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Determination of the effective permittivity of dielectric mixtures with the transmission line matrix methodDetermination of the effective permittivit…
2007
In this article, the effective permittivity of two-phase dielectric mixtures is calculated by applying the transmission line matrix (TLM) method. Two slightly different TLM algorithms are considered: a hybrid approach, which combines the TLM method with a subgriding technique based on dual capacitor circuits, to allow a refined description of the material, and a standard or pure TLM approach, which uses a mesh size smaller than the typical dimension of insertions in order to appropriately describe details of the geometry. A study of the statistical distribution of permittivity for insertions in random positions is also presented, showing that the effective permittivity of the mixture tends …
The necessary skills in higher education: Validation of competences
2012
This paper tries to show which competences have an impact on the success of students in higher education and especially in the first academic year. This situation also requires finding a way to acquire the competences which are necessary in this new experience that is the first year. A student is considered to be a person who has the basic competences required. Our role is to show how this person in higher education can acquire the other new competences that help him/her attain the positive results that we name ''success''. Normally, the higher education is a new experience because he/she has never been in these situations before. To reach this goal we will first demonstrate a method to con…
Initial strain effects in multilayer composite laminates
2001
A boundary integral formulation for the analysis of stress fields induced in composite laminates by initial strains, such as may be due to temperature changes and moisture absorption is presented. The study is formulated on the basis of the theory of generalized orthotropic thermo-elasticity and the governing integral equations are directly deduced through the generalized reciprocity theorem. A suitable expression of the problem fundamental solutions is given for use in computations. The resulting linear system of algebraic equations is obtained by the boundary element method and stress interlaminar distributions in the boundary-layer are calculated by using a boundary only discretization. …
Physical Cross Links in Amorphous PET, Influence of Cooling Rate and Ageing
2003
A Continuous Cooling Transformation (CCT) procedure can be used to distinguish the initial “state” of the amorphous PET samples produced upon solidification from the melt at different cooling rates. The material frozen at this stage behaves as a rubber when brought above the Tg due to the onset of physical cross links. The rubber is not a stable network, however, since physical cross links may eventually dissolve. Their size distribution, and possibly their number, depend on cooling rate and ageing. Some may be even stable above the glass transition and act as nuclei for further crystallization from the glass. Upon increasing cooling rate, size distribution becomes smaller and stability of …
Crystal structures, infrared-spectra, and thermal behavior of calcium hydrogenselenite monohydrate, Ca(HSeO3)2 · H2O, and dicalcium diselenite bis(hy…
1986
Abstract Calcium hydrogenselenite monohydrate and dicalcium diselenite bis(hydrogenselenite) were synthesized and their crystal structures determined. Crystal data for Ca(HSeO3)2 · H2O: a = 6.911(2), b = 7.369(2), c = 6.739(2) A, α = 90.51(3)°, β = 90.93(3)°, γ = 107.46(2)°, V = 327.3(2) A3, space group P 1 (No. 2), dcalcd = 3.19 M gm−3, Z = 2, and R = 0.036 for 1503 reflections. Data for Ca2(HSeO3)2(Se2O5): a = 14.719(4), b = 7.059(2), c = 11.793(2) A, β = 117.96(2)°, V = 1082.3(4) A3, space group C2 c (No. 15), dcalcd = 3.52 Mg m−3, Z = 4, and R = 0.047 for 1251 reflections. Both structures form a three-dimensional network. The coordination polyhedron around calcium is a monocapped trigon…
Designing Medical Devices Based on Silicon Polymeric Material with Controlled Release of Local Anesthetics
2012
The drug delivery systems that are the object of this article take the form of a polymer matrix made of silicone containing a drug. These devices can be used as patches for local dermal applications releasing the drug in a controlled manner. The model active agent, lidocaine hydrochloride was chosen from the range of local anesthetics. When the drug is restricted to the surface, it is released more rapidly than when it is allowed to spread evenly throughout the silicon structure. When hydrophilic polymers such as PVA and HEC are mixed in with the lidocaine hydrochloride and deposited on the surface of the polymer matrix, we observed that the burst effect was eliminated without modifying the…
EFFECT OF SHAPE ON POTATO AND CAULIFLOWER SHRINKAGE DURING DRYING
2000
ABSTRACT Shrinkage of potato cubes, parallelepipeds and cylinders was addressed during drying. A basic methodology by using image analysis was set-up in order to measure and monitor geometrical changes along the drying process. Both measurements by image analysis and directly with a calliper were carried out. Results from both methods showed a good agreement with no bias. Particle shape was found to influence shrinkage in a different way according to the axis. In fact the larger dimension shrinks less than the shorter one. This could be linked to the influence of the core drying in shrinkage. Experiments were also carried out for cauliflower stems. The difference in shrinkage between direct…
Bioactivation of the Fungal Phytotoxin 2,5-Anhydro-D-glucitol by Glycolytic Enzymesisan Essential Component of itsMechanism of Action
2002
An isolate of Fusarium solani, NRRL 18883, produces the natural phytotoxin 2,5-anhydro-ᴅ-glucitol (AhG). This fungal metabolite inhibited the growth of roots (I50 of 1.6 mᴍ), butit did nothave any in vitro inhibitory activity. The mechanism of action of AhG requires enzymatic phosphorylation by plant glycolytic kinases to yield AhG-1,6-bisphosphate (AhG-1,6- bisP), an inhibitor of Fru-1,6-bisP aldolase. AhG-1,6-bisP had an I50 value of 570 μᴍ on aldolase activity, and it competed with Fru-1,6-bisP for the catalytic site on the enzyme, with a Ki value of 103 μᴍ. The hydroxyl group on the anomeric carbon of Fru-1,6-bisP is required for the formation of an essential covalent bond to ζ amino fu…
WWOX, a Chromosomal Fragile Site Gene and its Role in Cancer
2006
Allelic imbalances affecting the long arm of chromosome 16 have been extensively reported in the literature as common abnormalities observed in various carcinoma types, As a result of loss of heterozygosity (LOH) studies in breast cancer, we delimited a genomic area within chromosome 16 that demonstrated the highest frequency of abnormalities. This led us to the identification and cloning of WWOX, a candidate tumor suppressor gene (TSG) that spans a fragile region of DNA located at 16q23.3-24.1 (FRA16D: the second most active common chromosomal fragile site in the human genome). This gene encodes a protein that contains two WW domains responsible of protein-protein interactions and a short-…
Experimental Method for Determining Forces at Bending of Perforated Plates
2017
Abstract This paper describes the method of calculating the forces which appear at the bending of perforated plates with holes of different shapes and placed in different patterns, by means of a dynamometric table which uses resistive tensometric transducers (strain gauges). It also describes an instrument for the recording of data from the dynamometric table, a tool created with the aid of the “TestPoint” software which, beneath the data recording, ensures the filtering and statistic processing of data. The obtained results are displayed in comparative graphs for six types of perforated plates, as well as for an unperforated plate.