On the relationship between induced polarization and surface area in metal-sand and clay-sand mixtures

Geophysics ◽  
2006 ◽  
Vol 71 (2) ◽  
pp. A1-A5 ◽  
Author(s):  
Lee Slater ◽  
Dimitrios Ntarlagiannis ◽  
DeBonne Wishart
Keyword(s):  
Surface Area ◽  
Gas Adsorption ◽  
Induced Polarization ◽  
Nitrogen Gas ◽  
Volume Formula ◽  
Percentage Weight ◽  
Mineral Constituent ◽  
Cole Model ◽  
The Relationship ◽  
Electrical Data

Induced polarization (IP) measurements were conducted on saturated kaolinite-, iron-, and magnetite-sand mixtures as a function of varying percentage weight of a mineral constituent: 0%–100% for iron and magnetite and 0%–32% for kaolinite. We determined the specific surface area for each mineral using nitrogen gas adsorption, where the porosity of each mixture was calculated from weight loss after drying. We fit a Cole-Cole model (Cole and Cole, 1941) to the electrical data obtained for the magnetite and iron mixtures. In contrast, the kaolinite mixtures showed a power-law dependence of phase-on frequency. The global polarization magnitude we obtained from the Cole-Cole modeling of the iron and magnetite mixtures displays a single, near-linear dependence on the ratio of surface area to pore volume ([Formula: see text]) calculated for the mixtures. A similar relationship is found using a local measure of polarization (imaginary conductivity at 1 Hz) for the clay-sand mixtures. The [Formula: see text] appears to be a critical parameter for determining IP in both metallic- and clay-containing soils. This result is not easily reconciled with traditional models of induced polarization.

On the relationship between iron concentration and induced polarization in marsh soils

Geophysics ◽  
2007 ◽  
Vol 72 (1) ◽  
pp. A1-A5 ◽  
Author(s):  
Nasser Mansoor ◽  
Lee Slater
Keyword(s):  
Surface Area ◽  
Iron Concentration ◽  
Induced Polarization ◽  
Model Parameters ◽  
Soil Geochemistry ◽  
Iron Cycling ◽  
Volume Formula ◽  
Cole Model ◽  
The Relationship ◽  
Fluid Conductivity

Induced polarization (IP) measurements [Formula: see text] were conducted on seventeen clay and peat marsh soils that were subsequently analyzed for heavy metal concentrations, moisture content, organic matter, porosity, specific surface area, and pore fluid conductivity. A Cole-Cole model was fit to each sample and model parameters analyzed in terms of physicochemical properties. We found a linear relation between the normalized chargeability [Formula: see text] and estimated surface area to pore volume [Formula: see text] when iron content (ranging from 0.25% to 1.63% by volume) is accounted for as a polarizable element of the soil. In fact, the dependence of [Formula: see text] on volumetric Fe concentration per unit volume of the bulk soil is described by a linear relationship with a correlation coefficient [Formula: see text] of 0.94. As Fe concentration is a critical biogeochemical parameter, our findings suggest that IP measurements may provide a hitherto unrecognized approach to probing soil geochemistry, iron cycling and anaerobic microbial activity. Furthermore, our results yield insights into physicochemical controls on IP in natural soils.

Electrical properties of iron-sand columns: Implications for induced polarization investigation and performance monitoring of iron-wall barriers

Geophysics ◽  
2005 ◽  
Vol 70 (4) ◽  
pp. G87-G94 ◽  
Author(s):  
Lee D. Slater ◽  
Jaeyoung Choi ◽  
Yuxin Wu
Keyword(s):  
Relaxation Time ◽  
Surface Area ◽  
Performance Monitoring ◽  
Electrical Response ◽  
Induced Polarization ◽  
Iron Hydroxides ◽  
Interfacial Chemistry ◽  
Reactive Iron ◽  
Volume Formula ◽  
And Performance

We investigate the electrical response (0.1–1000 Hz) of reactive iron barriers by making measurements on zero valent iron ([Formula: see text])-sand columns under the following conditions: (1) variable [Formula: see text] surface area (0.1–100% by volume [Formula: see text] under constant electrolyte chemistry; (2) variable electrolyte activity (0.01–1 mol/liter), valence (mono trivalent), and pH under constant [Formula: see text]-sand composition; and (3) forced precipitation of iron hydroxides and iron carbonates on the [Formula: see text] surface. We model the measurements in terms of conduction magnitude, polarization magnitude, and polarization relaxation time. Our key findings are: (a) Polarization magnitude exhibits a linear relation to the surface area of [Formula: see text], whereas conduction magnitude is only weakly dependent on the [Formula: see text] concentration below 30% by volume [Formula: see text]. (b) Polarization magnitude shows a power law relation to electrolyte activity, with exponents decreasing from 0.9 for monovalent solutions to 0.7 for trivalent solutions. (c) The relaxation time parameter depends on activity and valence in a manner that is partly consistent with the variation in double layer thickness predicted from theory. (d) pH exerts minor control on the electrical parameters. (e) Polarization magnitude and relaxation time both increase as a result of precipitation induced on the surface of [Formula: see text]. Our results show that induced polarization parameters systematically change in response to changes in the [Formula: see text]-electrolyte interfacial chemistry.

Nano-Porous Silica (SiO2) and Iron-Silica (Fe2O3-SiO2 ) Composite Synthesis via Reverse Microemulsion for Catalytic Applications

2006 ◽  
Vol 306-308 ◽  
pp. 1127-1132 ◽  
Author(s):  
Lal Said Jan ◽  
Radiman Shahidan ◽  
Iskandar Idris Yaacob
Keyword(s):  
Surface Area ◽  
Gas Adsorption ◽  
Porous Silica ◽  
Mesoporous Structure ◽  
Reverse Microemulsion ◽  
Scanning Calorimetry ◽  
Nitrogen Gas ◽  
Nanostructured Particles ◽  
Nanostructured Silica ◽  
Adsorption Desorption

Nanostructured silica and silica-iron composite particles were prepared using water-in-oil (w/o) reverse microemulsion. Double microemulsion technique is used for the synthesis of both types of nanostructured particles. X-ray Diffractometry (XRD), scanning electron microscopy (SEM), nitrogen gas adsorption-desorption isotherm technique, and differential scanning calorimetry (DSC) were used to characterize the synthesized particles. The gas adsorptiondesorption measurements revealed a mesoporous structure for the silica (SiO2) particles with a surface area of 300.49 m2/g. Upon the addition of an iron microemulsion to the silica microemulsion, silica-iron nanocomposite (Fe2O3-SiO2) was achieved which gave a surface area of 69.87 m2/g. This indicated a positive impregnation of the silica mesopores that was further confirmed by energy dispersive spectrometry (EDS). The XRD of bare SiO2 gave a single broad peak whereas SiO2-Fe2O3 demonstrated additional peaks confirming α-iron insertion in mesoporous silica. DSC curve with its characteristic peaks also indicated the presence of iron nanoparticles within silica. The product silica-iron nanocomposite has potential catalytic and semiconducting applications.

Surface Fractal Dimensionality and Hygroscopicity for Heated Wood

Holzforschung ◽  
2003 ◽  
Vol 57 (3) ◽  
pp. 289-294 ◽  
Author(s):  
T. Nakano ◽  
J. Miyazaki
Keyword(s):  
Temperature Dependence ◽  
Gas Adsorption ◽  
Heating Temperature ◽  
Chemical Properties ◽  
Fractal Dimensionality ◽  
Hydroxyl Groups ◽  
Fractal Surface ◽  
Nitrogen Gas ◽  
Chemical Changes ◽  
The Relationship

Summary The relationship between hygroscopicity and the microsurface of heated wood was examined using the fractal surface dimensionality. The hygroscopicity of heated wood decreased with the increase in heating temperature to 250°C, and then decreased again above 350°C after increasing up to 350°C. This change corresponded to chemical changes in the wood, especially a reduction in hydroxyl groups, up to 250°C, and to the temperature dependence of the fractal dimensionality calculated from nitrogen gas adsorption above 250°C. The fractal dimensionality increased gradually from 100 to 250°C, followed by a rapid increase above 250°C with a peak at 350°C, and leveled off above 400°C. From the results, it is concluded that hygroscopicity of heated wood changes at 250°C and that it is dependent upon the chemical properties of wood below 250°C and upon the surface complexity above 250°C.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

The use of Body Surface Index as a Better Clinical Health indicators Compare to Body Mass Index and Body Surface Area for Clinical Application

2018 ◽  
pp. 131-136
Author(s):  
Shirazu I. ◽  
Theophilus. A. Sackey ◽  
Elvis K. Tiburu ◽  
Mensah Y. B. ◽  
Forson A.
Keyword(s):  
Surface Area ◽  
Body Surface Area ◽  
Clinical Application ◽  
Body Surface ◽  
Body Height ◽  
Health Indicators ◽  
The Body ◽  
Body Parameters ◽  
The Relationship ◽  
Individual Body

The relationship between body height and body weight has been described by using various terms. Notable among them is the body mass index, body surface area, body shape index and body surface index. In clinical setting the first descriptive parameter is the BMI scale, which provides information about whether an individual body weight is proportionate to the body height. Since the development of BMI, two other body parameters have been developed in an attempt to determine the relationship between body height and weight. These are the body surface area (BSA) and body surface index (BSI). Generally, these body parameters are described as clinical health indicators that described how healthy an individual body response to the other internal organs. The aim of the study is to discuss the use of BSI as a better clinical health indicator for preclinical assessment of body-organ/tissue relationship. Hence organ health condition as against other body composition. In addition the study is `also to determine the best body parameter the best predict other parameters for clinical application. The model parameters are presented as; modeled height and weight; modelled BSI and BSA, BSI and BMI and modeled BSA and BMI. The models are presented as clinical application software for comfortable working process and designed as GUI and CAD for use in clinical application.

Influence of intramolecular interactions on carbon dioxide gas adsorption capacity in Mesoporous Imine polymers

2018 ◽  
Author(s):  
Jaya Prakash Madda ◽  
Pilli Govindaiah ◽  
Sushant Kumar Jena ◽  
Sabbhavat Krishna ◽  
Rupak Kishor
Keyword(s):  
Carbon Dioxide ◽  
Adsorption Capacity ◽  
Density Functional ◽  
Gas Adsorption ◽  
Ambient Pressure ◽  
Condensation Reaction ◽  
Intramolecular Interactions ◽  
Carbon Dioxide Adsorption ◽  
Nitrogen Gas ◽  
Adsorption Characteristic

<p>Covalent organic Imine polymers with intrinsic meso-porosity were synthesized by condensation reaction between 4,4-diamino diphenyl methane and (para/meta/ortho)-phthaladehyde. Even though these polymers were synthesized from precursors of bis-bis covalent link mode, the bulk materials were micrometer size particles with intrinsic mesoporous enables nitrogen as well as carbon dioxide adsorption in the void spaces. These polymers were showed stability up to 260<sup>o</sup> centigrade. Nitrogen gas adsorption capacity up to 250 cc/g in the ambient pressure was observed with type III adsorption characteristic nature. Carbon dioxide adsorption experiments reveal the possible terminal amine functional group to carbamate with CO<sub>2</sub> gas molecule to the polymers. One of the imine polymers, COP-3 showed more carbon dioxide sorption capacity and isosteric heat of adsorption (Q<sub>st</sub>) than COP-1 and COP-2 at 273 K even though COP-3 had lower porosity for nitrogen gas than COP-1 and COP-2. We explained the trends in gas adsorption capacities and Qst values as a consequence of the intra molecular interactions confirmed by Density Functional Theory computational experiments on small molecular fragments.</p>

The relationship between brain structure and general psychopathology in preadolescents

2020 ◽  
Author(s):  
Louise Mewton ◽  
Briana Lees ◽  
Lindsay Squeglia ◽  
Miriam K. Forbes ◽  
Matthew Sunderland ◽  
...  
Keyword(s):  
Mental Disorders ◽  
Surface Area ◽  
Brain Structure ◽  
Parental Education ◽  
Mental Illnesses ◽  
General Psychopathology ◽  
Control Approach ◽  
Cortical Volume ◽  
Subcortical Regions ◽  
The Relationship

Categorical mental disorders are being recognized as suboptimal targets in clinical neuroscience due to poor reliability as well as high rates of heterogeneity within, and comorbidity between, mental disorders. As an alternative to the case-control approach, recent studies have focused on the relationship between neurobiology and latent dimensions of psychopathology. The current study aimed to investigate the relationship between brain structure and psychopathology in the critical preadolescent period when psychopathology is emerging. This study included baseline data from the Adolescent Brain and Cognitive Development (ABCD) Study® (n = 11,721; age range = 9-10 years; male = 52.2%). General psychopathology, externalizing, internalizing, and thought disorder dimensions were based on a higher-order model of psychopathology and estimated using Bayesian plausible values. Outcome variables included global and regional cortical volume, thickness, and surface area. Higher levels of psychopathology across all dimensions were associated with lower volume and surface area globally, as well as widespread and pervasive alterations across the majority of cortical and subcortical regions studied, after adjusting for sex, race/ethnicity, and parental education. The relationships between general psychopathology and brain structure were attenuated when adjusting for cognitive functioning. There was evidence of a relationship between externalizing psychopathology and frontal regions of the cortex that was independent of general psychopathology. The current study identified lower cortical volume and surface area as transdiagnostic biomarkers for general psychopathology in preadolescence. The widespread and pervasive relationships between general psychopathology and brain structure may reflect cognitive dysfunction that is a feature across a range of mental illnesses.

Probing the performance of imide linked micro-porous polymers for enhanced CO2 gas adsorption applications

2021 ◽  
Author(s):  
Narendran Rajendran ◽  
Ali A. Husain ◽  
Saad Makhseed
Keyword(s):  
Surface Area ◽  
Gas Adsorption ◽  
Oxidative Polymerization ◽  
Porous Polymers ◽  
Bet Surface Area ◽  
Co2 Gas

Three new carbazole containing cross-linked polymers namely AH-Poly, TM-PDA-Poly and TMB-PDA-Poly were designed and successfully synthesized by an oxidative polymerization protocol. The prepared AH-Poly showed a specific BET surface area...

Sign in / Sign up

Export Citation Format

Share Document