was found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%). Copyright © 2015 Elsevier Ltd. All rights reserved.

Surface models for coupled modelling of runoff and sewer flow in urban areas.

PubMed

Ettrich, N; Steiner, K; Thomas, M; Rothe, R

2005-01-01

Traditional methods fail for the purpose of simulating the complete flow process in urban areas as a consequence of heavy rainfall and as required by the European Standard EN-752 since the bi-directional coupling between sewer and surface is not properly handled. The new methodology, developed in the EUREKA-project RisUrSim, solves this problem by carrying out the runoff on the basis of shallow water equations solved on high-resolution surface grids. Exchange nodes between the sewer and the surface, like inlets and manholes, are located in the computational grid and water leaving the sewer in case of surcharge is further distributed on the surface. Dense topographical information is needed to build a model suitable for hydrodynamic runoff calculations; in urban areas, in addition, many line-shaped elements like houses, curbs, etc. guide the runoff of water and require polygonal input. Airborne data collection methods offer a great chance to economically gather densely sampled input data.

Surface deformation monitoring of Sinabung volcano using multi temporal InSAR method and GIS analysis for affected area assessment

NASA Astrophysics Data System (ADS)

Aditiya, A.; Aoki, Y.; Anugrah, R. D.

2018-04-01

Sinabung Volcano which located in northern part of Sumatera island is part of a hundred active volcano in Indonesia. Surface deformation is detected over Sinabung Volcano and surrounded area since the first eruption in 2010 after 400 years long rest. We present multi temporal Interferometric Synthetic Aperture Radar (InSAR) time-series method of ALOS-2 L-band SAR data acquired from December 2014 to July 2017 to reveal surface deformation with high spatial resolution. The method includes focusing the SAR data, generating interferogram and phase unwrapping using SNAPHU tools. The result reveal significant deformation over Sinabung Volcano areas at rates up to 10 cm during observation period and the highest deformation occurs in western part which is trajectory of lava. We concluded the observed deformation primarily caused by volcanic activity respectively after long period of rest. In addition, Geographic Information System (GIS) analysis produces disaster affected areas of Sinabung eruption. GIS is reliable technique to estimate the impact of the hazard scenario to the exposure data and develop scenarios of disaster impacts to inform their contingency and emergency plan. The GIS results include the estimated affected area divided into 3 zones based on pyroclastic lava flow and pyroclastic fall (incandescent rock and ash). The highest impact is occurred in zone II due to many settlements are scattered in this zone. This information will be support stakeholders to take emergency preparation for disaster reduction. The continuation of this high rate of decline tends to endanger the population in next periods.

High surface area graphene-supported metal chalcogenide assembly

DOEpatents

Worsley, Marcus A.; Kuntz, Joshua; Orme, Christine A.

2016-04-19

A composition comprising at least one graphene-supported assembly, which comprises a three-dimensional network of graphene sheets crosslinked by covalent carbon bonds, and at least one metal chalcogenide compound disposed on said graphene sheets, wherein the chalcogen of said metal chalcogenide compound is selected from S, Se and Te. Also disclosed are methods for making and using the graphene-supported assembly, including graphene-supported MoS.sub.2. Monoliths with high surface area and conductivity can be achieved. Lower operating temperatures in some applications can be achieved. Pore size and volume can be tuned.

Comparison on surface properties and desulfurization of MnO2 and pyrolusite blended activated carbon by steam activation.

PubMed

Zhang, Guochen; Zhao, Xin; Ning, Ping; Yang, Danni; Jiang, Xia; Jiang, Wenju

2018-04-18

In this study, MnO 2 and pyrolusite were used as the catalysts to prepare modified activated carbon, i.e., AC-Mn and AC-P, respectively, from coals by blending method and steam activation. The BET results indicated that the AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The relative contents of basic functional groups (i.e. C = O, π-π*) on AC-P were slightly lower than those on AC-Mn, while both contained the same main metal species, i.e. MnO. The desulfurization results showed that with 3 wt% of blending ratio, AC-Mn3 and AC-P3 had higher sulfur capacities at 220 and 205 mg/g, respectively, which were much higher than blank one (149.6 mg/g). Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn, which might be attributed to the existence of other metals in pyrolusite. After desulfurization process, MnO were gradually transferred into MnSO 4 , and the relative contents of basic functional groups decreased evidently for both AC-Mn3 and AC-P3. The results demonstrated that pyrolusite could be one good alternative of MnO 2 to prepare modified activated carbon for desulfurization. Implication statement MnO 2 and pyrolusite were used as the additives to prepare the modified activated carbon from coals by blending method and steam activation, i.e., AC-Mn and AC-P, respectively. The AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The AC-Mn and AC-P had higher sulfur capacities than blank one. Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn. The results demonstrated that pyrolusite could be one good alternative of MnO 2 to prepare modified activated carbon for desulfurization.

The role of spatial integration in the perception of surface orientation with active touch.

PubMed

Giachritsis, Christos D; Wing, Alan M; Lovell, Paul G

2009-10-01

Vision research has shown that perception of line orientation, in the fovea area, improves with line length (Westheimer & Ley, 1997). This suggests that the visual system may use spatial integration to improve perception of orientation. In the present experiments, we investigated the role of spatial integration in the perception of surface orientation using kinesthetic and proprioceptive information from shoulder and elbow. With their left index fingers, participants actively explored virtual slanted surfaces of different lengths and orientations, and were asked to reproduce an orientation or discriminate between two orientations. Results showed that reproduction errors and discrimination thresholds improve with surface length. This suggests that the proprioceptive shoulder-elbow system may integrate redundant spatial information resulting from extended arm movements to improve orientation judgments.

Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes.

PubMed

Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

2016-07-28

In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication.

Perspective of surface active agents in baking industry: an overview.

PubMed

Ahmad, Asif; Arshad, Nazish; Ahmed, Zaheer; Bhatti, Muhammad Shahbaz; Zahoor, Tahir; Anjum, Nomana; Ahmad, Hajra; Afreen, Asma

2014-01-01

Different researchers have previously used surfactants for improving bread qualities and revealed that these compounds result in improving the quality of dough and bread by influencing dough strength, tolerance, uniform crumb cell size, and improve slicing characteristics and gas retention. The objective of this review is to highlight the areas where surfactants are most widely used particularly in the bread industries, their role and mechanism of interaction and their contribution to the quality characteristics of the dough and bread. This review reveals some aspects of surface-active agents regarding its role physiochemical properties of dough that in turn affect the bread characteristics by improving its sensory quality and storage stability.

Surface active properties of lipid nanocapsules

PubMed Central

Mouzouvi, Celia R. A.; Bigot, André K.; Saulnier, Patrick

2017-01-01

Lipid nanocapsules (LNCs) are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS) and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs’ properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8–35.0 mN/m and 37.7–38.8 mN/m, respectively), as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC) that was 10-fold higher than the critical micellar concentration (CMC) of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications. PMID:28796777

High-energy supercapacitors based on hierarchical porous carbon with an ultrahigh ion-accessible surface area in ionic liquid electrolytes.

PubMed

Zhong, Hui; Xu, Fei; Li, Zenghui; Fu, Ruowen; Wu, Dingcai

2013-06-07

A very important yet really challenging issue to address is how to greatly increase the energy density of supercapacitors to approach or even exceed those of batteries without sacrificing the power density. Herein we report the fabrication of a new class of ultrahigh surface area hierarchical porous carbon (UHSA-HPC) based on the pore formation and widening of polystyrene-derived HPC by KOH activation, and highlight its superior ability for energy storage in supercapacitors with ionic liquid (IL) as electrolyte. The UHSA-HPC with a surface area of more than 3000 m(2) g(-1) shows an extremely high energy density, i.e., 118 W h kg(-1) at a power density of 100 W kg(-1). This is ascribed to its unique hierarchical nanonetwork structure with a large number of small-sized nanopores for IL storage and an ideal meso-/macroporous network for IL transfer.

Large-area homogeneous periodic surface structures generated on the surface of sputtered boron carbide thin films by femtosecond laser processing

NASA Astrophysics Data System (ADS)

Serra, R.; Oliveira, V.; Oliveira, J. C.; Kubart, T.; Vilar, R.; Cavaleiro, A.

2015-03-01

Amorphous and crystalline sputtered boron carbide thin films have a very high hardness even surpassing that of bulk crystalline boron carbide (≈41 GPa). However, magnetron sputtered B-C films have high friction coefficients (C.o.F) which limit their industrial application. Nanopatterning of materials surfaces has been proposed as a solution to decrease the C.o.F. The contact area of the nanopatterned surfaces is decreased due to the nanometre size of the asperities which results in a significant reduction of adhesion and friction. In the present work, the surface of amorphous and polycrystalline B-C thin films deposited by magnetron sputtering was nanopatterned using infrared femtosecond laser radiation. Successive parallel laser tracks 10 μm apart were overlapped in order to obtain a processed area of about 3 mm2. Sinusoidal-like undulations with the same spatial period as the laser tracks were formed on the surface of the amorphous boron carbide films after laser processing. The undulations amplitude increases with increasing laser fluence. The formation of undulations with a 10 μm period was also observed on the surface of the crystalline boron carbide film processed with a pulse energy of 72 μJ. The amplitude of the undulations is about 10 times higher than in the amorphous films processed at the same pulse energy due to the higher roughness of the films and consequent increase in laser radiation absorption. LIPSS formation on the surface of the films was achieved for the three B-C films under study. However, LIPSS are formed under different circumstances. Processing of the amorphous films at low fluence (72 μJ) results in LIPSS formation only on localized spots on the film surface. LIPSS formation was also observed on the top of the undulations formed after laser processing with 78 μJ of the amorphous film deposited at 800 °C. Finally, large-area homogeneous LIPSS coverage of the boron carbide crystalline films surface was achieved within a large range

Tropical cyclone rainfall area controlled by relative sea surface temperature

PubMed Central

Lin, Yanluan; Zhao, Ming; Zhang, Minghua

2015-01-01

Tropical cyclone rainfall rates have been projected to increase in a warmer climate. The area coverage of tropical cyclones influences their impact on human lives, yet little is known about how tropical cyclone rainfall area will change in the future. Here, using satellite data and global atmospheric model simulations, we show that tropical cyclone rainfall area is controlled primarily by its environmental sea surface temperature (SST) relative to the tropical mean SST (that is, the relative SST), while rainfall rate increases with increasing absolute SST. Our result is consistent with previous numerical simulations that indicated tight relationships between tropical cyclone size and mid-tropospheric relative humidity. Global statistics of tropical cyclone rainfall area are not expected to change markedly under a warmer climate provided that SST change is relatively uniform, implying that increases in total rainfall will be confined to similar size domains with higher rainfall rates. PMID:25761457

Protein Surface Structural Recognition in Inactive Areas: A New Immobilization Strategy for Acetylcholinesterase.

PubMed

Diao, Jianxiong; Yu, Xiaolu; Ma, Lin; Li, Yuanqing; Sun, Ying

2018-05-16

This work reported a new method of design for the immobilization of acetylcholinesterase (AChE) based on its molecular structure to improve its sensitivity and stability. The immobilization binding site on the surface of AChE was determined using MOLCAD's multi-channel functionality. Then, 11 molecules ((+)-catechin, (-)-epicatechin, (-)-gallocatechin, hesperetin, naringenin, quercetin, taxifolin, (-)-epicatechin gallate, flupirtine, atropine, and hyoscyamine) were selected from the ZINC database (about 50 000 molecules) as candidate affinity ligands for AChE. The fluorescence results showed that the binding constant K b between AChE and the ligands ranged from 0.01344 × 10 4 to 4.689 × 10 4 M -1 and there was one independent class of binding site for the ligands on AChE. The AChE-ligand binding free energy ranged from -12.14 to -26.65 kJ mol -1 . Naringenin, hesperetin, and quercetin were the three most potent immobilized affinity ligands. In addition, it was confirmed that the binding between the immobilized ligands only occurred at a single site, located in an inactive area on the surface of AChE, and did not affect the enzymatic activity as shown through a competition experiment and enzyme assay. This method based on protein surface structural recognition with high sensitivity and stability can be used as a generic approach for design of the enzyme immobilization and biosensor development.

Geohydrology and susceptibility of major aquifers to surface contamination in Alabama; area 12

USGS Publications Warehouse

Scott, J.C.; Cobb, R.H.

1988-01-01

This report delineates and describes the geohydrology and susceptibility of major aquifers to contamination in Coffee, Dale, Henry, Houston, and Geneva Counties, Alabama. The major aquifers are the Upper Floridan, Lisbon, Nanafalia-Clayton, and Providence-Ripley aquifers. Estimated groundwater withdrawals for public water supplies are about 42 million gal/day. Maximum withdrawals for irrigation are 15 to 20 million gal/day. Withdrawals for self-supplied industrial and domestic uses are estimated to be 3 and 2.5 million gal/day, respectively. Long-term withdrawals of water from the Nanafalia-Clayton aquifer have resulted in significant declines in the potentiometric surface in Coffee, Dale, and Houston Counties. Significant declines in the potentiometric surfaces of the other major aquifers are not apparent. Recharge areas for all major aquifers are susceptible to contamination, but the probability of contamination of the Lisbon, Nanafalia-Clayton, and Providence-Ripley aquifers is low because the recharge areas are remote from areas of withdrawal. The recharge area for the Floridan aquifer, which consists largely of flat, sandy farmland , coincides with the area of use. This area is highly susceptible to contamination from insecticides and herbicides. (USGS)

The relationship between epicuticular long-chained hydrocarbons and surface area - volume ratios in insects (Diptera, Hymenoptera, Lepidoptera)

PubMed Central

Brückner, Adrian; Heethoff, Michael; Blüthgen, Nico

2017-01-01

Long-chain cuticular hydrocarbons (CHCs) are common components of the epicuticle of terrestrial arthropods. CHC serve as a protective barrier against environmental influences but also act as semiochemicals in animal communication. Regarding the latter aspect, species- or intra-functional group specific CHCs composition and variation are relatively well studied. However, comparative knowledge about the relationship of CHC quantity and their relation to surface area—volume ratios in the context of water loss and protection is fragmentary. Hence, we aim to study the taxon-specific relationship of the CHC amount and surface-area to volume ratio related to their functional role (e.g. in water loss). We focused on flower visiting insects and analyzed the CHC amounts of three insect orders (Hymenoptera, Lepidoptera and Diptera) using gas chromatography—mass spectrometry (GC-MS). We included 113 species from two grassland plots, quantified their CHCs, and measured their body mass and surface area. We found differences in the surface area, CHCs per body mass and the CHC density (= amount of CHCs per surface area) across the three insect taxa. Especially the Hymenoptera had a higher CHC density compared to Diptera and Lepidoptera. CHC density could be explained by surface area-volume ratios in Hymenoptera but not in Diptera and Lepidoptera. Unexpectedly, CHC density decreased with increasing surface area—volume ratios. PMID:28384308

Active and Passive Remote Sensing Data Time Series for Flood Detection and Surface Water Mapping

NASA Astrophysics Data System (ADS)

Bioresita, Filsa; Puissant, Anne; Stumpf, André; Malet, Jean-Philippe

2017-04-01

As a consequence of environmental changes surface waters are undergoing changes in time and space. A better knowledge of the spatial and temporal distribution of surface waters resources becomes essential to support sustainable policies and development activities. Especially because surface waters, are not only a vital sweet water resource, but can also pose hazards to human settlements and infrastructures through flooding. Floods are a highly frequent disaster in the world and can caused huge material losses. Detecting and mapping their spatial distribution is fundamental to ascertain damages and for relief efforts. Spaceborne Synthetic Aperture Radar (SAR) is an effective way to monitor surface waters bodies over large areas since it provides excellent temporal coverage and, all-weather day-and-night imaging capabilities. However, emergent vegetation, trees, wind or flow turbulence can increase radar back-scatter returns and pose problems for the delineation of inundated areas. In such areas, passive remote sensing data can be used to identify vegetated areas and support the interpretation of SAR data. The availability of new Earth Observation products, for example Sentinel-1 (active) and Sentinel-2 (passive) imageries, with both high spatial and temporal resolution, have the potential to facilitate flood detection and monitoring of surface waters changes which are very dynamic in space and time. In this context, the research consists of two parts. In the first part, the objective is to propose generic and reproducible methodologies for the analysis of Sentinel-1 time series data for floods detection and surface waters mapping. The processing chain comprises a series of pre-processing steps and the statistical modeling of the pixel value distribution to produce probabilistic maps for the presence of surface waters. Images pre-processing for all Sentinel-1 images comprise the reduction SAR effect like orbit errors, speckle noise, and geometric effects. A modified

Study on surface morphology and physicochemical properties of raw and activated South African coal and coal fly ash

NASA Astrophysics Data System (ADS)

Mishra, S. B.; Langwenya, S. P.; Mamba, B. B.; Balakrishnan, M.

South African coal and coal fly ash were selected as the raw materials to be used for study of their morphology and physicochemical properties and their respective activated carbons for adsorption applications. Coal and fly ash were individually steam activated at a temperature range of 550-1000 °C for 1 h in a muffle furnace using cylindrical stainless steel containers. Scanning electron micrographs revealed a change in surface morphology with more mineral matter available on the surface of the coal particles due to increased devolatilization. However, in the case of fly ash, the macerals coalesced to form agglomerates and the presence of unburnt carbon constituted pores of diameter between 50 and 100 nm. The BET surface area of coal improved significantly from 5.31 to 52.12 m 2/g whereas in case of fly ash the surface area of the raw sample which was originally 0.59 m 2/g and upon activation increased only up to 2.04 m 2/g. The chemical composition of the fly ash confirmed that silica was the major component which was approximately 60% by weight fraction. The impact of this study was to highlight the importance of using raw materials such as coal and a waste product, in the form of coal ash, in order to produce affordable activated carbon that can be used in drinking water treatment. This would therefore ensure that the quality of water supplied to communities for drinking is not contaminated especially by toxic organic compounds.

Test-area surface tension calculation of the graphene-methane interface: Fluctuations and commensurability

NASA Astrophysics Data System (ADS)

d'Oliveira, H. D.; Davoy, X.; Arche, E.; Malfreyt, P.; Ghoufi, A.

2017-06-01

The surface tension (γ) of methane on a graphene monolayer is calculated by using the test-area approach. By using a united atom model to describe methane molecules, strong fluctuations of surface tension as a function of the surface area of the graphene are evidenced. In contrast with the liquid-vapor interfaces, the use of a larger cutoff does not fully erase the fluctuations in the surface tension. Counterintuitively, the description of methane and graphene from the Optimized Potentials for Liquid Simulations all-atom model and a flexible model, respectively, led to a lessening in the surface tension fluctuations. This result suggests that the origin of fluctuations in γ is due to a model-effect rather than size-effects. We show that the molecular origin of these fluctuations is the result of a commensurable organization between both graphene and methane. This commensurable structure can be avoided by describing methane and graphene from a flexible force field. Although differences in γ with respect to the model have been often reported, it is the first time that the model drastically affects the physics of a system.

External Validation of Contact Surface Area as a Predictor of Postoperative Renal Function in Patients Undergoing Partial Nephrectomy.

PubMed

Haifler, Miki; Ristau, Benjamin T; Higgins, Andrew M; Smaldone, Marc C; Kutikov, Alexander; Zisman, Amnon; Uzzo, Robert G

2017-09-20

We sought to externally validate a mathematical formula for tumor contact surface area as a predictor of postoperative renal function in patients undergoing partial nephrectomy for renal cell carcinoma. We queried a prospectively maintained kidney cancer database for patients who underwent partial nephrectomy between 2014 and 2016. Contact surface area was calculated using data obtained from preoperative cross-sectional imaging. The correlation between contact surface area and perioperative variables was examined. The correlation between postoperative renal functional outcomes, contact surface area and the R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines and tumor touches main renal artery or vein) nephrometry score was also assessed. A total of 257 patients who underwent partial nephrectomy had sufficient data to enter the study. Median contact surface area was 14.5 cm 2 (IQR 6.2-36) and the median nephrometry score was 9 (IQR 7-10). Spearman correlation analysis showed that contact surface area correlated with estimated blood loss (r s = 0.42, p <0.001), length of stay (r s = 0.18, p = 0.005), and percent and absolute change in the estimated glomerular filtration rate (r s = -0.77 and -0.78, respectively, each p <0.001). On multivariable analysis contact surface area and nephrometry score were independent predictors of the absolute change in the estimated glomerular filtration rate (each p <0.001). ROC curve analysis revealed that contact surface area was a better predictor of a greater than 20% postoperative decline in the estimated glomerular filtration rate compared with the nephrometry score (AUC 0.94 vs 0.80). Contact surface area correlated with the change in postoperative renal function after partial nephrectomy. It can be used in conjunction with the nephrometry score to counsel patients about the risk of renal functional decline after partial

Smart Pd Catalyst with Improved Thermal Stability Supported on High-Surface-Area LaFeO3 Prepared by Atomic Layer Deposition.

PubMed

Onn, Tzia Ming; Monai, Matteo; Dai, Sheng; Fonda, Emiliano; Montini, Tiziano; Pan, Xiaoqing; Graham, George W; Fornasiero, Paolo; Gorte, Raymond J

2018-04-11

The concept of self-regenerating or "smart" catalysts, developed to mitigate the problem of supported metal particle coarsening in high-temperature applications, involves redispersing large metal particles by incorporating them into a perovskite-structured support under oxidizing conditions and then exsolving them as small metal particles under reducing conditions. Unfortunately, the redispersion process does not appear to work in practice because the surface areas of the perovskite supports are too low and the diffusion lengths for the metal ions within the bulk perovskite too short. Here, we demonstrate reversible activation upon redox cycling for CH 4 oxidation and CO oxidation on Pd supported on high-surface-area LaFeO 3 , prepared as a thin conformal coating on a porous MgAl 2 O 4 support using atomic layer deposition. The LaFeO 3 film, less than 1.5 nm thick, was shown to be initially stable to at least 900 °C. The activated catalysts exhibit stable catalytic performance for methane oxidation after high-temperature treatment.

Surface engineering on CeO2 nanorods by chemical redox etching and their enhanced catalytic activity for CO oxidation

NASA Astrophysics Data System (ADS)

Gao, Wei; Zhang, Zhiyun; Li, Jing; Ma, Yuanyuan; Qu, Yongquan

2015-07-01

Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications. Electronic supplementary information (ESI) available: Diameter distributions of as-prepared and etched samples, optical images, specific catalytic data of CO oxidation and comparison of CO oxidation. See DOI: 10.1039/c5nr01846c

Assessment of anthropogenic inputs in the surface waters of the southern coastal area of Sfax during spring (Tunisia, Southern Mediterranean Sea).

PubMed

Drira, Zaher; Kmiha-Megdiche, Salma; Sahnoun, Houda; Hammami, Ahmed; Allouche, Noureddine; Tedetti, Marc; Ayadi, Habib

2016-03-15

The coastal marine area of Sfax (Tunisia), which is well-known for its high productivity and fisheries, is also subjected to anthropogenic inputs from diverse industrial, urban and agriculture activities. We investigated the spatial distribution of physical, chemical and biogeochemical parameters in the surface waters of the southern coastal area of Sfax. Pertinent tracers of anthropogenic inputs were identified. Twenty stations were sampled during March 2013 in the vicinity of the coastal areas reserved for waste discharge. Phosphogypsum wastes dumped close to the beaches were the main source of PO4(3-), Cl(-) and SO4(2-) in seawater. The high content in total polyphenolic compounds was due to the olive oil treatment waste water released from margins. These inorganic and organic inputs in the surface waters were associated with elevated COD. The BOD5/COD (<0.5) and COD/BOD5 (>3) ratios highlighted a chemical pollution with organic load of a low biodegradability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mass, surface area and number metrics in diesel occupational exposure assessment.

PubMed

Ramachandran, Gurumurthy; Paulsen, Dwane; Watts, Winthrop; Kittelson, David

2005-07-01

While diesel aerosol exposure assessment has traditionally been based on the mass concentration metric, recent studies have suggested that particle number and surface area concentrations may be more health-relevant. In this study, we evaluated the exposures of three occupational groups-bus drivers, parking garage attendants, and bus mechanics-using the mass concentration of elemental carbon (EC) as well as surface area and number concentrations. These occupational groups are exposed to mixtures of diesel and gasoline exhaust on a regular basis in various ratios. The three groups had significantly different exposures to workshift TWA EC with the highest levels observed in the bus garage mechanics and the lowest levels in the parking ramp booth attendants. In terms of surface area, parking ramp attendants had significantly greater exposures than bus garage mechanics, who in turn had significantly greater exposures than bus drivers. In terms of number concentrations, the exposures of garage mechanics exceeded those of ramp booth attendants by a factor of 5-6. Depending on the exposure metric chosen, the three occupational groups had quite different exposure rankings. This illustrates the importance of the choice of exposure metric in epidemiological studies. If these three occupational groups were part of an epidemiological study, depending on the metric used, they may or may not be part of the same similarly exposed group (SEG). The exposure rankings (e.g., low, medium, or high) of the three groups also changes with the metric used. If the incorrect metric is used, significant misclassification errors may occur.

Geomorphic evidence of active faults growth in the Norcia seismic area (central Apennines, Italy)

NASA Astrophysics Data System (ADS)

Materazzi, Marco; Aringoli, Domenico; Farabollini, Piero; Giacopetti, Marco; Pambianchi, Gilberto; Tondi, Emanuele; Troiani, Francesco

2016-04-01

Fault-growth by segment linkage is one of the fundamental processes controlling the evolution, in both time and the space, of fault systems. In fact, step-like trajectories shown by length-displacement diagrams for individual fault arrays suggest that the development of evolved structures result by the linkage of single fault segments. The type of interaction between faults and the rate at which faults reactivate not only control the long term tectonic evolution of an area, but also influence the seismic hazard, as earthquake recurrence intervals tend to decrease as fault slip rate increase. The use of Geomorphological investigations represents an important tool to constrain the latest history of active faults. In this case, attention has to be given to recognize morphostructural, historical, environmental features at the surface, since they record the long-term seismic behavior due to the fault growth processes (Tondi and Cello, 2003). The aim of this work is to investigate the long term morphotectonic evolution of a well know seismic area in the central Apennines: the Norcia intramontane basin (Aringoli et al., 2005). The activity of the Norcia seismic area is characterized by moderate events and by strong earthquakes with maximum intensities of X-XI degrees MCS and equivalent magnitudes around 6.5±7.0 (CPTI, 2004). Based on the morphostructural features as well as on the historical seismicity of the area, we may divide the Norcia seismic area into three minor basins roughly NW-SE oriented: the Preci sub-basin in the north; the S. Scolastica and the Castel S. Maria sub-basins in the south. The wider basin (S. Scolastica) is separated from the other two by ridges transversally oriented with respect the basins themselves; they are the geomorphological response to the tectonic deformation which characterizes the whole area. Other geomorphological evidences of tectonic activity are represented by deformation of old summit erosional surfaces, hydrographic network

Trend-surface analysis of the structure of the Ste. Genevieve limestone in the Effingham, Illinois, area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevenson, D.

1970-01-01

Recent studies of oil accumulations in the Ste. Genevieve Limestone Formation in Illinois demonstrate the usefulness of fitting third-order trend surfaces to structural data and analyzing the residuals calculated by subtracting the trend surface from the structure surface. Known oil pools are located in areas having positive residual values. This type of investigation, supplemented by conventional structural and stratigraphic studies, was performed on a 9-township (approx. 324 sq miles) area in Effingham and Shelby counties, Illinois. The known oil pools in the oolite and sandstone lenses of the Ste. Genevieve Formation lie within positive residuals resulting from the difference betweenmore » a third-order trend surface and the structural surface on top of the Ste. Genevieve. A composite map outlining areas where present anticlinal noses, sandstone lenses, and positive residuals lie in close proximity to each other is included in this report to indicate places where future exploration for Ste. Genevieve oil would have the greatest chance for success.« less

Correlation between Surface Tension and Water Activity in New Particle Formation

NASA Astrophysics Data System (ADS)

Daskalakis, E.; Salameh, A.

2016-12-01

The impact of aerosol properties on cloud dynamics and the radiative balance of the atmosphere relies on the parametrizations of cloud droplet formation. Such parametrization is based on equilibrium thermodynamics proposed by Köhler in 1936. There is considerable debate in the literature on the importance of factors like the surface tension depression or the water activity decrease for the correct parametrization. To gain fundamental insight into New Particle Formation (NPF), or Cloud Condensation Nuclei (CCN) activation one has to study microscopic properties of aqueous droplets, involving surface and bulk dynamics. The surface tension of droplets can be associated with the effects from Organic Matter (OM), whereas the static dielectric constant of water reflects the structure and dynamics of ions within solutions and can present a measure of water activity. In this study we employ Molecular Dynamics Simulations on aquatic droplets that contain surface active OM (acetaldehyde, methylglyoxal) and salts. We give insight into the dynamics of aquatic droplets with radials of 3.6nm at a level of detail that is not accessible experimentally (J. Phys. Chem. C 2016, 120:11508). We propose that as the surface tension of an aquatic droplet is decreased in the presence of surface-active OM, the water activity is affected as well. This is due to the fact that the water dipoles are oriented based on the salt morphology within the droplet. We suggest that the surface tension depression can be accompanied by the water activity change. This can be associated with the possible effects of surface-active species in terms of salt morphology transitions within an aerosol at the NPF and early particle growth time scales. Based on this study, surface-active OM seems important in controlling (a) the salt morphology transitions within a nucleus during NPF and particle growth and (b) a correlation between surface activity and water activity of ionic aquatic droplets. The latter

The Apparent Contact Angle and Wetted Area of Active Alloys on Silicon Carbide as a Function of the Temperature and the Surface Roughness: A Multivariate Approach

NASA Astrophysics Data System (ADS)

Tillmann, Wolfgang; Pfeiffer, Jan; Wojarski, Lukas

2015-08-01

Despite the broad field of applications for active filler alloys for brazing ceramics, as well as intense research work on the wetting and spreading behavior of these alloys on ceramic surfaces within the last decades, the manufactured joints still exhibit significant variations in their properties due to the high sensitivity of the alloys to changing brazing conditions. This increases the need for investigations of the wetting and spreading behavior of filler alloys with regard to the dominating influences combined with their interdependencies, instead of solely focusing on single parameter investigations. In this regard, measurements of the wetting angle and area were conducted at solidified AgCuTi and CuSnTi alloys on SiC substrates. Based on these measurements, a regression model was generated, illustrating the influence of the brazing temperature, the roughness of the faying surfaces, the furnace atmosphere, and their interdependencies on the wetting and spreading behavior of the filler alloys. It was revealed that the behavior of the melts was significantly influenced by the varied brazing parameters, as well as by their interdependencies. This result was also predicted by the developed model and showed a high accuracy.

Self assembled molecular monolayers on high surface area materials as molecular getters

DOEpatents

King, David E.; Herdt, Gregory C.; Czanderna, Alvin W.

1997-01-01

The present invention relates to a gettering material that may be used as a filtration medium to remove pollutants from the environment. The gettering material comprises a high surface area material having a metal surface that chemically bonds n-alkanethiols in an organized manner thereby forming a molecular monolayer over the metal surface. The n-alkanethiols have a free functional group that interacts with the environment thereby binding specific pollutants that may be present. The gettering material may be exposed to streams of air in heating, ventilation, and air conditioning systems or streams of water to remove specific pollutants from either medium.

Mineral paragenesis on Mars: The roles of reactive surface area and diffusion

PubMed Central

Gil‐Lozano, Carolina; Uceda, Esther R.; Losa‐Adams, Elisabeth; Davila, Alfonso F.; Gago‐Duport, Luis

2017-01-01

Abstract Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water‐sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the transport of dissolved species may occur through the atmosphere‐water and water‐sediment interfaces. Here we present a suite of geochemical models designed to analyze the formation of secondary minerals in basaltic sediments on Mars, evaluating the role of (i) reactive surface areas and (ii) the transport of ions through a basalt sediment column. We consider fully open conditions, both to the atmosphere and to the sediment, and a kinetic approach for mineral dissolution and precipitation. Our models consider a geochemical scenario constituted by a basin (i.e., a shallow lake) where supersaturation is generated by evaporation/cooling and the starting point is a solution in equilibrium with basaltic sediments. Our results show that cation removal by diffusion, along with the input of atmospheric volatiles and the influence of the reactive surface area of primary minerals, plays a central role in the evolution of the secondary mineral sequences formed. We conclude that precipitation of evaporites finds more restrictions in basaltic sediments of small grain size than in basaltic sediments of greater grain size. PMID:29104844

Mineral paragenesis on Mars: The roles of reactive surface area and diffusion.

PubMed

Fairén, Alberto G; Gil-Lozano, Carolina; Uceda, Esther R; Losa-Adams, Elisabeth; Davila, Alfonso F; Gago-Duport, Luis

2017-09-01

Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water-sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the transport of dissolved species may occur through the atmosphere-water and water-sediment interfaces. Here we present a suite of geochemical models designed to analyze the formation of secondary minerals in basaltic sediments on Mars, evaluating the role of (i) reactive surface areas and (ii) the transport of ions through a basalt sediment column. We consider fully open conditions, both to the atmosphere and to the sediment, and a kinetic approach for mineral dissolution and precipitation. Our models consider a geochemical scenario constituted by a basin (i.e., a shallow lake) where supersaturation is generated by evaporation/cooling and the starting point is a solution in equilibrium with basaltic sediments. Our results show that cation removal by diffusion, along with the input of atmospheric volatiles and the influence of the reactive surface area of primary minerals, plays a central role in the evolution of the secondary mineral sequences formed. We conclude that precipitation of evaporites finds more restrictions in basaltic sediments of small grain size than in basaltic sediments of greater grain size.

Relationship between surface area for adhesion and tensile bond strength--evaluation of a micro-tensile bond test.

PubMed

Sano, H; Shono, T; Sonoda, H; Takatsu, T; Ciucchi, B; Carvalho, R; Pashley, D H

1994-07-01

The purpose of this study was to test the null hypothesis that there is no relationship between the bonded surface area of dentin and the tensile strength of adhesive materials. The enamel was removed from the occlusal surface of extracted human third molars, and the entire flat surface was covered with resin composite bonded to the dentin to form a flat resin composite crown. Twenty-four hours later, the bonded specimens were sectioned parallel to the long axis of the tooth into 10-20 thin sections whose upper part was composed of resin composite with the lower half being dentin. These small sections were trimmed using a high speed diamond bur into an hourglass shape with the narrowest portion at the bonded interface. Surface area was varied by altering the specimen thickness and width. Tensile bond strength was measured using custom-made grips in a universal testing machine. Tensile bond strength was inversely related to bonded surface area. At surface areas below 0.4 mm2, the tensile bond strengths were about 55 MPa for Clearfil Liner Bond 2 (Kuraray Co., Ltd.), 38 MPa for Scotchbond MP (3M Dental Products), and 20 MPa for Vitremer (3M Dental Products). At these small surface areas all of the bond failures were adhesive in nature. This new method permits measurement of high bond strengths without cohesive failure of dentin. It also permits multiple measurements to be made within a single tooth.

Enhanced specific surface area by hierarchical porous graphene aerogel/carbon foam for supercapacitor

NASA Astrophysics Data System (ADS)

Xin, Zhaopeng; Li, Weixin; Fang, Wei; He, Xuan; Zhao, Lei; Chen, Hui; Zhang, Wanqiu; Sun, Zhimin

2017-12-01

In this work, graphene aerogel/carbon foam is prepared by in situ inducing graphene aerogels in the pores of carbon foam. This novel hierarchical porous structure possesses a higher specific surface area as the introduction of graphene aerogels in carbon foam increases the proportion of micropores thus making it a superior candidate as electrodes for supercapacitors. The characterization and comparison of various properties of carbon foam and graphene aerogels/carbon foam have been investigated systematically. The result shows that specific surface area is up to 682.8 m2/g compared with initial carbon foam which increased about 55%, and the pore distribution curve shows more pore volume at 0.3 nm for F-CF/GA. It is demonstrated that the introduction of graphene aerogels not only increases the specific surface area, but also improves the conductivity, thus resulting in the reduction of the internal resistance and the improvement of the electrochemical performance. Consequently, graphene aerogel/carbon foam shows an excellent specific capacitance of 193.1 F/g at 1 A/g which is 72% higher than that of carbon foam acted as electrodes for supercapacitors.

30 CFR 933.761 - Areas designated unsuitable for surface coal mining by Act of Congress.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., forest, recreation area, or places; (f)(1) Where the proposed surface coal mining operation may adversely... mining by Act of Congress. 933.761 Section 933.761 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS...