Search results for "conductivity"

Thermoplastic Properties of Endodontic Gutta-percha: A Thermographic In Vitro Study

2014

Abstract Introduction Endodontic gutta-percha undergoes deformation at temperatures above 65°C. The temperature influence of heat carriers on gutta-percha cones was investigated in vitro. Methods Six single-rooted extracted teeth were embedded in resin and fixed. The root canals were prepared (ProFile; Dentsply Maillefer, Ballaiques, Switzerland) to different tapers and bisected. Thermographic images when heating the gutta-percha cones (Roeko, Langenau, Germany) with a heat carrier (ML .12; SybronEndo, Orange, CA) at 1 and 5 mm from the working length were made with an infrared thermal imaging camera (ThermaCam P640; Flir Systems, Taby, Sweden). The device temperature was preset at 200°C. T…

Reentrant Fulde-Ferrell-Larkin-Ovchinnikov superfluidity in the honeycomb lattice

2017

We study superconducting properties of population-imbalanced ultracold Fermi mixtures in the honeycomb lattice that can be effectively described by the spin-imbalanced attractive Hubbard model in the presence of a Zeeman magnetic field. We use the mean-field theory approach to obtain ground state phase diagrams including some unconventional superconducting phases such as the Fulde--Ferrell--Larkin--Ovchinnikov (FFLO) phase. We show that this phase is characterized by atypical behaviour of the Cooper pairs total momentum in the external magnetic field. We show that the momentum changes its value as well as direction with change of the system parameters. We discuss the influence of van Hove s…

Single-particle properties of the Hubbard model in a novel three-pole approximation

2017

We study the 2D Hubbard model using the Composite Operator Method within a novel three-pole approximation. Motivated by the long-standing experimental puzzle of the single-particle properties of the underdoped cuprates, we include in the operatorial basis, together with the usual Hubbard operators, a field describing the electronic transitions dressed by the nearest-neighbor spin fluctuations, which play a crucial role in the unconventional behavior of the Fermi surface and of the electronic dispersion. Then, we adopt this approximation to study the single-particle properties in the strong coupling regime and find an unexpected behavior of the van Hove singularity that can be seen as a prec…

Comments on “Predicting the Effect of Rock Fragments on Saturated Soil Hydraulic Conductivity”

2007

A simplified falling-head tecnique for rapid determination of field-saturated hydraulic conductivity

2004

Simplified measurements of the field-saturated hydraulic conductivity, K fs , require short duration experiments, small water volumes, and easily transportable equipment. A simplified falling-head (SFH) technique for the rapid determination of K fs has been developed and tested. The technique consists in applying a small volume of water on a soil surface, confined by a ring inserted a short distance into the soil, and then measuring the time from the application of water to the instant at which the surface area is no longer covered by water. A measurement of the initial and field-saturated soil water contents, and an estimate of the α* parameter of the Gardner's exponential model are then u…

TTF charge transfer salts containing cyanometallate anions [M(phen)(CN)4]− (M=Cr or Fe; phen=1,10-phenanthroline)

2006

Abstract Two new charge transfer salts of TTF with the counter anions [M(phen)(CN) 4 ] − (phen = 1,10-phenanthroline, M = Cr ( I ) and Fe ( II )) are described. The structures consist of alternating stacks of dimerised TTF + cations and [M(phen)(CN) 4 ] − anions and they are linked together by many short S⋯S contacts and hydrogen bonds. Within the organic stack, two dimerised TTF + cations are arranged in a slipped face-to-face mode with short intra-dimer and long inter-dimer S⋯S distances. Strong antiferromagnetic exchange was found in the TTF + dimers. Conductivity measurements show that compound I is a semiconductor.

The influence of external uniaxial stretching on the electromigration and diffusion of hydrogen in iron

2009

Electromigration and diffusion of hydrogen in iron, depending on unit elongation, were investigated. The resistivity method was applied in the investigations. It was found that the obtained experimental results cannot be described by means of a single flux of hydrogen, which diffuses in the electric field. In order to explain the obtained results, we assumed the existence of the following two fluxes of hydrogen in the stretched metal: migration, according to the interstitial mechanism, and migration according to the interstitial-defective mechanism. The dependence of effective valences and diffusion coefficients for both mechanisms were determined.

Physical and hydraulic characterization of a clay soil at the plot scale

2010

Summary The soil physical and hydraulic properties have to be determined for interpreting and simulating many hydrological processes. An investigation was carried out to determine the physical and hydraulic characteristics of a clay soil at the plot scale. An intensive sampling of the surface soil layer of two plots of 4 × 11 m2 was carried out by measuring, for each plot, dry soil bulk density, ρb, and antecedent soil water content, θi, at 88 sampling points and field-saturated soil hydraulic conductivity, Kfs, at 176 sampling points. A wide range of Kfs values (0.7–5107 mm h−1) were measured by the Simplified Falling Head (SFH) technique. For each variable, the two plots yielded very simi…

High resolution remote estimation of soil surface water content by a thermal inertia approach

2009

Summary The spatial distribution of soil surface water content in a bare soil was evaluated by a thermal inertia approach from high resolution visible/near infrared (VIS/NIR) and thermal infrared (TIR) airborne data. Given that the relationship between the thermal inertia and the soil water content strongly depends on the accurate estimation of the soil thermal conductivity, two different empirical models were applied to estimate it. Remotely estimated water contents were tested with time domain reflectometry (TDR) measurements collected on a 110 × 90 m 2 bare field in coincidence with airborne over-flights. The thermal conductivity model by Johansen (1975) produced more accurate estimates …

Developing an erodibility triangle for soil textures in semi-arid regions, NW Iran

2016

Abstract There is a strong need to develop a simple method for rapid estimation of erodibility using readily available data. In this study, soil erodibility was measured using eleven soil textures at the plot scale (60 cm × 80 cm) on a slope of 9% in a semi-arid region. A total of 110 soil erosion experiments were conducted using ten simulated rainfalls (50 mm h− 1 for 30 min). A regression model was developed based on silt and clay content (R2 = 0.82, p