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Sample records for apparent molar volumes

  1. Osmotic coefficients and apparent molar volumes of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid in alcohols

    International Nuclear Information System (INIS)

    Highlights: • Physical and osmotic properties of [HMim][TfO] in alcohols are reported. • Apparent molar properties and osmotic coefficients were obtained. • Apparent molar volumes were fitted using a Redlich–Meyer type equation. • The osmotic coefficients were modeled with the Extended Pitzer and the MNRTL models. -- Abstract: In this work, density for the binary mixtures of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate in alcohols (1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol) was measured at T = 323.15 K and atmospheric pressure. From this property, the corresponding apparent molar volumes were calculated and fitted to a Redlich–Meyer type equation. For these mixtures, the osmotic and activity coefficients, and vapor pressures of these binary systems were also determined at the same temperature using the vapor pressure osmometry technique. The experimental osmotic coefficients were modeled by the Extended Pitzer model of Archer. The parameters obtained in this correlation were used to calculate the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures

  2. Apparent and partial molar volumes of long-chain alkyldimethylbenzylammonium chlorides and bromides in aqueous solutions at T=15 deg. C and T=25 deg. C[Alkyldimethylbenzylammonium chlorides; Alkyldimethylbenzylammonium bromides; Micellization; Density; Apparent molar volumes

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Perez, A.; Ruso, J.M.; Nimo, J.; Rodriguez, J.R. E-mail: fmjulio@usc.es

    2003-12-01

    Density measurements of dodecyl- (C{sub 12}DBACl), tetradecyl- (C{sub 14}DBACl), hexadecyldimethylbenzylammonium chloride (C{sub 16}DBACl) and of decyl- (C{sub 10}DBABr) and dodecyldimethylbenzylammonium bromide (C{sub 12}DBABr) in aqueous solutions at T=15 deg. C and T=25 deg. C have been carried out. From these results, apparent and partial molar volumes were calculated. Positive deviations from the Debye-Hueckel limiting law provide evidence for limited association at concentrations below the critical micelle concentration. The change of the apparent molar volume upon micellization was calculated. The relevant parameters have been presented in function of the alkyl chain length. Apparent molar volumes of the present compounds in the micellar phase, V{sub phi}{sup m}, and the change upon micellization, {delta}V{sub phi}{sup m}, have been discussed in terms of temperature and type of counterion.

  3. The (p, ρ, T) properties and apparent molar volumes Vφ of (ZnBr2 + C2H5OH)

    International Nuclear Information System (INIS)

    The (p, ρ, T) properties and apparent molar volumes Vφ of ZnBr2 in ethanol at temperatures (293.15 to 393.15) K and pressures up to p = 40 MPa are reported. The measurements were made with a recently developed vibration-tube densimeter. The system was calibrated using double-distilled water, methanol, ethanol, and aqueous NaCl solutions. The experiments were carried out at molalities of m = (0.05681, 0.16958, 0.30426, 0.43835, 0.93055, 1.49016, and 1.88723) mol . kg-1 using zinc bromide. An empirical correlation for the density of (ZnBr2 + C2H5OH) with pressure, temperature, and molality has been derived. This equation of state was used to calculate other volumetric properties such as isothermal compressibility, isobaric thermal expansibility, the differences in specific heat capacities at constant pressures and volumes, apparent molar volumes of ZnBr2 in ethanol, and partial molar volumes of both components.

  4. DENSITY, REFRACTIVE INDEX, APPARENT VOLUMES AND EXCESS MOLAR VOLUMES OF FOUR PROTIC IONIC LIQUIDS + WATER AT T=298.15 AND 323.15 K

    Directory of Open Access Journals (Sweden)

    R. Rocha Pinto

    2015-09-01

    Full Text Available AbstractDensities and refractive index of binay mixtures of water with four protic ionic liquids, based on ammonium and fatty acids, were measured at 298.15 and 323.15 K, under atmospheric pressure. Apparent and excess molar volumes were obtained by experiments and fitting data to the Redlich-Meyer (RM, Redlich-Kister (RK and Prigogine-Flory-Patterson (PFP equations. The molar volume values were high, suggesting strong ion-solvent interaction. The same interaction also became stronger as the temperature increased. Excess volume values were negative, indicating that packing efficiency ability or attractive interactions occurred in mixtures of ionic liquid + water. The errors (AARD for the properties in excess were in the range of 1.8% to 7.2%. The PFP error for the apparent volume was in the range of 0.34% to 0.06%, lower than the RM error for the same property, which was in the range of 0.70 to 1.55%. The Gladstone-Dale model was applied to correlate the refractive index of the binary mixture with the density from the values of both pure components.

  5. Excess Molar Volume and Apparent Molar Volume of Binary Mixtures of 2—Methyl—3—buten—2—ol with 1—Alcohol at 298.15K

    Institute of Scientific and Technical Information of China (English)

    LIUDixia; LIHaoran; 等

    2002-01-01

    Excess molar volumes (VmE) of binary mixtures of 2-methyl-3-buten-2-ol[CH3C(OH)(CH3)CHCH2] with four 1-alcohols:methanol,ethanol,1-propanol and 1-butanol at 298.15K and atmospheric pressure are derived from density measurements with a vibrating-tube densimeter.All the excess volumes are negative in the systems over the entire composition range. The results are correlated with the Redlich-Kister equation.The effects of chain length of 1-alcohols on VmE are discussed.The apparent molar volumes of 2-methyl-3-buten-2-ol and 1-alcohols are calculated respectively.

  6. Composition et volume molaire apparent des gels Ca_Si, une approche expérimentaleComposition and apparent molar volume of Ca_Si gels, an experimental approach

    Science.gov (United States)

    Perruchot, Alain; Massard, Pierre; Lombardi, Jérôme

    2003-11-01

    Synthetic CaSi gels of various compositions were prepared from sodium metasilicate and calcium chloride solutions. These synthetic CaSi gels are good analogues of fresh natural gels found within concrete affected by Alkalis-Silica Reaction (ASR). Results show that these synthetic gels in equilibrium with their formation solutions present an optimum of composition for a molar ratio CaO/SiO 2=(C/S) g≅0.48. Correspondingly, this characteristic value of (C/S) g denotes a rearrangement in the structure of gels accounted for the variation with (C/S) g of the apparent molar volume Vg. To cite this article: A. Perruchot et al., C. R. Geoscience 335 (2003).

  7. Apparent molar volumes and viscosity B-coefficients of caffeine in aqueous thorium nitrate solutions at T = (298.15, 308.15, and 318.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Biswajit, E-mail: biswachem@gmail.co [Department of Chemistry, University of North Bengal, Darjeeling 734013 (India); Roy, Pran Kumar; Sarkar, Bipul Kumar; Brahman, Dhiraj [Department of Chemistry, University of North Bengal, Darjeeling 734013 (India); Roy, Mahendra Nath, E-mail: mahendraroy2002@yahoo.co.i [Department of Chemistry, University of North Bengal, Darjeeling 734013 (India)

    2010-03-15

    Apparent molar volumes phi{sub V} and viscosity B-coefficients for caffeine in (0.00, 0.03, 0.05, and 0.07) mol . dm{sup -3} aqueous thorium nitrate, Th(NO{sub 3}){sub 4}, solutions were determined from solution density and viscosity measurements over the temperature range (298.15 to 318.15) K as function of concentration of caffeine and the relation: phi{sub V}{sup 0}=a{sub 0}+a{sub 1}T+a{sub 2}T{sup 2}, have been used to describe the temperature dependence of the standard partial molar volumes phi{sub V}{sup 0}. These results have been used to deduce the standard volumes of transfer DELTAphi{sub V}{sup 0} and viscosity B-coefficients of transfer DELTAB for caffeine from water to aqueous Th(NO{sub 3}){sub 4} solutions for rationalizing various interactions in the ternary solutions. The structure-making or breaking ability of caffeine has been discussed in terms of the sign of (delta{sup 2}phi{sub V}{sup 0}/deltaT{sup 2}){sub P}. The Friedman-Krishnan co-sphere model was used to explain the transfer volume of caffeine with increasing Th(NO{sub 3}){sub 4} molarity. The activation parameters of viscous flow for the ternary solutions were also discussed in terms of transition state theory.

  8. (p, ρ, T) properties and apparent molar volumes V φ of CaCl2 in methanol at T = (298.15 to 398.15) K and pressure up to 40 MPa

    International Nuclear Information System (INIS)

    The (p, ρ, T) properties and apparent molar volumes V φ of CaCl2 in methanol at T = (298.15 to 398.15) K, at pressures up to 40 MPa are reported, and apparent molar volumes have been evaluated. The experimental (p, ρ, T) values were described by an equation of state. The experiments were carried out at m = (0.10819, 0.28529, 0.65879 and 2.39344) mol . kg-1 of calcium chloride

  9. Apparent molar volumes of aqueous calcium chloride to 250{degrees}C, 400 bars, and from molalities of 0.242 to 6.150

    Energy Technology Data Exchange (ETDEWEB)

    Oakes, C.S.; Bodnar, R.J. [Virginia Polytechnic Inst. and Univ., Blacksburg, VA (United States); Simonson, J.M. [Univ. of California, Berkeley, CA (United States)

    1995-09-01

    Relative densities of CaCl{sub 2}(aq) with 0.242 {le} m/(mol-kg{sup {minus}1}) {le} 6.150 were measured with vibrating-tube densimeters between 25 and 250{degrees}C and near 70 and 400 bars. Apparent molar volumes V{sub {null}} calculated from the measured density differences were represented with the Pitzer ion-interaction treatment, with appropriate expressions chosen for the temperature and pressure dependence of the virial coefficients of the model. It was found that the partial molar volume at infinite dilution V{sub {null}}{sup o}, and the second and third virial coefficients B{sup v} and C{sup v}, were necessary to represent V{sub {null}} near the estimated experimental uncertainty. The ionic-strength dependent {Beta}{sup 1}{sup v} term in the B{sup v} coefficient was included in the fit. The representation for V{sub {null}} has been integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. The volumetric data indicate that the logarithm of the mean ionic activity coefficient, ln {gamma}{plus_minus}(CaCl{sub 2}), increases by a maximum of 0.3 at 400 bars, 250{degrees}C, and 6 mol-kg{sup {minus}1} as compared with its value at saturation pressure.

  10. Apparent molar volumes and apparent molar heat capacities of aqueous adonitol, dulcitol, glycerol, meso-erythritol, myo-inositol, D-sorbitol, and xylitol at temperatures from (278.15 to 368.15) K and at the pressure 0.35 MPa

    International Nuclear Information System (INIS)

    Apparent molar volumes V φ were determined for aqueous adonitol, dulcitol, glycerol, meso-erythritol, myo-inositol, D-sorbitol, and xylitol at temperatures from (278.15 to 368.15) K and at the pressure 0.35 MPa, and apparent molar heat capacities C p,φ of the same solutions were determined at temperatures from (278.15 to 363.15) K at the same pressure. Molalities m/(mol . kg-1) of the solutions were in the range (0.02 ≤ m ≤ 3.2) for adonitol, (0.02 ≤ m ≤ 0.15) for dulcitol, (0.02 ≤ m ≤ 5.0) for glycerol, (0.02 ≤ m ≤ 3.0) for meso-erythritol, (0.02 ≤ m ≤ 0.5) for myo-inositol, (0.02 ≤ m ≤ 2.0) for D-sorbitol, and (0.02 ≤ m ≤ 2.7) for xylitol. A vibrating tube densimeter was used to obtain solution densities and a fixed-cell temperature scanning calorimeter was used to obtain heat capacities. Values of V φ and C p,φ for these sugar alcohols are discussed relative to one another and compared to values from the literature, where available

  11. Apparent molar volumes and apparent molar heat capacities of aqueous adonitol, dulcitol, glycerol, meso-erythritol, myo-inositol, D-sorbitol, and xylitol at temperatures from (278.15 to 368.15) K and at the pressure 0.35 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Blodgett, M.B. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, 84602-5700 (United States); Ziemer, S.P. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, 84602-5700 (United States); Brown, B.R. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, 84602-5700 (United States); Niederhauser, T.L. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, 84602-5700 (United States); Woolley, E.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, 84602-5700 (United States)]. E-mail: earl_woolley@byu.edu

    2007-04-15

    Apparent molar volumes V {sub {phi}} were determined for aqueous adonitol, dulcitol, glycerol, meso-erythritol, myo-inositol, D-sorbitol, and xylitol at temperatures from (278.15 to 368.15) K and at the pressure 0.35 MPa, and apparent molar heat capacities C {sub p,{phi}} of the same solutions were determined at temperatures from (278.15 to 363.15) K at the same pressure. Molalities m/(mol . kg{sup -1}) of the solutions were in the range (0.02 {<=} m {<=} 3.2) for adonitol, (0.02 {<=} m {<=} 0.15) for dulcitol, (0.02 {<=} m {<=} 5.0) for glycerol, (0.02 {<=} m {<=} 3.0) for meso-erythritol, (0.02 {<=} m {<=} 0.5) for myo-inositol, (0.02 {<=} m {<=} 2.0) for D-sorbitol, and (0.02 {<=} m {<=} 2.7) for xylitol. A vibrating tube densimeter was used to obtain solution densities and a fixed-cell temperature scanning calorimeter was used to obtain heat capacities. Values of V {sub {phi}} and C {sub p,{phi}} for these sugar alcohols are discussed relative to one another and compared to values from the literature, where available.

  12. Measurement and COrrelation on Viscosity and Apparent Molar Volume of Ternary System for L—ascorbic Acid in Aqueous D—Glucose and Sucrose Solutions

    Institute of Scientific and Technical Information of China (English)

    赵长伟; 马沛生

    2003-01-01

    Visosities and densities at ,several temperatures from 293.15 K to 313.15K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations.The parameters of density,Viscosity coefficient B and partial molar volume are calculated by regression.The experimental results show that densities and viscositis decrease as temperature increases at the same solute and solvent (glucose and sucrose aueous solution)concentrations,and increase with concentration of glucose and sucrose at the same solute concentration and temperature,B increases with concentration of glucose and sucrose and temaperature,L-ascorbic acid is sturcture-breaker or structure-making for the glucose and sucrose aqueous solutions ,Furthermore,the solute-solvent interactions in ternary systems of water-glucose-electrolyte and water-sucrose-electrolyte are discussed.

  13. 2-甲基-3-丁烯-2-醇+直链一元醇二元体系的过量摩尔体积和表观摩尔体积298.15 K)%Excess Molar Volume and Apparent Molar Volume of Binary Mixtures of 2-Methyl-3-buten-2-ol with 1-Alcohol at 298.15 K

    Institute of Scientific and Technical Information of China (English)

    刘迪霞; 李浩然; 邓东顺; 韩世钧

    2002-01-01

    Excess molar volumes (VEm) of binary mixtures of 2-methyl-3-buten-2-ol [CH3C(OH)(CH3)CHCH2]with four 1-alcohols: methanol, ethanol, 1-propanol and 1-butanol at 298.15 K and atmospheric pressure are derived from density measurements with a vibrating-tube densimeter. All the excess volumes are negative in the systems over the entire composition range. The results are correlated with the Redlich-Kister equation. The effects of chain length of 1-alcohols on VmE are discussed. The apparent molar volumes of 2-methyl-3-buten-2-ol and 1-alcohols are calculated respectively.

  14. Osmotic and apparent molar properties of binary mixtures alcohol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid

    International Nuclear Information System (INIS)

    Highlights: ► Osmotic and physical properties of binary mixtures {alcohol + [BMim][TfO]} were measured. ► From experimental data, apparent molar properties and osmotic coefficients were calculated. ► The apparent properties were fitted using a Redlich–Meyer type equation. ► The osmotic coefficients were correlated using the Extended Pitzer model. -- Abstract: In this work, physical properties (densities and speeds of sound) for the binary systems {1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate} were experimentally measured from T = (293.15 to 323.15) K and at atmospheric pressure. These data were used to calculate the apparent molar volume and apparent molar isentropic compression which were fitted to a Redlich–Meyer type equation. This fit was used to obtain the corresponding apparent molar properties at infinite dilution. On the other hand, the osmotic and activity coefficients and vapor pressures of these binary mixtures were also determined at T = 323.15 K using the vapor pressure osmometry technique. The Extended Pitzer model of Archer was employed to correlate the experimental osmotic coefficients. From the parameters obtained in the correlation, the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated

  15. Thermodynamics of the first and second proton dissociations from aqueous L-aspartic acid and L-glutamic acid at temperatures from (278.15 to 393.15) K and at the pressure 0.35 MPa: Apparent molar heat capacities and apparent molar volumes of zwitterionic, protonated cationic, and deprotonated anionic forms at molalities from (0.002 to 1.0) mol . kg{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Ziemer, S.P. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Woolley, E.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States)]. E-mail: earl_woolley@byu.edu

    2007-04-15

    We have measured the densities of aqueous solutions of L-aspartic acid, L-glutamic acid, and equimolal solutions of these two amino acids with HCl and with NaOH at temperatures 278.15 {<=} T/K {<=} 368.15, at molalities 0.002 {<=} m/mol . kg{sup -1} {<=} 1.0 as solubity of the solutes allowed, and at p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 {<=} T/K {<=} 393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes V {sub {phi}} and the heat capacities to calculate apparent molar heat capacities C {sub p,{phi}} for these solutions. We used our results and values from the literature for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change {delta}{sub r} C {sub p,m}(T, m) for ionization of water to calculate parameters for {delta}{sub r} C {sub p,m}(T, m) for the first two proton dissociations from each of the protonated aqueous cationic amino acids. We used Young's Rule and integrated these results iteratively to account for the effects of equilibrium speciation and chemical relaxation on V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m). This procedure gave parameters for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for L-aspartinium and L-glutaminium chlorides and for monosodium L-aspartate and L-glutamate which modeled our observed results within experimental uncertainties. We report values for {delta}{sub r} C {sub p,m}, {delta}{sub r} H {sub m}, pQ {sub a}, {delta}{sub r} S {sub m}, and {delta}{sub r} V {sub m} for the first and second proton dissociations from protonated aqueous L-aspartic acid and L-glutamic acid as functions of T and m.

  16. Ab initio molar volumes and Gaussian radii.

    Science.gov (United States)

    Parsons, Drew F; Ninham, Barry W

    2009-02-12

    Ab initio molar volumes are calculated and used to derive radii for ions and neutral molecules using a spatially diffuse model of the electron distribution with Gaussian spread. The Gaussian radii obtained can be used for computation of nonelectrostatic ion-ion dispersion forces that underlie Hofmeister specific ion effects. Equivalent hard-sphere radii are also derived, and these are in reasonable agreement with crystalline ionic radii. The Born electrostatic self-energy is derived for a Gaussian model of the electronic charge distribution. It is shown that the ionic volumes used in electrostatic calculations of strongly hydrated cosmotropic ions ought best to include the first hydration shell. Ionic volumes for weakly hydrated chaotropic metal cations should exclude electron overlap (in electrostatic calculations). Spherical radii are calculated as well as nonisotropic ellipsoidal radii for nonspherical ions, via their nonisotropic static polarizability tensors. PMID:19140766

  17. Excess Molar Volume of Binary Systems Containing Mesitylene

    Directory of Open Access Journals (Sweden)

    Morávková, L.

    2013-05-01

    Full Text Available This paper presents a review of density measurements for binary systems containing 1,3,5-trimethylbenzene (mesitylene with a variety of organic compounds at atmospheric pressure. Literature data of the binary systems were divided into nine basic groups by the type of contained organic compound with mesitylene. The excess molar volumes calculated from the experimental density values have been compared with literature data. Densities were measured by a few experimental methods, namely using a pycnometer, a dilatometer or a commercial apparatus. The overview of the experimental data and shape of the excess molar volume curve versus mole fraction is presented in this paper. The excess molar volumes were correlated by Redlich–Kister equation. The standard deviations for fitting of excess molar volume versus mole fraction are compared. Found literature data cover a huge temperature range from (288.15 to 343.15 K.

  18. Partial molar volume and partial molar compressibility of four homologous {alpha}-amino acids in aqueous sodium fluoride solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopal, K., E-mail: krpal25@yahoo.co [Department of Physics, Government College of Engg., Tirunelveli 627 007, Tamilnadu (India); Edwin Gladson, S., E-mail: aseg_win@rediffmail.co [Department of Physics, St. Xavier' s Catholic College of Engg., Chunkankadai 629 003, Tamilnadu (India)

    2011-06-15

    Research highlights: Partial molar volume indicates strong solute-cosolute interaction in the NaF solution. Partial molar compressibility results compliment partial molar volume results. Hydration number proves that sodium fluoride has dehydration effect on amino acids. Interactions between sodium fluoride and (NH{sub 3}{sup +},COO{sup -}) group of amino acid are stronger. - Abstract: Density and ultrasonic speed of four amino acids (glycine, L-alanine, L-valine, and L-leucine) in aqueous sodium fluoride solutions {l_brace}(0.1 to 0.5) M{r_brace} have been measured at T = (308.15, 313.15, and 318.15) K. Apparent molar volumes (V{sub {phi}}), partial molar volumes (V{sub {phi}}{sup 0}), transfer volumes ({Delta}V{sub {phi}}{sup 0}) and hydration number (n{sub H}) are evaluated using density data. Adiabatic compressibility ({beta}{sub s}), change ({Delta}{beta}{sub s}), and relative change in compressibility ({Delta}{beta}{sub s}/{beta}{sub 0}), apparent molar compressibility (K{sub {phi}}), partial molar compressibility (K{sub {phi}}{sup 0}), transfer compressibility ({Delta}K{sub {phi}}{sup 0}), and hydration number (n{sub H}) have been calculated using ultrasonic speed data. The linear correlation of V{sub {phi}}{sup 0},{Delta}V{sub {phi}}{sup 0},K{sub {phi}}{sup 0} and {Delta}K{sub {phi}}{sup 0} for a homologous series of amino acids have been used utilised to calculate the contribution of charged end groups (NH{sub 3}{sup +}, COO{sup -}), CH{sub 2} group and other alkyl chain of the amino acids. The analysis shows that the ion-ion interactions are much stronger than ion-hydrophobic interactions over the entire concentration range of sodium fluoride. It is observed that sodium fluoride has a strong dehydration effect on amino acids.

  19. Density and molar volume studies of phosphate glasses

    Directory of Open Access Journals (Sweden)

    Chanshetti U.B.

    2011-01-01

    Full Text Available The density and molar volume of some phosphate glasses (xNa2O•(100-xP2O5, x = 30, 35, 40, 45, 50; xB2O3•(1-xNaPO3, x = 5, 10, 15, 20, 25; xNa2O•(30-x K2O•10Al2O3• 25B2O3•35P2O5, x= 5, 10, 15, 20, 25 glasses were determined, in order to study their structure. The density of the glasses increased while their molar volume values decreases with the increase of sodium oxide content in phosphate glasses. The results obtained could be correlated to several factors such as the polarization, the field strengths and the ionic radii of the different incorporated cations.

  20. Excess Molar Volume of Binary Systems Containing Mesitylene

    OpenAIRE

    Morávková, L. (Lenka); Sedláková, Z.

    2013-01-01

    This paper presents a review of density measurements for binary systems containing 1,3,5-trimethylbenzene (mesitylene) with a variety of organic compounds at atmospheric pressure. Literature data of the binary systems were divided into nine basic groups by the type of contained organic compound with mesitylene. The excess molar volumes calculated from the experimental density values have been compared with literature data. Densities were measured by a few experimental methods, namely using a ...

  1. The molar hydrodynamic volume changes of factor VIIa due to GlycoPEGylation

    DEFF Research Database (Denmark)

    Plesner, Bitten; Westh, Peter; Hvidt, Søren;

    2011-01-01

    The effects of GlycoPEGylation on the molar hydrodynamic volume of recombinant human rFVIIa were investigated using rFVIIa and two GlycoPEGylated recombinant human FVIIa derivatives, a linear 10 kDa PEG and a branched 40 kDa PEG, respectively. Molar hydrodynamic volumes were determined by capillary......, that the molar hydrodynamic volume of the conjugated protein is not just an addition of the molar hydrodynamic volume of the PEG and the protein. The molar hydrodynamic volume of the GlycoPEGylated protein is larger than the volume of its composites. These results suggest that both the linear and the branched...

  2. Densities, Excess Molar Volumes, and Thermal Expansion Coefficients of Aqueous Aminoethylethanolamine Solutions at Temperatures from 283.15 to 343.15 K.

    Science.gov (United States)

    Stec, Marcin; Tatarczuk, Adam; Spiewak, Dariusz; Wilk, Andrzej

    2014-01-01

    The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15-343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich-Kister equation. Temperature dependences of the Redlich-Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian-Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. PMID:24899753

  3. Partial molar volume of L-Valine in water under high pressure

    Science.gov (United States)

    Sawamura, Seiji

    2013-06-01

    Partial molar volume of L-valine in water was estimated up to 400 MPa from pressure coefficient of the solubility of the solute and molar volume of solid valine. The former was measured in a previous paper and the latter was measured in this article using a piston-cylinder typed cell. The partial molar volume increased with pressure and a maximum was observed around 250 MPa. It was compared with other amino acids.

  4. Measurement and Correlation on Viscosity and Apparent Molar Volume of Ternary System for L-ascorbic Acid in Aqueous D-Glucose and Sucrose Solutions%L-抗坏血酸在葡萄糖和蔗糖溶液中的黏度及其热力学性质的研究

    Institute of Scientific and Technical Information of China (English)

    赵长伟; 马沛生

    2003-01-01

    Viscosities and densities at several temperatures from 293.15 K to 313.15 K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations. The parameters of density, viscosity coefficient B and partial molar volume are calculated by regression. The experimental results show that densities and viscosities decrease as temperature increases at the same solute and solvent (glucose and sucrose aqueous solution) concentrations, and increase with concentration of glucose and sucrose at the same solute concentration and temperature. B increases with concentration of glucose and sucrose and temperature. L-ascorbic acid is structure-breaker or structure-making for the glucose and sucrose aqueous solutions. Furthermore, the solute-solvent interactions in ternary systems of water-glucose-electrolyte and water-sucrose-electrolyte are discussed.

  5. Partial molar volumes and partial molar adiabatic compressibilities of a short chain perfluorosurfactant: Sodium heptafluorobutyrate in aqueous solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Elena [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Ruso, Juan M. [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)]. E-mail: faruso@usc.es; Prieto, Gerardo [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Sarmiento, Felix [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

    2005-12-15

    Density and ultrasound measurements of sodium heptafluorobutyrate in aqueous solutions at T = (283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K have been obtained. From these results partial molar volumes and isentropic partial molar adiabatic compressibilities were calculated. Deviations from the Debye-Hueckel limiting law provide evidence for limited association at lower concentrations. The change of the partial molar volume and isentropic partial molar adiabatic compressibility upon aggregation was calculated. Variations of the change of partial molar volumes and isentropic partial molar adiabatic compressibility upon aggregation are discussed in terms of temperature.

  6. Molar Volume Analysis of Molten Ni-Al-Co Alloy by Measuring the Density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; FANG Liang; FU Yuechao; YANG Lingchuan

    2004-01-01

    The density of molten Ni-Al-Co alloys was measured in the temperature range of 1714~1873K using a modified pycnometric method, and the molar volume of molten alloys was analyzed. The density of molten Ni-Al-Co alloys was found to decrease with increasing temperature and Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys increases with increasing Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys shows a negative deviation from the linear molar volume.

  7. Pressure Dependence of Molar Volume near the Melting Point in Benzene

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The pressure dependence of the molar volume was at constant temperatures close to the melting point in benzene. The molar volume of benzene was calculated using experimental data for the thermal expansivity for constant temperatures of 25℃, 28.5℃, 40℃, and 51℃ at various pressures for both the solid and liquid phases. The predictions are in good agreement with the observed volumes in both the solid and liquid phases of benzene. The predicted values of the molar volume for a constant temperature of 28.5℃ in the liquid phase of benzene agree well with experimental data in the literature.

  8. Application of ERAS-model and Prigogine-Flory-Patterson theory to excess molar volumes for ternary mixtures of (2-chlorobutane + butylacetate + isobutanol) at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Khanlarzadeh, K. [Department of Physical Chemistry, Faculty of Chemistry, University of Bu-Ali Sina, Hamedan (Iran, Islamic Republic of); Iloukhani, H., E-mail: iloukhani@basu.ac.ir [Department of Physical Chemistry, Faculty of Chemistry, University of Bu-Ali Sina, Hamedan (Iran, Islamic Republic of)

    2011-11-15

    Highlights: > Density of ternary and three binary mixtures of (2-chlorobutane + butylacetate + isobutanol) determined. > Excess molar volume, partial molar volume and apparent molar volume were calculated. > Excess molar volume was correlated as a function of mole fraction by using the Redlich-Kister and Cibulka equation for all mixtures. > The experimental results have been used to test the applicability of the ERAS-model and PFP theory. - Abstract: Densities of the ternary mixture consisting of {l_brace}2-chlorobutane (1) + butylacetate (2) + isobutanol (3){r_brace} and related binary mixtures were measured over the whole range of composition at T = 298.15 K and ambient pressure. Excess molar volumes V{sub m}{sup E} for the mixtures were derived and correlated as a function of mole fraction by using the Redlich-Kister and the Cibulka equations for binary and ternary mixtures, respectively. From the experimental data, partial molar volumes, V-bar{sub m,i} excess partial molar volumes, V-bar{sub i}{sup E} partial molar volumes at infinite dilution V-bar{sub m,i}{sup 0} and apparent molar volumes V-bar{sub {phi},i} were also calculated. For all binary mixtures over the entire range of mole fractions V{sub m}{sup E} data are positive. The experimental results of the constituted binary mixtures have been used to test the applicability of the extended real associated solution (ERAS-model) and Prigogine-Flory-Paterson (PFP) theory.

  9. Effect of Molecular Size of Solutes on Their Partial Molar Volumes in Supercritical n-Pentane

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The densities of n-pentane, methane-n-pentane, propane-n-pentane, n-heptane-n-pentane, and n-decane-n-pentane binary mixtures were determined at 476.5K in the pressure range from 2 to 5 MPa. The partial molar volumes of the solutes in n-pentane were calculated using the density data. It was found that the partial molar volumes of methane and propane are positive , while those of n-heptane and n-decane are negative.

  10. Deptermination of Partial Molar Volumes of EPA and DHA Ethyl Esters in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    MeiHUANG; XianDaWANG; 等

    2002-01-01

    The use of supercritical-fluid shromatogrphy for determining partial molar volumes of ethyl esters of cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosa-hexaenoic acid(DHA) in supercritical carbon dioxide is presented and discussed. Partial molar volumes of EPA and DHA esters are obtained from the variation of the retention properties with the density of mobile phase at 313.15K,323.15K,333.15K and in the pressure range from 9 MPa to 21 MPa.

  11. Determination of Partial Molar Volumes of EPA and DHA Ethyl Esters in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The use of supercritical-fluid chromatography for determining partial molar volumes of ethyl esters of cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis -4,7,10,13,16,19- docosa-hexaenoic acid (DHA) in supercritical carbon dioxide is presented and discussed. Partial molar volumes of EPA and DHA esters are obtained from the variation of the retention properties with the density of mobile phase at 313.15 K, 323.15 K, 333.15 K and in the pressure range from 9 MPa to 21 MPa.

  12. Excess Molar Volumes and Viscosities of Binary Mixture of Diethyl Carbonate+Ethanol at Different Temperatures

    Institute of Scientific and Technical Information of China (English)

    MA Peisheng; LI Nannan

    2005-01-01

    The purpose of this work was to report excess molar volumes and dynamic viscosities of the binary mixture of diethyl carbonate (DEC)+ethanol. Densities and viscosities of the binary mixture of DEC+ethanol at temperatures 293.15 K-343.15 K and atmospheric pressure were determined over the entire composition range. Densities of the binary mixture of DEC+ethanol were measured by using a vibrating U-shaped sample tube densimeter. Viscosities were determined by using Ubbelohde suspended-level viscometer. Densities are accurate to 1.0×10-5 g·cm-3, and viscosities are reproducible within ±0.003 mPa·s. From these data, excess molar volumes and deviations in viscosity were calculated. Positive excess molar volumes and negative deviations in viscosity for DEC+ethanol system are due to the strong specific interactions.All excess molar vo-lumes and deviations in viscosity fit to the Redlich-Kister polynomial equation.The fitting parameters were presented,and the average deviations and standard deviations were also calculated.The errors of correlation are very small.It proves that it is valuable for estimating densities and viscosities of the binary mixture by the correlated equation.

  13. Excess molar volumes for CO sub 2 -CH sub 4 -N sub 2 mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, J.C. (Oak Ridge National Lab., TN (United States) Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Geological Sciences); Blencoe, J.G.; Joyce, D.B. (Oak Ridge National Lab., TN (United States)); Bodnar, R.J. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Geological Sciences)

    1992-01-01

    Vibrating-tube densimetry experiments are being performed to determine the excess molar volumes of single-phase CO{sub 2}-CH{sub 4}-N{sub 2} gas mixtures at pressures as high as 3500 bars and temperatures up to 500{degrees}C. In our initial experiments, we determined the P-V-T properties of: (1) CO{sub 2}-CH{sub 4}, CO{sub 2}N{sub 2}, CH{sub 4}-N{sub 2}, and CO{sub 2}-CH{sub 4}-N{sub 2} mixtures at 1000 bars. 50 {degrees}C: and (2) CO{sub 2}-CH{sub 4} mixtures from 100 to 1000 bars at 100{degrees}C. Excess molar volumes in the binary subsystems are very accurately represented by two-parameter Margules equations. Experimentally determined excess molar volumes are in fair to poor agreement with predictions from published equations of state. Geometric projection techniques based on binary system data yield from published equations of state. Geometric projection techniques based on binary system data yield calculated excess molar volume for CO{sub 2}-CH{sub 4}-N{sub 2} mixtures that are in good agreement with our experimental data. 7 refs., 8 figs.

  14. Excess molar volumes and isentropic compressibilities of binary liquid mixtures containing n-alkanes at 298.15 K

    Indian Academy of Sciences (India)

    V Vyas; T Nautiyal

    2002-10-01

    Excess molar volumes (E) and deviation in isentropic compressibilities (s) have been investigated from the density and speed of sound measurements of six binary liquid mixtures containing -alkanes over the entire range of composition at 298.15 K. Excess molar volume exhibits inversion in sign in one binary mixture, i.e., n-heptane + n-hexane. Remaining five binary mixtures, n-heptane + toluene, cyclohexane + n-heptane, cyclohexane + n-hexane, toluene + nhexane and n-decane + n-hexane show negative excess molar volumes over the whole composition range. However, the large negative values of excess molar volume becomes dominant in toluene + n-hexane mixture. Deviation in isentropic compressibility is negative over the whole range of composition in the case of all the six binary mixtures. Existence of specific intermolecular interactions in the mixtures has been analyzed in terms of excess molar volume and deviation in isentropic compressibility.

  15. Excess Molar Volume of Binary Mixtures of Methylheptenone+Alkanols at 298.15 K

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Excess molar volume(VE) data on binary liquid mixtures of methylheptenone (MHO) with methanol, ethanol, n-propanol or n-butanol have been determined from the density measurements at 298.15 K and atmospheric pressure. The values of VE in all the systems over the entire composition range are quantified by the Redlich-Kister equation. The effects of the chain length of alkanols on VE are discussed.

  16. MEASURED DENSITIES, REFRACTIVE INDICES, EXCESS MOLAR VOLUMES AND DEVIATIONS CALCULATED FROM MOLAR REFRACTION OF THE BINARY MIXTURE OF ETHANOL + 1-NONANOL AND TERNARY MIXTURE ETHANOL + 1-NONANOL + WATER AT 293.15 K

    Directory of Open Access Journals (Sweden)

    Mehmet MAHRAMANLIOĞLU

    2000-03-01

    Full Text Available Densities, and refractive indices were measured for the binary system ethanol + 1-nonanol and ternary system ethanol + 1-nonanol + water at 293.15 K. The excess molar volumes, and the deviations molar refraction were calculated for binary and ternary system. Redlich-Kister type equation was fitted to the excess molar volumes and, the deviations from a mole fraction average of the molar refraction, and the values of coefficients were calculated

  17. Hydrogen bonding interactions between ethylene glycol and water: density, excess molar volume, and spectral study

    Institute of Scientific and Technical Information of China (English)

    ZHANG JianBin; ZHANG PengYan; MA Kai; HAN Fang; CHEN GuoHua; WEI XiongHui

    2008-01-01

    Studies of the density and the excess molar volume of ethylene glycol (EG)-water mixtures were carried out to illustrate the hydrogen bonding interactions of EG with water at different temperatures, The re-sults suggest that a likely complex of 3 ethylene glycol molecules bonding with 4 water molecules in an ethylene glycol-water mixture (EGW) is formed at the maximal excess molar volume, which displays stronger absorption capabilities for SO2 when the concentration of SO2 reaches 400×106 (volume ratio) in the gas phase. Meanwhile, FTIR and UV spectra of EGWs were recorded at various EG concentra-tions to display the hydrogen bonding interactions of EG with water. The FTIR spectra show that the stretching vibrational band of hydroxyl in the EGWs shifts to a lower frequency and the bending vibra-tional band of water shifts to a higher frequency with increasing the EG concentration, respectively. Furthermore, the UV spectra show that the electron transferring band of the hydroxyl oxygen in EG shows red shift with increasing the EG concentration. The frequency shifts in FTIR spectra and the shifts of absorption bands in UV absorption spectra of EGWs are interpreted as the strong hydrogen bonding interactions of the hydrogen atoms in water with the hydroxyl oxygen atoms of EG.

  18. Apparent Molal Volumes of Sodium Fluoride in Mixed Aqueous-Ethanol Solvents

    Directory of Open Access Journals (Sweden)

    E. Gomaa

    2010-09-01

    Full Text Available The densities of different molal concentrations of sodium fluoride at ethanol-water mixtures, as solvent, have been measured over the whole composition range at three different temperatures, 293.15, 303.15 and 313.15oK. From the measured densities, the apparent and limiting molal volumes of the electrolytes have been evaluated. The limiting molal volumes for sodium and fluoride ions were estimated by splitting the ionic contributions as an asymmetric assumption.

  19. A Structural Molar Volume Model for Oxide Melts Part III: Fe Oxide-Containing Melts

    Science.gov (United States)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    As part III of this series, the model is extended to iron oxide-containing melts. All available experimental data in the FeO-Fe2O3-Na2O-K2O-MgO-CaO-MnO-Al2O3-SiO2 system were critically evaluated based on the experimental condition. The variations of FeO and Fe2O3 in the melts were taken into account by using FactSage to calculate the Fe2+/Fe3+ distribution. The molar volume model with unary and binary model parameters can be used to predict the molar volume of the molten oxide of the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-FeO-Fe2O3-Al2O3-SiO2 system in the entire range of compositions, temperatures, and oxygen partial pressures from Fe saturation to 1 atm pressure.

  20. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

    Science.gov (United States)

    Tan, Ming-Liang; Miller, Benjamin T.; Te, Jerez; Cendagorta, Joseph R.; Brooks, Bernard R.; Ichiye, Toshiko

    2015-02-01

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has "brittle" hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water.

  1. Calculation of partial molar volume of components in supercritical ammonia synthesis system

    Institute of Scientific and Technical Information of China (English)

    Cunwen WANG; Chuanbo YU; Wen CHEN; Weiguo WANG; Yuanxin WU; Junfeng ZHANG

    2008-01-01

    The partial molar volumes of components in supercritical ammonia synthesis system are calculated in detail by the calculation formula of partial molar volume derived from the R-K equation of state under different conditions. The objectives are to comprehend phase beha-vior of components and to provide the theoretic explana-tion and guidance for probing novel processes of ammonia synthesis under supercritical conditions. The conditions of calculation are H2/N2= 3, at a concentra-tion of NH3 in synthesis gas ranging from 2% to 15%, Concentration of medium in supercritical ammonia syn-thesis system ranging from 20% to 50%, temperature ran-ging from 243 K to 699 K and pressure ranging from 0.1 MPa to 187 MPa. The results show that the ammonia synthesis system can reach supercritical state by adding a suitable supercritical medium and then controlling the reaction conditions. It is helpful for the supercritical ammonia synthesis that medium reaches supercritical state under the conditions of the corresponding total pres-sure and components near the normal temperature or near the critical temperature of medium or in the range of tem-perature of industrialized ammonia synthesis.

  2. Dependence of molar volumes and density of individual substances and solutions on temperature and pressure

    International Nuclear Information System (INIS)

    A three-parameter equation, describing with a high accuracy the density and reduced (molar, specific) volumes (V) of individual substances and solutions in any aggregate state as the function of temperature and pressure, is suggested. By the equation differentiation analytic expressions for actual coefficient of isobaric thermal expansion and coefficient of isothermal compression of substances and solutions are obtained. The calculated and table values of the coefficients for water under atmospheric pressure and temperatures of 283-353K are compared. Applicability of the equation V(T, p) is illustrated using concrete examples, i.e. Th, U, Pu, uranium fluorides and nitrates, TBP and other substances, essential for the practice of extraction reprocessing of irradiated fuel and other processes of nuclear fuel cycle

  3. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Ming-Liang; Te, Jerez; Cendagorta, Joseph R. [Department of Chemistry, Georgetown University, Washington, District of Columbia 20057 (United States); Miller, Benjamin T.; Brooks, Bernard R. [Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20892 (United States); Ichiye, Toshiko, E-mail: ti9@georgetown.edu [Department of Chemistry, Georgetown University, Washington, District of Columbia 20057 (United States); Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, Maryland 20892 (United States)

    2015-02-14

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol V{sub E} as a function of ethanol mole fraction X{sub E} is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has “brittle” hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water.

  4. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

    International Nuclear Information System (INIS)

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol VE as a function of ethanol mole fraction XE is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has “brittle” hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water

  5. Molar volume, thermal expansivity and isothermal compressibility of trans-decahydronaphthalene up to 200MPa and 446K

    Institute of Scientific and Technical Information of China (English)

    Zhu Hu-Gang; Liu Zhi-Hua; Tian Yi-Ling; Xue Yuan; Yin Liang

    2005-01-01

    The molar volume isotherms of trans-decahydronaphthalene (C10H18) between 293 and 446 K and at pressures from 10 to 200 MPa have been determined. A modified Tait equation of state is used to fit each experimental molar volume isotherm with a maximum average deviation of 0.029%. The thermal expansivity (cubic expansion coefficient) α and isothermal compressibility κ were determined by fitting the slopes of the isobaric curves and isotherms, respectively.The coefficients in the equation Vm = C1 + C2T + C3T2 - C4p - C5pT have been fitted with an average deviation of 1.03%.

  6. Excess molar volumes for CO{sub 2}-CH{sub 4}-N{sub 2} mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, J.C. [Oak Ridge National Lab., TN (United States)]|[Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Geological Sciences; Blencoe, J.G.; Joyce, D.B. [Oak Ridge National Lab., TN (United States); Bodnar, R.J. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Geological Sciences

    1992-04-01

    Vibrating-tube densimetry experiments are being performed to determine the excess molar volumes of single-phase CO{sub 2}-CH{sub 4}-N{sub 2} gas mixtures at pressures as high as 3500 bars and temperatures up to 500{degrees}C. In our initial experiments, we determined the P-V-T properties of: (1) CO{sub 2}-CH{sub 4}, CO{sub 2}N{sub 2}, CH{sub 4}-N{sub 2}, and CO{sub 2}-CH{sub 4}-N{sub 2} mixtures at 1000 bars. 50 {degrees}C: and (2) CO{sub 2}-CH{sub 4} mixtures from 100 to 1000 bars at 100{degrees}C. Excess molar volumes in the binary subsystems are very accurately represented by two-parameter Margules equations. Experimentally determined excess molar volumes are in fair to poor agreement with predictions from published equations of state. Geometric projection techniques based on binary system data yield from published equations of state. Geometric projection techniques based on binary system data yield calculated excess molar volume for CO{sub 2}-CH{sub 4}-N{sub 2} mixtures that are in good agreement with our experimental data. 7 refs., 8 figs.

  7. Partial molar volume of paracetamol in water, 0.1 M HCl and 0.154 M NaCl at T = (298.15, 303.15, 308.15 and 310.65) K and at 101.325 kPa

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Javed [Department of Chemistry, Quaid-i-Azam University, Islamabad, Capital 54320 (Pakistan)]. E-mail: mjiqauchem@yahoo.com; Malik, Qaisar Mahmood [Department of Chemistry, Quaid-i-Azam University, Islamabad, Capital 54320 (Pakistan)]. E-mail: qaisar_@hotmail.com

    2005-12-15

    The apparent molar volume of paracetamol (4-acetamidophenol) in water, 0.1 M HCl and 0.154 M NaCl as solvents at (298.15, 303.15, 308.15 and 310.65) K temperatures and at a pressure of 101.325 kPa were determined from the density data obtained with the help of a vibrating-tube Anton Paar DMA-48 densimeter. The partial molar volume, V {sub m}, of paracetamol in these solvents at different temperatures was evaluated by extrapolating the apparent molar volume versus molality plots to m = 0. In addition, the partial molar expansivity, E {sup .}, the isobaric coefficient of thermal expansion, {alpha} {sub p}, and the interaction coefficient, S {sub v}, have also been computed. The expansivity data show dependence of E {sup .} values on the structure of the solute molecules.

  8. Experimental density data and excess molar volumes of coconut biodiesel + n-hexadecane and coconut biodiesel + diesel at different temperatures

    Directory of Open Access Journals (Sweden)

    F. M. R. Mesquita

    2014-06-01

    Full Text Available The density of the pure component (n-hexadecane, pure pseudo-components (coconut biodiesel and diesel and pseudo-binary mixtures of coconut biodiesel with n-hexadecane (or + diesel were measured at temperatures 293.15, 313.15, 333.15, 353.15 and 373.15 K and atmospheric pressure, over the entire composition range (mole fractions from 0.1 to 0.9, with a step de 0.1. Densities were determined using an Anton Paar SVM 3000 viscodensimeter. Experimental density values decreased with the increase of the temperature. The excess molar volumes of the pseudo-binary mixtures were calculated by using the experimental values of density. Excess molar volumes were correlated with the Redlich-Kister polynomial expansions. Excess molar volumes show positive and negative values in the two systems studied. Excess partial volumes at infinite dilution were calculated for coconut biodiesel, n-hexadecane and diesel in the mixtures studied.

  9. Excess molar volumes of 1,3 propanediol + (C1-C5 alkan-1-ols: Application of cubic EOS

    Directory of Open Access Journals (Sweden)

    Almasi Mohammad

    2012-01-01

    Full Text Available Densities of the binary mixtures consist of methanol, ethanol, 1- propanol, 1-butanol and 1-pentanol with 1,3 Propanediol were measured at temperatures (293.15, 298.15, 303.15 and 313.15 K and atmospheric pressure. Measurements have been made over the full range of compositions and for the pure compounds by using a vibrating tube densimeter. Excess molar volumes have been obtained from these experimental results and were fitted to a Redlich-Kister type expansion. The results were interpreted in terms of molecular interactions and structural factors of the alcohols. It was observed that an increase of the alcohol carbon chain length led to lower interactions on mixing. The Peng-Robinson-Stryjek-Vera (PRSV equation of state has been used to correlate the binary excess molar volumes.

  10. 293.15 K到333.15 K温度下一些氨基酸及其相应基团水溶液中的偏摩尔体积研究%Studies on Partial Molar Volumes of Some Amino Acids and Their Groups in Aqueous Solutions from 293.15 K to 333.15 K

    Institute of Scientific and Technical Information of China (English)

    赵长伟; 马沛生; 夏淑倩

    2004-01-01

    Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine,L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.15 K to 333.15K. These data are used to calculate the apparent molar volume V and infinite dilution apparent molar volume V0 (partial molar volume). Data of five amino acids are used to correlate partial molar volume V0 using group contribution method to estimate the contributions of the zwitterionic end groups (NH3+,COO-) and CH2group, OH group, CNHNHNH2 group and C6H5(phenyl) group of amino acids. The results show that V0 values for all kinds of groups of amino acids studied increase with increase of temperature except those for CH2 group,which are almost constant within the studied temperature range. Data of other amino acids, L-valine, L-isoleucine and L-threonine, are chosen for comparison with the predicted partial molar volume V0 using the group additivity parameters obtained. The results confirm that this group additivity method has excellent predictive utility.

  11. Hydrogen bonding interactions between ethylene glycol and water:density,excess molar volume,and spectral study

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studies of the density and the excess molar volume of ethylene glycol (EG)-water mixtures were carried out to illustrate the hydrogen bonding interactions of EG with water at different temperatures. The re-sults suggest that a likely complex of 3 ethylene glycol molecules bonding with 4 water molecules in an ethylene glycol-water mixture (EGW) is formed at the maximal excess molar volume,which displays stronger absorption capabilities for SO2 when the concentration of SO2 reaches 400×10?6 (volume ratio) in the gas phase. Meanwhile,FTIR and UV spectra of EGWs were recorded at various EG concentra-tions to display the hydrogen bonding interactions of EG with water. The FTIR spectra show that the stretching vibrational band of hydroxyl in the EGWs shifts to a lower frequency and the bending vibra-tional band of water shifts to a higher frequency with increasing the EG concentration,respectively. Furthermore,the UV spectra show that the electron transferring band of the hydroxyl oxygen in EG shows red shift with increasing the EG concentration. The frequency shifts in FTIR spectra and the shifts of absorption bands in UV absorption spectra of EGWs are interpreted as the strong hydrogen bonding interactions of the hydrogen atoms in water with the hydroxyl oxygen atoms of EG.

  12. Various estimates of Representative Volume Element sizes based on a statistical analysis of the apparent behavior of random linear composites

    OpenAIRE

    Salmi, Moncef; Auslender, François; Bornert, Michel; Fogli, Michel

    2012-01-01

    This article aims at proposing various estimates of the size of the Representative Volume Element (RVE) of random linear elastic matrix-inclusion composites. These estimates are derived from the computation of the apparent behavior of finite size volume elements (VE) by a new procedure presented in . [18] by Salmi et al. (2012) and briefly recalled. Two different points of view to define an RVE are considered: the RVE is defined as being the smallest VE required either to evaluate numerically...

  13. Apparent diffusion coefficients in GEC ESTRO target volumes for image guided adaptive brachytherapy of locally advanced cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Haack, Soeren (Dept. of Clinical Engineering, Aarhus Univ. Hospital (Denmark)), E-mail: Soeren.haack@stab.rm.dk; Morre Pedersen, Erik (Dept. of Radiology, Aarhus Sygehus, Aarhus Univ. Hospital (Denmark)); Jespersen, Sune N. (Center of Functionally Integrative Neuroscience, Aarhus Univ. Hospital (Denmark)); Kallehauge, Jesper F. (Dept. of Medical Physics, Aarhus Univ. Hospital (Denmark)); Lindegaard, Jacob Christian; Tanderup, Kari (Dept. of Oncology Aarhus Univ. Hospital (Denmark))

    2010-10-15

    Background and purpose. T2 weighted MRI is recommended for image guided adaptive brachytherapy (IGABT) in cervical cancer. Diffusion weighted imaging (DWI) and the derived apparent diffusion coefficient (ADC) may add additional biological information on tumour cell density. The purpose of this study was to evaluate the distribution of the ADC within target volumes as recommended by GEC-ESTRO: Gross Tumour Volume at BT (GTVBT), High-Risk Clinical Tumour Volume (HR-CTV) and Intermediate-Risk Clinical Target Volume (IR-CTV) and to evaluate the change of diffusion between fractions of IGABT. Material and methods. Fifteen patients with locally advanced cervical cancer were examined by MRI before their first (BT1) and second (BT2) fraction of IGABT, resulting in a total of 30 MR examinations including both T2 weighted and DWI sequences. The Apparent Diffusion Coefficient (ADC) was calculated by use of three levels of b-values (0, 600, 1000 s/mm2). ADC maps were constructed and fused with the GEC ESTRO target contours. The mean ADC value within each target volume was calculated. Furthermore, volumes of low diffusion (ADClow) were defined based on an ADC threshold of 1.2 x 10-3 mm2/s, and overlap with target volumes was evaluated. Change of ADC level in target volumes and change of ADClow volume from BT1 to BT2 was also evaluated. Results. The mean ADC was significantly lower in GTVBT than in HR-CTV (p<0.001) which again was significantly lower than in IR-CTV (p<0.001). There was no significant change of the ADClow volume or ADC level within each target structure between BT1 and BT2 (p=0.242). All three GEC-ESTRO volumes contained volumes with low diffusion. The GTVBT contained 37.2% volume of low diffusion, HR-CTV 20.3% and IR-CTV 10.8%. Conclusion. With DWI we were able to find a significant difference in ADC-values for the three different GEC ESTRO targets. This supports the assumption that the target volumes used for dose prescription in IGABT contain tissues with

  14. Partial molar volumes of organic solutes in water. XXIII. Cyclic ketones at T = (298 to 573) K and pressures up to 30 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Cibulka, Ivan, E-mail: ivan.cibulka@vscht.cz [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Simurka, Lukas; Hnedkovsky, Lubomir [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Bolotov, Alexander [Butlerov Institute of Chemistry, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008 (Russian Federation)

    2011-07-15

    Research highlights: > In this study we examine standard molar volumes of aqueous cyclic ketones. > State parameters of measurements were (298 to 573) K and pressures up to 30 MPa. > Differences in behavior of monoketones and cyclohexane-1,4-dione were observed. > Group contribution method was designed and examined. - Abstract: Density data for dilute aqueous solutions of four cyclic ketones (cyclopentanone, cyclohexanone, cycloheptanone, and cyclohexane-1,4-dione) are presented together with standard molar volumes (partial molar volumes at infinite dilution) calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to T = 573 K. Experimental pressures were close to the saturated vapor pressure of water, and (15 and 30) MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter. Experimental standard molar volumes were correlated as a function of temperature and pressure using an empirical polynomial function. Contributions of the molecular structural segments (methylene and carbonyl groups) to the standard molar volume were also evaluated and analyzed.

  15. Influence of Zinc on the Surface Tension, Density and Molar Volume of (Ag-Sneut +Zn Liquid Alloys

    Directory of Open Access Journals (Sweden)

    Gąsior W.

    2016-03-01

    Full Text Available The dilatometric and maximum bubble pressure methods were applied for the measurements of the density and surface tension of liquid (Ag-Sneut +Zn lead-free solders. The experiments were carried out in the temperature range from 515 to 1223 K for the alloys of the zinc concentration equaling 0.01, 0.02, 0.04, 0.05, 0.1 and 0.2 of the mole fraction. It was found that the temperature dependence of both the density and the surface tension could be thought as linear, so they were interpreted by straight line equations. The experimental data of the molar volume of the investigated alloys were described by the polynomial dependent on the composition and temperature.

  16. Excess molar volumes and viscosities of binary mixtures of 1,2-diethoxyethane with chloroalkanes at 298 15 K

    Indian Academy of Sciences (India)

    Amalendu Pal; Rakesh Kumar Bhardwaj

    2001-06-01

    Excess molar volumes ($V^{E}_{m}$) and viscosities () of the binary mixtures of 1,2-diethoxyethane with di-, tri- and tetrachloromethane have been measured at 298.15 K and atmospheric pressure over the entire mole fraction range. The deviations in viscosities (ln) and excess energies of activation ( *) for viscous flow have been calculated from the experimental data. The Prigogine-Flory-Patterson (PFP) model has been used to calculate $V^{E}_{m}$, and the results have been compared with experimental data. The Bloomfield and Dewan model has been used to calculate viscosity coefficients and these have also been compared with experimental data for the three mixtures. The results have been discussed in terms of dipole-dipole interactions between 1,2-diethoxyethane and chloroalkanes and their magnitudes decreasing with the dipole character of the molecules. A short comparative study with results for mixtures with polyethers and chloroalkanes is also described.

  17. A study of partial molar volumes of citric acid and tartaric acid in water and binary aqueous mixtures of ethanol at various temperatures

    Indian Academy of Sciences (India)

    M L Parmar; R K Awasthi; M K Guleria

    2004-01-01

    Partial molar volumes of citric acid and tartaric acid have been determined in water and binary aqueous mixtures of ethanol (5, 10, 15, 20 and 25% by weight of ethanol) at different temperatures and acid concentrations from the solution density measurements. The data have been evaluated by using Masson equation and the obtained parameters have been interpreted in terms of solute-solvent interactions. The partial molar volumes vary with temperature as a power series of temperature. Structure making/breaking capacities of the organic acids have been inferred from the sign of [2$\\phi^{0}_{v}$/2], i.e. secondderivative of partial molar volume with respect to temperature at constant pressure. Both the organic acids behave as structure breakers in water and water + ethanol.

  18. Volumetry of human molars with flat panel-based volume CT in vitro

    NARCIS (Netherlands)

    Hannig, C.; Krieger, E.; Dullin, C.; Merten, H.A.; Attin, T.; Grabbe, E.; Heidrich, G.

    2006-01-01

    The flat panel-based volume computed tomography (fpVCT) is a new CT device applicable for experimental, three-dimensional evaluation of teeth at a resolution of about 150 microm in the high contrast region. The aim of this study was to investigate whether fpVCT was suitable for quantification of the

  19. Why Size Matters: Differences in Brain Volume Account for Apparent Sex Differences in Callosal Anatomy

    OpenAIRE

    Luders, Eileen; Toga, Arthur W.; Thompson, Paul M.

    2013-01-01

    Numerous studies have demonstrated a sexual dimorphism of the human corpus callosum. However, the question remains if sex differences in brain size, which typically is larger in men than in women, or biological sex per se account for the apparent sex differences in callosal morphology. Comparing callosal dimensions between men and women matched for overall brain size may clarify the true contribution of biological sex, as any observed group difference should indicate pure sex effects. We thus...

  20. A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.

    Science.gov (United States)

    Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

    2014-06-28

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase. PMID:24985659

  1. A molecular dynamics study of ambient and high pressure phases of silica: structure and enthalpy variation with molar volume.

    Science.gov (United States)

    Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

    2014-06-28

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

  2. Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes

    Science.gov (United States)

    Chiou, C.T.; Schmedding, D.W.; Manes, M.

    2005-01-01

    A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.

  3. Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

    Directory of Open Access Journals (Sweden)

    A. Asa-Awuku

    2008-02-01

    Full Text Available In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH42SO4 in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH42SO4. From our analysis, average thermodynamic properties (i.e, molar volume are determined for samples using our newly developed Köhler Theory Analysis (KTA method. The molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol−1 and 780±231 g mol−1, respectively. KTA also suggests that the relative proportion (in moles of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

  4. Pressure-volume-temperature and excess molar volume prediction of amorphous and crystallizable polymer blends by equation of state

    Institute of Scientific and Technical Information of China (English)

    Fakhri Yousefi; Hajir Karimi; Maryam Gomar

    2015-01-01

    In this work the statistical mechanical equation of state was developed for volumetric properties of crystal ine and amorphous polymer blends. The Ihm–Song–Mason equations of state (ISMEOS) based on temperature and density at melting point (Tm andρm) as scaling constants were developed for crystalline polymers such as poly(propylene glycol)+poly(ethylene glycol)-200 (PPG+PEG-200), poly(ethylene glycol) methyl ether-300 (PEGME-350)+PEG-200 and PEGME-350+PEG-600. Furthermore, for amorphous polymer blends con-taining poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)+polystyrene (PS) and PS+poly(vinylmethylether) (PVME), the density and surface tension at glass transition (ρg andγg) were used for estimation of second Virial coefficient. The calculation of second Virial coefficients (B2), effective van der Waals co-volume (b) and correction factor (α) was required for judgment about applicability of this model. The obtained results by ISMEOS for crys-talline and amorphous polymer blends were in good agreement with the experimental data with absolute aver-age deviations of 0.84%and 1.04%, respectively.

  5. A molecular dynamics study of ambient and high pressure phases of silica: Structure and enthalpy variation with molar volume

    Science.gov (United States)

    Rajappa, Chitra; Sringeri, S. Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J.

    2014-06-01

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume—for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

  6. Thermodynamic properties of n-alkoxyethanols + organic solvent mixtures XVI. Excess molar volumes at 298.15 K for 2-alkoxyethanol + n-polyether systems

    International Nuclear Information System (INIS)

    Excess molar volumes (VmE) at 298.15 K and atmospheric pressure for 2-methoxyethanol or 2-butoxyethanol + 2,5-dioxahexane, +2,5,8-trioxanonane, +3,6,9-trioxaundecane, +5,8,11-trioxapentadecane, or +2,5,8,11,14-pentaoxapentadecane, or for 2-ethoxyethanol + 2,5,8-trioxanonane, +3,6,9-trioxaundecane, or +5,8,11-pentaoxapentadecane have been obtained from densities measured with and Anton-Paar DMA 602 vibrating-tube densimeter. They are usually small in absolute value. It is due to a compensation between positive and negative contributions to the excess molar volume. For example, free volume effects present in solutions with the pentaether are compensated by the positive contribution to VmE from the rupture of dipole-dipole interactions between ether molecules

  7. Measurements of Enthalpy Change of Reaction of Formation, Molar Heat Capacity and Constant-Volume Combustion Energy of Solid Complex Yb(Et2dtc)3(phen)

    Institute of Scientific and Technical Information of China (English)

    Song Weiming; Hu Qilin; Chang Xuan; Chen Sanping; Xie Gang; Gao Shengli

    2006-01-01

    A ternary solid complex Yb(Et2dtc)3(phen) was obtained from the reaction of hydrous ytterbium chloride with sodium diethyldithiocarbamate (NaEt2dtc), and 1, 10-phenanthroline (o-phen·H2O) in absolute ethanol.The bonding characteristics of the complex were characterized by IR.The result shows Yb3+ bands with two sulfur atoms in the Na(Et2dtc)3 and two nitrogen atoms in the o-phen.The enthalpy change of liquid-phase reaction of formation of the complex ΔrHθm (l), was determined as being (-24.838±0.114) kJ·mol-1 at 298.15 K, by an RD-496 Ⅲ type heat conduction microcalormeter.The enthalpy change of the solid-phase reaction of formation of the complex ΔrHθm (s), was calculated as being (108.015±0.479) kJ·mol-1 on the basis of an appropriate thermochemistry cycle.The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature during the liquid-phase reaction.Fundamental parameters, the activation enthalpy, ΔHθ≠, the activation entropy, ΔSθ≠, the activation free energy, ΔGθ≠, the apparent reaction rate constant k, the apparent activation energy E, the pre-exponential constant A, and the reaction order n, were obtained by a combination of the reaction thermodynamic and kinetic equations with the data from the thermokinetic experiments.At the same time, the molar heat capacity of the complex cm, p, was determined to be (86.34±1.74) J·mol-1·K-1 by the same microcalormeter.The constant-volume combustion energy of the complex, ΔcU, was determined to be (-17954.08±8.11) kJ·mol-1 by an RBC-Ⅱ type rotating-bomb calorimeter at 298.15 K.Its standard enthalpy of combustion, ΔcHθm, and standard enthalpy of formation, ΔfHθm, were calculated to be (-17973.29±8.11) kJ·mol-1 and (-770.36±9.02) kJ·mol-1, respectively.

  8. Study of apparent molal volume and viscosity of mutual citric acid and disodium hydrogen orthophosphate aqueous systems

    Indian Academy of Sciences (India)

    Man Singh

    2006-05-01

    Fundamental properties, density () and viscosity (), of citric acid (CA) and disodium hydrogen orthophosphate (DSP) at various strengths were obtained at different temperatures. The and values were used to determine apparent molal volumes and viscosity of systems. The , and values were regressed against molality for ρ0, 0 and $V^{0}_{\\phi}$f, the limiting constants at infinite dilution ( → 0) forionic and molecular interactions. The ρ0 and $V^{0}_{\\phi}$f of aq. acids are higher than those of aq. DSP and the viscosity of DSP is higher than that of aq. CA. Examination of ρ0 and $V^{0}_{\\phi}$ functions indicates that mutual compositions of CA and DSP counterbalance concentration and temperature effects on pH in bioprocesses.

  9. Electronic polarizability of a Sm{sup 3+} ion estimated from refractive indexes and molar volumes of molten SmCl{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Iwadate, Y.; Shirao, K.; Fukushima, K. [Chiba Univ. (Japan). Faculty of Engineering

    1999-03-04

    The refractive indexes and the molar volumes of molten SmCl{sub 3} were measured by goniometry and dilatometry, respectively. The electronic polarizability of a Sm{sup 3+} ion was estimated from these data to be 1.14 x 10{sup -30}m{sup 3} according to the Clausius-Mossotti equation. The correlation between the electronic polarizability of an ion and the ionic radius was also discussed. (orig.) 23 refs.

  10. Excess molar volume of the acetonitrile + alcohol systems at 298.15 K. Part I: Density measurements for acetonitrile + methanol, + ethanol systems

    Directory of Open Access Journals (Sweden)

    SLOBODAN P. SERBANOVIC

    2002-09-01

    Full Text Available The excess molar volume VE of the binary liquid systems acetonitrile + methanol and acetonitrile + ethanol has been evaluated from density measurements at 298.15 K and at atmospheric pressure over the entire composition range. A vibrating tube densimeter, type Anton Paar DMA 55, was applied for these measurements. The Redlich–Kister equation was used to fit the experimental VE data.

  11. Buoyancy Effect of Ionic Vacancy on the Change of the Partial Molar Volume in Ferricyanide-Ferrocyanide Redox Reaction under a Vertical Gravity Field

    OpenAIRE

    Yoshinobu Oshikiri; Makoto Miura; Ryoichi Aogaki

    2013-01-01

    With a gravity electrode (GE) in a vertical gravity field, the buoyancy effect of ionic vacancy on the change of the partial molar volume in the redox reaction between ferricyanide (FERRI) and ferrocyanide (FERRO) ions was examined. The buoyancy force of ionic vacancy takes a positive or negative value, depending on whether the rate-determining step is the production or extinction of the vacancy. Though the upward convection over an upward electrode in the FERRO ion oxidation suggests the con...

  12. Excess Molar Volumes and Viscosities for Binary Mixtures of 1-Alkoxypropan-2-ols with 1-Butanol,and 2-Butanol at 298.15 K and Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    PAL Amalendu; GABA Rekha

    2007-01-01

    Excess molar volumes VEm and kinematic viscosities v have been measured as a function of composition for binary mixtures of propylene glycol monomethyl ether (1-methoxy-2-propanol),MeOCH2CH(OH)Me,propylene glycol monoethyl ether (1-ethoxy-2-propanol), EtOCH2CH(OH)Me,propylene glycol monopropyl ether (1-propoxy-2-propanol), PrOCH2CH(OH)Me, propylene glycol monobutyl ether (1-butoxy-2-propanol),BuOCH2CH(OH)Me,and propylene glycol tert-butyl ether (1-tert-butoxy-2-propanol),t-BuOCH2CH(OH)Me with 1-butanol,and 2-butanol,at 298.15 K and atmospheric pressure.The excess molar volumes are negative across the entire range of composition for all the systems with 1-butanol,and positive for the systems 2-butanol+1-methoxy-2-propanol,and +1-propoxy-2-propanol,negative for the systems 2-butanol+1-butoxy-2-propanol,and change sign for the systems 2-butanol+1-ethoxy-2-propanol,and +1-tert-butoxy-2-propanol.From the experimental data,the deviation in dynamic viscosity η from Σxiηi has been calculated.Both excess molar volumes and viscosity deviations have been correlated using a Redlich-Kister type polynomial equation by the method of least-squares for the estimation of the binary coefficients and the standard errors.

  13. Prediction of subacute infarct lesion volumes by processing apparent diffusion coefficient maps based on apparent diffusion coefficient cut-off values in patients with acute stroke

    Institute of Scientific and Technical Information of China (English)

    郭翔

    2014-01-01

    Objective To explore the feasibility of prediction of subacute infarct lesion volumes by processing ADC maps based on ADC cut-off values in patients with acute stroke.Methods MRI was performed in 20 patients with clinically diagnosed acute infarct less than 6 h after stroke onset.The MRI included a DWI and conventional MRI.The follow-up MR examinations of all the patients

  14. Partial molar volume of Ciprofloxacin in water, HCl and FeCl3.6H2O at 298.15K and 308.15K

    Directory of Open Access Journals (Sweden)

    *M. A. Jamal

    2011-06-01

    Full Text Available Partial molar volume, V0, of Ciprofloxacin in water, 0.05 mol Kg-1 hydrochloric acid and 0.05 mol Kg-1, Iron (III chloride solutions at 298.15 and 308.15 K was calculated from precision densities obtained from Density Sound Analyzer (DSA 5000. The data represent the smaller volume of drug in 0.05 mol Kg-1 Iron (III chloride solution than water and 0.05 mol Kg-1 hydrochloric acid at constant temperature. The differences in volumes are interpreted as due to hydrophobicity of solutes. Relative hydrophobicities were estimated from volumes of transfer from one media to another media. The hydrophobicity of this compound also plays a key role in the drug action. The possible mechanism of drug binding with the membrane structure is also discussed.

  15. Partial molar volumes of organic solutes in water. XXVI. 15-Crown-5 and 18-crown-6 ethers at temperatures (298 to 573) K and pressures up to 30 MPa

    International Nuclear Information System (INIS)

    Highlights: • Density data were obtained in the range T from (298 to 573) K and p up to 30 MPa. • Standard molar volumes of two crown ethers in water are presented. • Group contribution method was designed to estimate standard molar volumes of cyclic ethers. - Abstract: Densities of dilute aqueous solutions of two cyclic ethers, viz. 15-crown-5 and 18-crown-6, measured over the temperature range from (298 to 573) K and at pressures up to 30 MPa using an automated flow vibrating-tube densimeter are reported. Standard molar volumes were evaluated from the measured data. Present data were combined with those obtained previously for several cyclic ethers and predictions of standard molar volumes based on group contribution approach were tested and analysed

  16. Densities, Excess Molar Volumes, Viscosities, and Refractive Indices of Binary Mixtures of n-Butyl Acetate with 1-Chloroalkanes (C4-C8) at 298.15 K

    Science.gov (United States)

    Iloukhani, H.; Khanlarzadeh, K.; Rakhshi, M.

    2011-03-01

    Densities, viscosities, and refractive indices of binary mixtures of n-butyl acetate (1) +1-chlorobutane (2), +1-chloropentane (2), +1-chlorohexane (2), +1-chloroheptane (2), and +1-chlorooctane (2) were measured at 298.15 K for the liquid region and at ambient pressure for the whole composition range. The excess molar volumes V E were calculated from experimental densities. McAllister's three-body interaction, and Hind and Grunberg-Nissan models are used for correlating the viscosity of binary mixtures. The experimental data of binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.

  17. Densities, excess molar volumes, speeds of sound and isothermal compressibilities for {l_brace}2-(2-hexyloxyethoxy)ethanol + n-alkanol{r_brace} systems at temperatures between (288.15 and 308.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Amalendu [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India)], E-mail: palchem@sify.com; Gaba, Rekha [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India)

    2008-05-15

    The densities, {rho} and the speeds of sound, u, for {l_brace}2-(2-hexyloxyethoxy)ethanol (C{sub 6}E{sub 2}) + methanol, +1-propanol, +1-pentanol, and +1-heptanol{r_brace} have been measured as a function of composition using an Anton-Paar DSA 5000 densimeter at temperatures (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure over the whole concentration range. The {rho} and u values were used to calculate excess molar volumes, V{sup E}, and excess molar isentropic compressibility, K{sub S,m}{sup E}, respectively. Also, thermal expansivity, {alpha}, partial molar volume, V-bar{sub i}, and partial molar volume of the components at infinite dilution, V-bar{sub i}{sup 0}, have been calculated. The variation of these properties with composition and temperature of the mixtures are discussed in terms of molecular interactions.

  18. Buoyancy Effect of Ionic Vacancy on the Change of the Partial Molar Volume in Ferricyanide-Ferrocyanide Redox Reaction under a Vertical Gravity Field

    Directory of Open Access Journals (Sweden)

    Yoshinobu Oshikiri

    2013-01-01

    Full Text Available With a gravity electrode (GE in a vertical gravity field, the buoyancy effect of ionic vacancy on the change of the partial molar volume in the redox reaction between ferricyanide (FERRI and ferrocyanide (FERRO ions was examined. The buoyancy force of ionic vacancy takes a positive or negative value, depending on whether the rate-determining step is the production or extinction of the vacancy. Though the upward convection over an upward electrode in the FERRO ion oxidation suggests the contribution of the positive buoyancy force arising from the vacancy production, the partial molar volume of the vacancy was not measured. On the other hand, for the downward convection under a downward electrode in the FERRI ion reduction, it was not completely but partly measured by the contribution of the negative buoyancy force from the vacancy extinction. Since the lifetime of the vacancy is decreased by the collision between ionic vacancies during the convection, the former result was ascribed to the shortened lifetime due to the increasing collision efficiency in the enhanced upward convection over an upward electrode, whereas the latter was thought to arise from the elongated lifetime due to the decreasing collision efficiency by the stagnation under the downward electrode.

  19. Excess molar volume along with viscosity, refractive index and relative permittivity for binary mixtures of exo-tetrahydrodicyclopentadiene with four octane isomers

    International Nuclear Information System (INIS)

    Highlights: • Binary mixtures of JP-10 with octane isomers are studied as model hydrocarbon fuels. • Density, viscosity, refractive index and relative permittivity are determined. • Excess molar volumes and viscosity deviations are calculated and correlated. - Abstract: The fundamental physical properties including density, viscosity, refractive index and relative permittivity, have been measured for binary mixtures of exo-tetrahydrodicyclopentadiene (JP-10) with four octane isomers (n-octane, 3-methylheptane, 2,4-dimethylhexane and 2,2,4-trimethylpentane) over the whole composition range at temperatures T = (293.15 to 313.15) K and pressure p = 0.1 MPa. The values of excess molar volume (VmE), viscosity deviation (Δη), refractive index deviation (ΔnD) and relative permittivity deviation (Δεr) are then calculated. All of the values of VmE and Δη are observed to be negative, while those of ΔnD and Δεr are close to zero. The effects of temperature and composition on the variation of VmE values are discussed. The negative values of VmE and Δη are conductive to high-density and low-resistance of fuels, which is favorable for the design and preparation of advanced hydrocarbon fuels

  20. Hyperpolarized 3He apparent diffusion coefficient MRI of the lung: reproducibility and volume dependency in healthy volunteers and patients with emphysema

    DEFF Research Database (Denmark)

    Diaz, S.; Casselbrant, I.; Piitulainen, E.;

    2008-01-01

    PURPOSE: To measure the apparent diffusion coefficient (ADC) of hyperpolarized (HP) (3)He gas using diffusion weighted MRI in healthy volunteers and patients with emphysema and examine the reproducibility and volume dependency. MATERIALS AND METHODS: A total of eight healthy volunteers and 16...... in mean ADC with increased inhaled gas volume was observed in both groups. CONCLUSION: Mean ADC and SD of HP (3)He MRI is reproducible and discriminates well between healthy controls and patients with emphysema at the higher gas volume. This method is robust and may be useful to gain new insights...

  1. Improved method to determine the molar volume and compositions of the NaCl-H2O-CO2 system inclusion

    Institute of Scientific and Technical Information of China (English)

    SONG YuCai; HU WenXuan; NI Pei; DUAN ZhenHao; ZHANG XueFeng

    2007-01-01

    On the basis of Parry's method (1986),an improved method was established to determine the molar volume(Vm)and compositions(X)of the NaCl-H2O-CO2(NHC)system inclusion.To use this method,the determination of Vm-X only requires three microthermometric data of a NHC inclusion:partial homogenization temperature(Th,CO2),salinity(s)and total homogenization temperature(Th).Theoretically,four associated equations are needed containing four unknown parameters:Xco2,XNcl,Vm and F (volume fraction of CO2 phase in total inclusion when occurring partial homogenization).When they are released,the Vm-X are determined.The former three equations,only correlated with Th,co2,S and F,have simplified expressions:XCO2=f1(Th,CO2,S,F),XNaCl=f2(Th,CO2,S,F),Vm=f3(Th,CO2,S,F).The last one is the thermodynamic relationship of Xco2,Xnacl,vm and Th:f4(XCO2,XNacl,Vm,Th)=0. Since the above four associated equations are complicated,it is necessary to adopt iterative technique to release them.The technique can be described by:(i)Freely input a F value(0≤F≤1),with Th,co2 and S,into the former three equations.As a result,Xco2,XNacl and the molar volume value recorded as Vm1 are derived.(ii)Input the Xco2 and XNacl gotten in the step above into the last equation,and another molar volume value recorded as Vm2 is determined.(iii) If Vm1 is unequal to Vm2,the calculation will be restarted from"(i)".The iteration is completed until Vm1 is equal to Vm2,which means that the four associated equations are released.Compared to Parry's (1986) solution method,the improved method is more convenient to use,as well as more accurate to determine Xco2.It is available for a NHC inlusion whose partial homogenization temperature is higher than clatherate melting temperature and there are no solid salt crystals in the inclusion at parital homogenization.

  2. Improved method to determine the molar volume and compositions of the NaCl-H2O-CO2 system inclusion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of Parry’s method (1986), an improved method was established to determine the molar volume (Vm) and compositions (X) of the NaCl-H2O-CO2 (NHC) system inclusion. To use this method, the determination of Vm-X only requires three microthermometric data of a NHC inclusion: partial homog-enization temperature (Th ,CO2), salinity (S) and total homogenization temperature (Th). Theoretically, four associated equations are needed containing four unknown parameters: X CO2, XNaCl, Vm and F (volume fraction of CO2 phase in total inclusion when occurring partial homogenization). When they are released, the Vm-X are determined. The former three equations, only correlated with Th ,CO2, S and F, have simplified expressions:XCO2=f1(Th,CO2,S,F),XNaCl=f2(Th,CO2,S,F),Vm=f3(Th,CO2,S,F). The last one is the thermodynamic relationship of X CO2, XNaCl, Vm and Th:f4(XCO2,XNaCl,Vm,Th)=0.Since the above four associated equations are complicated, it is necessary to adopt iterative technique to release them. The technique can be described by:(i) Freely input a F value (0≤F≤1),with Th ,CO2 and S, into the former three equations. As a result,X CO 2,XNaCl and the molar volume value recorded as Vm1 are derived. (ii) Input the X CO2 and XNaCl gotten in the step above into the last equation, and another molar volume value recorded as Vm2 is determined. (iii) If Vm1 is unequal to Vm2, the calculation will be restarted from “(i)”. The iteration is completed until Vm1 is equal to Vm2, which means that the four associated equations are released. Compared to Parry’s (1986) solution method, the improved method is more convenient to use, as well as more accurate to determine X CO 2. It is available for a NHC inlusion whose partial homogenization temperature is higher than clatherate melting temperature and there are no solid salt crystals in the inclusion at parital homogenization.

  3. Excess molar volumes and viscosities of binary mixtures of some polyethers with 1-propanol at 288.15, 298.15, and 308.15 K

    Indian Academy of Sciences (India)

    Amalendu Pal; Anil Kumar

    2004-01-01

    Excess molar volumes ($V_{m}^{E}$) and viscosities () have been measured as a function of composition for binary liquid mixtures of 1-propanol, C3H7OH, with diethylene glycol diethyl ether (bis(2-ethoxyethyl)ether), C2H5(OC2H4)2OC2H5, and diethylene glycol dibutyl ether (bis(2-butoxyethyl)ether), C4H9(OC2H4)2OC4H9, at 288.15, 298.15, and 308.15 K and at atmospheric pressure. The excess volume results included the following mixing quantities at all range of concentrations and at equimolar concentrations: , volume expansivity; ( $V^{E}_{m}$/ ), and ( /) at 298.15 K. The obtained results were then compared with the calculated values by using the Flory theory of liquid mixtures. The theory predicts the values rather well, while the calculated values of ( $V^{E}_{m}$/ ) and ( /) show variation with alkyl chain length of the polyether. The results are discussed in terms of order or disorder creation. From the viscosity data, deviations in viscosity ( ) have been calculated. These values are negative over the entire range of composition. The results for $V^{E}_{m}$, and are discussed in terms of interaction between components.

  4. Excess Molar Volume,Viscosity and Heat Capacity for the Mixture of 1,2—Propanediol—Water at Different Temperatures

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 唐多强; 靳凤民

    2003-01-01

    Experimental densities,viscosities and heat capacities at different emperatures were presented over the entire mole fraction range for the binary mixture of 1,2-propanediol and water,Density values were used in the determination of excess molar volumes,VE,At the same time,the excess viscosity was in vestigated,The values of VE and ηE were fitted to the Redlich-kister equation.Good agreement was observed,The excess volumes are negative over the entire range of composition.They show an U-shaped-concentration dependence and decrease in abolute values with increase of temperature,Values of ηE are negative over the entire range of the composition,and has a trend very similar to that of VE ,The analysis shows that at any temperature the specific heat of mixture is a linear function of the composition as x1>20%,All the extended lines intersect at one point.An empirical equation is obtained to calculate the specific heat to mixture at any composition and temperature in the experimental range.

  5. Partial molar volumes of organic solutes in water. XX. Glycine(aq) and L-alanine(aq) at temperatures (298 to 443) K and at pressures up to 30 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Cibulka, Ivan, E-mail: ivan.cibulka@vscht.c [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Hnedkovsky, Lubomir [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague (Czech Republic); Sedlbauer, Josef [Department of Chemistry, Technical University of Liberec, Studentska 2, 461 17 Liberec (Czech Republic)

    2010-02-15

    Density data for dilute aqueous solutions of two amino acids (glycine, L-alanine) obtained using a flow vibrating-tube densimeter are presented together with partial molar volumes at infinite dilution (standard molar volumes, V{sub m,2}{sup 0}) calculated from the measured data. The experiments were performed at temperatures from (298 up to 443) K at pressures close to the saturation line of water, at pressures in the range from (15 to 17) MPa, and at 30 MPa. Values of an analogue of isothermal compressibility, kappa{sub T,2}{sup 0}=-(1/V{sub m,2}{sup 0})(partial derivV{sub m,2}{sup 0}/partial derivp){sub T}, are also evaluated. Maxima on the curves V{sub m,2}{sup 0}(T) and kappa{sub T,2}{sup 0}(T) are observed and discussed. The new data along with literature values of standard molar volumes and heat capacities are used for generating the recommended parameterization of an equation of state for standard molar thermodynamic properties of the aqueous amino acids.

  6. The study of partial and excess molar volumes for binary mixtures of nitrobenzene and benzaldehyde with xylene isomers from T = (298.15 to 318.15 K and P = 0.087 MPa

    Directory of Open Access Journals (Sweden)

    Hamid R. Rafiee

    2016-09-01

    Full Text Available Based on density measurements, partial and excess molar volumes for binary mixtures of nitrobenzene and benzaldehyde with three isomers of xylene have been measured. The whole range of composition and temperatures from T = (298.15 to 318.15 K at ambient pressure 0.087 MPa, has been considered. The excess molar volumes were negative and decreased by increasing temperature for all mixtures which are explained based on intermolecular interactions. Excess molar volumes for solutions including nitrobenzene were absolutely larger than benzaldehyde binary mixtures. The partial and excess molar volumes for each component have been appraised and reported. The excess molar volumes have been successfully fitted to Redlich–Kister equation.

  7. Excess molar volumes and deviation in viscosities of binary liquid mixtures of acrylic esters with hexane-1-ol at 303.15 and 313.15 K

    Directory of Open Access Journals (Sweden)

    Sujata S. Patil

    2014-12-01

    Full Text Available Densities and viscosities for the four binary liquid mixtures of methyl acrylate, ethyl acrylate, butyl acrylate and methyl methacrylate with hexane-1-ol at temperatures 303.15 and 313.15 K and at atmospheric pressure were measured over the entire composition range. These values were used to calculate excess molar volumes and deviation in viscosities which were fitted to Redlich–Kister polynomial equation. Recently proposed Jouyban Acree model was also used to correlate the experimental values of density and viscosity. The mixture viscosities were correlated by several semi-empirical approaches like Hind, Choudhary–Katti, Grunberg–Nissan, Tamura and Kurata, McAllister three and four body model equations. A graphical representation of excess molar volumes and deviation in isentropic compressibility shows positive nature whereas deviation in viscosity shows negative nature at both temperatures for all four binary liquid mixtures. Positive values of excess molar volumes show that volume expansion is taking place causing rupture of H-bonds in self associated alcohols. The results were discussed in terms of molecular interactions prevailing in the mixtures.

  8. Density, viscosity and excess molar volume of binary mixtures of tri-n-octylamine + diluents (n-heptane, n-octane, n-nonane, and n-decane) at various temperatures

    International Nuclear Information System (INIS)

    Highlights: • Densities and viscosities of tri-n-octylamine + n-heptane, +n-octane, +n-nonane, or +n-decane are determined. • The excess molar volume is calculated. • The Grunberg and Nissan equation and Fang and He equation are used to correlate the binary viscosities. -- Abstract: Densities (ρ) and viscosities (η) for binary mixtures of tri-n-octylamine (TOA) + n-heptane, TOA + n-octane, TOA + n-nonane, and TOA + n-decane are determined at T (283.15, 293.15, and 303.15) K and atmospheric pressure. The excess molar volume is calculated from the density data and is correlated by a Redlich–Kister type equation. The excess molar volume is negative for all the four systems. The results show that the volume accommodation effect is predominant in these systems. The Grunberg and Nissan equation and Fang and He equation for binary mixtures are used to correlate the experimental viscosity data. The Fang and He equation gives an average absolute deviation (AAD%) of 0.8% for TOA with alkane mixtures, better than that of 3.8% given by the Grunberg and Nissan equation

  9. Deciduous molar hypomineralization and molar incisor hypomineralization

    NARCIS (Netherlands)

    M.E.C. Elfrink; J.M. ten Cate; V.W.V. Jaddoe; A. Hofman; H.A. Moll; J.S.J. Veerkamp

    2012-01-01

    This study was embedded in the Generation R Study, a population-based prospective cohort study from fetal life until young adulthood. This study focused on the relationship between Deciduous Molar Hypomineralization (DMH) and Molar Incisor Hypomineralization (MIH). First permanent molars develop dur

  10. Ultrasonic velocities, densities, and excess molar volumes of binary mixtures of N,N-dimethyl formamide with methyl acrylate, or ethyl acrylate, or butyl acrylate, or 2-ethyl hexyl acrylate at T = 308.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Kondaiah, M. [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, Andhra Pradesh (India); Sravana Kumar, D. [Dr. V.S. Krishna Govt. Degree College, Visakhapatnam, Andhra Pradesh (India); Sreekanth, K. [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, Andhra Pradesh (India); Krishna Rao, D., E-mail: krdhanekula@yahoo.co.in [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, Andhra Pradesh (India)

    2011-12-15

    Highlights: > Positive values of V{sub m}{sup E}, indicate dispersion forces between acrylic esters and DMF. > V{sub m}{sup E} values compared with Redlich-Kister polynomial. > Partial molar volumes data conclude that weak interactions exist in the systems. > Measured velocity values compared with theoretical values obtained by polynomials. - Abstract: Ultrasonic velocities, u, densities, {rho}, of binary mixtures of N,N-dimethyl formamide (DMF) with methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), and 2-ethyl hexyl acrylate (EHA), including pure liquids, over the entire composition range have been measured at T = 308.15 K. Using the experimental results, the excess molar volume, V{sub m}{sup E}, partial molar volumes, V-bar {sub m,1}, V-bar{sub m,2}, and excess partial molar volumes, V-bar{sub m,1}{sup E}, V-bar{sub m,2}{sup E} have been calculated. Molecular interactions in the systems have been studied in the light of variation of excess values of calculated properties. The excess properties have been fitted to Redlich-Kister type polynomial and the corresponding standard deviations have been calculated. The positive values of V{sub m}{sup E} indicate the presence of dispersion forces between the DMF and acrylic ester molecules. Further theoretical values of sound velocity in the mixtures have been evaluated using various theories and have been compared with experimental sound velocities to verify the applicability of such theories to the systems studied. Theoretical ultrasonic velocity data have been used to study molecular interactions in the binary systems investigated.

  11. Excess molar volumes and deviation in viscosities of binary liquid mixtures of acrylic esters with hexane-1-ol at 303.15 and 313.15 K

    OpenAIRE

    Sujata S. Patil; Sunil R. Mirgane; Balasaheb R. Arbad

    2014-01-01

    Densities and viscosities for the four binary liquid mixtures of methyl acrylate, ethyl acrylate, butyl acrylate and methyl methacrylate with hexane-1-ol at temperatures 303.15 and 313.15 K and at atmospheric pressure were measured over the entire composition range. These values were used to calculate excess molar volumes and deviation in viscosities which were fitted to Redlich–Kister polynomial equation. Recently proposed Jouyban Acree model was also used to correlate the experimental value...

  12. Assessment of treatment response by total tumor volume and global apparent diffusion coefficient using diffusion-weighted MRI in patients with metastatic bone disease: a feasibility study.

    Directory of Open Access Journals (Sweden)

    Matthew D Blackledge

    Full Text Available We describe our semi-automatic segmentation of whole-body diffusion-weighted MRI (WBDWI using a Markov random field (MRF model to derive tumor total diffusion volume (tDV and associated global apparent diffusion coefficient (gADC; and demonstrate the feasibility of using these indices for assessing tumor burden and response to treatment in patients with bone metastases. WBDWI was performed on eleven patients diagnosed with bone metastases from breast and prostate cancers before and after anti-cancer therapies. Semi-automatic segmentation incorporating a MRF model was performed in all patients below the C4 vertebra by an experienced radiologist with over eight years of clinical experience in body DWI. Changes in tDV and gADC distributions were compared with overall response determined by all imaging, tumor markers and clinical findings at serial follow up. The segmentation technique was possible in all patients although erroneous volumes of interest were generated in one patient because of poor fat suppression in the pelvis, requiring manual correction. Responding patients showed a larger increase in gADC (median change = +0.18, range = -0.07 to +0.78 × 10(-3 mm2/s after treatment compared to non-responding patients (median change = -0.02, range = -0.10 to +0.05 × 10(-3 mm2/s, p = 0.05, Mann-Whitney test, whereas non-responding patients showed a significantly larger increase in tDV (median change = +26%, range = +3 to +284% compared to responding patients (median change = -50%, range = -85 to +27%, p = 0.02, Mann-Whitney test. Semi-automatic segmentation of WBDWI is feasible for metastatic bone disease in this pilot cohort of 11 patients, and could be used to quantify tumor total diffusion volume and median global ADC for assessing response to treatment.

  13. Densities, excess molar volume, isothermal compressibility, and isobaric expansivity of (dimethyl carbonate + n-hexane) systems at temperatures (293.15 to 313.15) K and pressures from 0.1 MPa up to 40 MPa

    International Nuclear Information System (INIS)

    The densities of dimethyl carbonate, n-hexane and their mixtures were measured for 12 compositions at five different temperatures varying from (293.15 to 313.15) K and over the pressure range of (0.1 to 40) MPa. The densities of pure substances and their mixtures at atmospheric pressure were measured by a vibrating-tube densimeter. The densities at high pressures were measured by a variable-volume autoclave and precise analytical balance. The excess molar volume, isothermal compressibility, and isobaric expansivity were derived from the experimental densities.

  14. Study on the Change of Refractive Index on Mixing, Excess Molar Volume and Viscosity Deviation for Aqueous Solution of Methanol, Ethanol, Ethylene Glycol, 1-Propanol and 1, 2, 3-Propantriol at T = 292.15 K and Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Fardad Koohyar

    2012-08-01

    Full Text Available For aqueous solutions of methanol, ethanol, ethylene glycol, 1-propanol and 1, 2, 3-propantriol the change of refractive indices on mixing, excess molar volumes and viscosity deviations were calculated from the experimental data at 292.15 K. These experimental data (refractive indices, densities and viscosities were measured over the whole mole fractions range in atmospheric pressure and at T = 292.15 K. For these mixtures, excess thermodynamic properties have been correlated with the Redlich-Kister polynomial equation (and experimental equation to derive the coefficients and standard errors.

  15. Excess Molar Volumes and Viscosities for the Binary Mixtures of n-Octane, n-Decane, n-Dodecane, and n-Tetradecane with Octan-2-ol at 298.15 K

    OpenAIRE

    Mahajan, Arvind R.; Sunil R. Mirgane

    2013-01-01

    Experimental values of densities (ρ) and viscosities (η) in the binary mixtures of n-octane, n-decane, n-dodecane, and n-tetradecane with octan-2-ol are presented over the whole range of mixture composition at T=298.15 K. From these data, excess molar volume (VmE), deviations in viscosity (Δη), and excess Gibbs free energy of activation ΔG∗E have been calculated. These results were fitted to Redlich-Kister polynomial equations to estimate the binary coefficients and standard errors. Jouyban-...

  16. Studies of viscous antagonism, excess molar volumes, viscosity deviation and isentropic compressibility of ternary mixtures containing N,N-dimethylformamide, benzene and some ethers at 298.15 K

    Directory of Open Access Journals (Sweden)

    RIJU CHANDA

    2010-12-01

    Full Text Available The densities (r and viscosities (h for ternary liquid mixtures of N,N-dimethylformamide + benzene + an ether were measured as a function of composition at 298.15 K. From experimental measurements, the excess molar volumes (VE, viscosity deviation (Δh, antagonic interaction index (IA and Gibbs free energy of activation for viscous flow (ΔGE were evaluated. The speeds of sound were also measured and excess isentropic compressibilities (KsE were calculated at the experimental temperature. The results are discussed and interpreted in terms of molecular package and specific interaction predominated by hydrogen bonding.

  17. Excess Molar Volume, Viscosity and Heat Capacity for the Binary Mixture of p-Xylene and Acetic Acid at Different Temperatures%对二甲苯和醋酸二元液体混合物在不同温度下的超额摩尔体积、粘度和热容

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 唐多强; 尹秋响; 赵长伟

    2002-01-01

    Experimental densities, viscosities and heat capacities at different temperatures were presented overthe entire range of mole fraction for the binary mixture of p-xylene and acetic acid. Density values were used in thedetermination of excess molar volumes, VE. At the same time, the excess viscosity and excess molar heat capacitieswere calculated. The values of VE, ηE and cpE were fitted to the Redlich-Kister equation. Good agreements wereobserved. The excess molar volumes are positive with a large maximum value located in the central concentrationrange. The excess viscosity has an opposite trend to the excess molar volume VE. ηE values are negative over theentire range of the mixture. The cure of dependence of cEp on concentration has a special shape. The molecularinteraction between p-xylene and acetic acid is discussed.

  18. Effects of concentration and temperature on molar volumes of L-serine, L-isoleucine, and L-glutamine in aqueous NaCl and NaNO3 solutions

    Science.gov (United States)

    Riyazuddeen; Kumar, Dheeraj; Afrin, Sadaf

    2014-01-01

    Densities of L-serine, L-isoleucine, L-glutamine in 1.5 mol kg-1 aqueous NaCl, and NaNO3 solutions have been measured for several molal concentrations of amino acids at temperatures from 298.15 to 323.15 K. The partial molar volumes (ϕ{/v 0}) of L-serine, L-isoleucine, and L-glutamine in 1.5 mol kg-1 aqueous NaCl/NaNO3 solutions have been computed using density data. The transfer partial molar volumes (Δtrϕ{/v 0}) of L-serine, L-isoleucine, and L-glutamine from water to 1.5 mol kg-1 aqueous NaCl/1.5 mol kg-1 aqueous NaNO3 solutions have been determined at 298.15 K. The trends of variation of ϕ{/v 0} and Δtrϕ{/v 0} with change in temperature have been discussed in terms of ion-ion, ion-hydrophilic, and ion-hydrophobic interactions operative in solutions.

  19. Volume of the effect compartment in simulations of neuromuscular block

    NARCIS (Netherlands)

    Nigrovic, Vladimir; Proost, Johannes H.; Amann, Anton; Bhatt, Shashi B.

    2005-01-01

    Background: The study examines the role of the volume of the effect compartment in simulations of neuromuscular block (NMB) produced by nondepolarizing muscle relaxants. Methods: The molar amount of the postsynaptic receptors at the motor end plates in muscle was assumed constant; the apparent recep

  20. Compressed liquid densities and excess molar volumes for (CO{sub 2} + 1-pentanol) binary system at temperatures from 313 to 363 K and pressures up to 25 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Zuniga-Moreno, Abel [Instituto Politecnico Nacional, ESIQIE, Laboratorio de Termodinamica, Edif. Z, Secc. 6, 1er piso, UPALM Zacatenco, 07738, Lindavista, Mexico, D.F. (Mexico); Galicia-Luna, Luis A. [Instituto Politecnico Nacional, ESIQIE, Laboratorio de Termodinamica, Edif. Z, Secc. 6, 1er piso, UPALM Zacatenco, 07738, Lindavista, Mexico, D.F. (Mexico)], E-mail: lgalicial@ipn.mx; Sandler, Stanley I. [Department of Chemical Engineering, University of Delaware, Newark, DE 19716-3119 (United States)

    2008-02-15

    Measurements of compressed liquid densities for 1-pentanol and for {l_brace}CO{sub 2} (1) + 1-pentanol (2){r_brace} system were carried out at temperatures from 313 K to 363 K and pressures up to 25 MPa. Densities were measured for binary mixtures at 10 different compositions, x{sub 1} = 0.0816, 0.1347, 0.3624, 0.4651, 0.6054, 0.7274, 0.8067, 0.8573, 0.9216, and 0.9757. A vibrating tube densimeter was used to perform density measurements using two reference calibration fluids. The uncertainty is estimated to be better than {+-}0.2 kg . m{sup -3} for the experimental density measurements. For each mixture and for 1-pentanol, the experimental densities were correlated using an explicit volume equation of six parameters and an 11-parameter equation of state (EoS). Excess molar volumes were determined for the (CO{sub 2} + 1-pentanol) system using 1-pentanol densities calculated from the 11-parameter EoS and CO{sub 2} densities calculated from a multiparameter reference EoS.

  1. Third molar infections.

    Science.gov (United States)

    Gutiérrez-Pérez, José Luis

    2004-01-01

    Pericoronitis is an infectious disease often associated with the eruption of a third molar. It can be either acute (serous and suppurative) or chronic. Pain is usually the predominant symptom in acute stages, whereas chronic forms of the disease may display very few symptoms. Both present exudate. The infection is multimicrobial, predominantly caused strictly by betalactamase-producing anaerobeic microorganisms. Treatment measures are symptomatic, antimicrobial and surgical. Antimicrobial treatment is indicated for preoperative prophylaxis when there is a high risk of postoperative infection and, during the acute stages of suppurative pericoronitis when surgery must be postponed. First-line treatment in this case consists of amoxicillin with associated clavulanic acid. Although surgical treatment of pericoronitis presenting at the third molar is indicated as a Grade C recommendation for extraction, it is the most common indication for extraction of a retained third molar, owing to the improved quality of life it can offer the patient.

  2. Excess Molar Volumes and Viscosities for the Binary Mixtures of n-Octane, n-Decane, n-Dodecane, and n-Tetradecane with Octan-2-ol at 298.15 K

    Directory of Open Access Journals (Sweden)

    Arvind R. Mahajan

    2013-01-01

    Full Text Available Experimental values of densities (ρ and viscosities (η in the binary mixtures of n-octane, n-decane, n-dodecane, and n-tetradecane with octan-2-ol are presented over the whole range of mixture composition at T=298.15 K. From these data, excess molar volume (VmE, deviations in viscosity (Δη, and excess Gibbs free energy of activation ΔG∗E have been calculated. These results were fitted to Redlich-Kister polynomial equations to estimate the binary coefficients and standard errors. Jouyban-Acree model is used to correlate the experimental values of density and viscosity at T=298.15 K. The values of VmE have been analyzed using Prigogine-Flory-Patterson (PFP theory. The results of the viscosity composition are discussed in the light of various viscosity equations suggested by Grunberg-Nissan, Tamara and Kurata, Hind et al., Katti and Chaudhri, Heric, Heric and Brewer, and McAllister multibody model. The values of Δlnη have also been analyzed using Bloomfield and Dewan model. The experiments on the constituted binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.

  3. Endodontic treatment of molars

    Directory of Open Access Journals (Sweden)

    Stürzlinger, Heidi

    2006-02-01

    Full Text Available Objective: Commissioned by the German Institute of Medical Documentation and Information (DIMDI the Austrian Health Institute (ÖBIG prepared a HTA report on the long-term effectiveness of endodontic treatment (root canal treatment, RCT of molars. The focus is to examine factors influencing the outcome of endodontic treatment and showing their impact on long-term results. Additionally, economic aspects of root canal treatment in Germany are discussed. Methodology: By performing a systematic literature search in 29 databases (e.g. MEDLINE, the Cochrane Library and by hand searching two peer-reviewed endodontic journals the authors could identify 750 relevant articles, of which finally 18 qualified for assessment. Results: The findings show that the most relevant factor influencing the long-term outcome of endodontic treatment is the preoperative status of a tooth. The lowest success rates are reported for molars with a preoperative devital or necrotic pulp and persisting periapical lesions (so called periapical disease. Discussion: Even if there is no positive selection of patients and the RCT is performed by a normal dentist rather than an endodontist - a fact which is very common - long-term success rates of more then 90% are possible. The overall success rates for endodontic treatment of molars therefore seem to be similar to those of other tooth-types. Conclusions: Especially primary, conventional (i.e. non-surgical root canal treatment is an effective and efficient therapy for endodontically ill molars, especially if no large periapical lesion persists. Nonetheless, a long term successful endodontic therapy requires a thorough assessment of the pre-operative status of the molar and treatment according to established guidelines.

  4. 二氧化碳与2-丁醇二元体系在高压下的亨利系数和偏摩尔体积性质计算%Calculation of Henry's coefficient and partial molar volume of carbon dioxide in 2-butanol at elevated pressures

    Institute of Scientific and Technical Information of China (English)

    田爱琴; 孙洪博; 陈文涛; 王琳

    2012-01-01

    Based on vapor-liquid phase equilibria data for CO2+2-butanol binary system from 323K to 353K by constant-volume visual high-pressure cell, the solubility model of CO2 in 2-butanol was established with Krichevsky-Kasarnovsky equation. Henry's coefficients and partial molar volumes of CO2 at infinite dilution were calculated. Meanwhile, Partial molar volumes of CO2 and 2-butanol at equilibrium were calculated from partial molar volumes properties together with Peng-Robinson equation of state and Van der Waals-2 mixed rule. The results showed that Henry's coefficients and partial molar volumes of CO2 at infinite dilution were both the function of temperature, and Henry's coefficients decreased with temperature. The partial molar volumes of CO2 at infinite dilution were negative and the magnitudes decreased with temperature. The calculated effects of partial molar volumes of vapor and liquid phase at equilibrium showed that the partial molar volumes of CO2 and 2-butanol in liquid phase were positive, but in vapor the partial molar volumes of CO2 were negative and the partial molar volumes of 2-butanol were positive. The research provided theoretical basis for deciding supercritical extraction conditions and instructing industrial production.%利用固定体积可视高压釜测量出的在323 K~353 K温度范围内的CO2与2-丁醇二元体系在高压下的汽液相平衡数据,根据Krichevsky-Kasarnovsky方程建立了CO2在液相中的溶解度模型,得到了该二元体系在高压下的亨利系数和CO2在无限稀释溶液中的偏摩尔体积等性质.同时根据偏摩尔体积性质和Peng-Robinson状态方程及Van der Waals-2混合规则来计算该体系在平衡状态下的气、液相的偏摩尔体积.结果表明CO2在2-丁醇中的亨利系数和CO2在无限稀释溶液中的偏摩尔体积均为温度的函数,CO2在2-丁醇中的亨利系数随温度的升高而降低.CO2在无限稀释溶液中的偏摩尔体积(V)1∞在研究温度下均为

  5. Endodontic treatment of molars

    OpenAIRE

    Stürzlinger, Heidi; Bodenwinkler, Andrea; Habl, Claudia

    2006-01-01

    Objective: Commissioned by the German Institute of Medical Documentation and Information (DIMDI) the Austrian Health Institute (ÖBIG) prepared a HTA report on the long-term effectiveness of endodontic treatment (root canal treatment, RCT) of molars. The focus is to examine factors influencing the outcome of endodontic treatment and showing their impact on long-term results. Additionally, economic aspects of root canal treatment in Germany are discussed. Methodology: By performing a systematic...

  6. Determination of Enthalpy Change of Reaction of Formation,Molar Heat Capacity and Constant-Volume Combustion Energy of the Ternary Solid Complex Lu(Et2dtc)3(phen)%Lu(Et2dtc)3(phen)的生成反应焓变、摩尔热容和恒容燃烧能测定

    Institute of Scientific and Technical Information of China (English)

    葛红光; 陈三平; 谢钢; 扬旭武; 高胜利; 史启祯

    2006-01-01

    A ternary solid complex Lu(Et2dtc)3(phen) has been obtained from the reaction of hydrated lutetiumchloride with sodium diethyldithiocarbamate (NaEt2dtc), and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol. IR spectrum of the complex indicates that Lu3+ binds with sulfur atom in the Na (Et2dtc)3 and nitrogen atom in the o-phen. The enthalpy change of liquid-phase reaction of formation of the complex, △rHm(-)(1), was determined to be (-32.821 ± 0.147 ) Kj·mol-1 at 298.15 K by an RD-496 Ⅲ type heat conduction microcalormeter. The enthalpy change of the solid-phase reaction of formation of the complex, △rHm(-) (s), was calculated to be (104.160 ± 0.168) Kj · mol-1 on the basis of an appropriate thermochemistry cycle. The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, such as the activation enthalpy (△H(-)≠), the activation entropy (△S(-)≠), the activation free energy (△G≠(-)), the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A) and the reaction order (n), were obtained by combination the reaction thermodynamic and kinetic equations with the data of thermokinetic experiments. The molar heat capacity of the complex, cm, was determined to be (82.23 ± 1.47) J·mol-1·K-1 by the same microcalormeter. The constant-volume combustion energy of the complex, △Cu, was determined as (-17 898.228 ± 8.59) Kj·mol-1 by an RBC-Ⅱ type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, △cHm(-), and standard enthalpy of formation, △fHm(-), were calculated to be (-17 917.43 ± 8.11) Kj·mol-1 and (-859.95 ±10.12) Kj·mol-1, respectively.

  7. 对、邻二甲苯和醋酸二元液体混合物在不同温度和压力下的密度和超额摩尔体积%Density and Excess Molar Volume of Binary Mixtures of p-Xylene+Acetic Acid and o-Xylene+Acetic Acid at Different Temperatures and Pressures

    Institute of Scientific and Technical Information of China (English)

    杨天宇; 夏淑倩; 邸志国; 马沛生

    2008-01-01

    A new apparatus was designed with a thick-walled glass capillary, electric heater tube with red copper and heat preservation. The thick-walled glass capillary was used for its advantages of resistance to acid corrosion and pressure, and ease of observation. The experimental densities over the entire range of mole fraction for the bi- nary mixture of p-xylene+acetic acid and o-xylene+acetic acid were measured using the new apparatus at tempera- tures ranging from 313.15K to 473.15K and pressure ranging from 0.20 to 2.0 MPa. The density values were used in the determination of excess molar volumes, VE. The Redlich-Kister equation was used to fit the excess molar volume values, and the coefficients and estimate of the standard error values were presented. The experimental re- suits prove that the density measurement apparatus is successful.

  8. Relation of Plasma Lipoprotein(a) to Subclinical Coronary Plaque Volumes, Three-Vessel and Left Main Coronary Disease, and Severe Coronary Stenoses in Apparently Healthy African-Americans With a Family History of Early-Onset Coronary Artery Disease.

    Science.gov (United States)

    Kral, Brian G; Kalyani, Rita R; Yanek, Lisa R; Vaidya, Dhananjay; Fishman, Elliot K; Becker, Diane M; Becker, Lewis C

    2016-09-01

    Serum lipoprotein(a) [Lp(a)] is a coronary artery disease (CAD) risk factor in persons of European ancestry. Levels are twofold to threefold higher in African-Americans (AAs), but reported associations with CAD have been inconsistent. The relation of Lp(a) with the extent and severity of subclinical coronary plaque has not been described in AAs. We screened 269 apparently healthy AAs for risk factors and coronary plaque using advanced coronary computed tomographic angiography. Total coronary plaque (TCP), noncalcified coronary plaque, and calcified coronary plaque volumes (mm(3)) were quantified using a validated automated method. Lp(a) was measured by ELISA. Multivariable modeling was performed with adjustment for traditional CAD risk factors and intrafamilial correlations. Mean age was 51 ± 11 years and 64% were female. Plaque was present in 41%. Lp(a) was independently associated with TCP volume [log(TCP + 1)] (p = 0.04), 3-vessel and/or left main involvement (p = 0.04), and at least 1 stenosis >50% (p = 0.006). Best-fit regression analyses showed that subjects with Lp(a) >40 mg/dl were threefold more likely to have 3-vessel and/or left main disease (95% confidence interval 1.4 to 6.8, p = 0.005) and fourfold more likely to have stenosis >50% (95% confidence interval 1.3 to 15.0, p = 0.02). In subjects with plaque (n = 110), multivariable models showed the Lp(a) level was significantly and independently associated with TCP (p = 0.009), noncalcified coronary plaque (p = 0.01), and calcified coronary plaque (p = 0.003) and affected vessel length (p = 0.01). In conclusion, high Lp(a) is strongly associated with coronary plaque volumes, extent, and severity in apparently healthy AAs. High levels of Lp(a) may be particularly important in the pathogenesis of CAD in AAs. PMID:27530333

  9. Molar Incisor Hypomineralization.

    Science.gov (United States)

    Rao, Murali H; Aluru, Srikanth C; Jayam, Cheranjeevi; Bandlapalli, Anila; Patel, Nikunj

    2016-01-01

    Molar incisor hypomineralization (MIH) is a developmental defect affecting teeth. High prevalence rates of MIH and its clinical implications are significant for both the patients and clinicians. A wide variation in defect prevalence (2.4-40.2%) is reported. It seems to differ with regions and various birth cohorts. Some of the recent prevalence studies are tabulated. Patient implications include hypersensitive teeth, rapid progression of caries, mastication impairment due to rapid attrition, and esthetic repercussions. Implications for clinicians include complexity in treatment planning and treatment implementation, poor prognosis of the restorations, difficulty in achieving pain control during treatment, and behavior management problems. Intention of this paper is to review the etio-pathogenesis, prevalence, clinical features, diagnostic features, and eventually present a sequential treatment approach, i.e., in accordance with current clinical practice guidelines. PMID:27595731

  10. Excess Volumes, Densities, Speeds of Sound, and Viscosities for the Binary Systems of 1-Octanol with Hexadecane and Squalane at (298.15, 303.15 and 308.15) K

    Science.gov (United States)

    Dubey, Gyan P.; Sharma, Monika

    2008-08-01

    Excess molar volumes, {V_m^E } , excess molar isentropic compressibilities, {K_{S,m}^E } , and deviations of the speeds of sound, u D, from their ideal values u id in an ideal mixture for binary mixtures of 1-octanol, C8H17OH, with hexadecane, C16H34, and squalane (2,6,10,15,19,23-hexamethyltetracosane), C30H62, at T = (298.15, 303.15, and 308.15) K and at atmospheric pressure were derived from experimental density, ρ, and speed-of-sound data, u. Viscosity measurements were also carried out for the same mixtures. The Prigogine-Flory-Patterson (PFP) theory has been applied to analyze {V_m^E} of these systems. Furthermore, the apparent molar volumes, {overline{{V}}_{\\varphi ,i}^0 } and apparent molar compressibility, {overline{{K}}_{\\varphi ,i}^{ 0} } of the components at infinite dilution have been calculated.

  11. Remembering apparent behavior

    DEFF Research Database (Denmark)

    Wagoner, Brady

    2011-01-01

    The present experiment systematically investigates the role of narrative templates (Wertsch, 2002) in remembering. To stimulate the construction of a diversity of narratives I used Heider and Simmel’s (1944) celebrated “apparent behavior” film, in which geometric shapes moving around a screen are...

  12. Outcome of Subsequent Pregnancies in Familial Molar Pregnancy

    Directory of Open Access Journals (Sweden)

    Masoumeh Fallahian

    2013-01-01

    Full Text Available Familial recurrent molar pregnancy is an exceedingly rare condition, in which completehydatidiform moles are mostly diploid but biparental in origin and the outcome of subsequentpregnancies is likely to be a hydatidiform mole or other type of reproductiveloss. We previously reported a case of familial molar pregnancy (family K comprisingfive affected members (four sisters and one of their cousins each with at least one hydatidiformmole (HM. In addition to the molar pregnancies, these patients have a total ofthree miscarriages and 8 normal pregnancies leading to healthy children; but the youngestmember of this family has given birth to a boy with Down syndrome.Our second family (case S includes two sisters with diploid biparental complete moles.They have a total of six molar pregnancies with no living child. Recently the younger sisterhad a partial molar pregnancy with apparently normal XX fetus accompanying diffusemolar changes of the placenta that led to preeclampsia and preterm delivery.Overall, these families have had 26 pregnancies including 12 molar pregnancies (completeor partial and three abortions.We concluded that these families are predisposed to various genetic mutations, chromosomalabnormalities and clinical manifestations, which affect their offspring. Furtherstudies of patients are needed to determine any relationship between a history of familialmolar pregnancy and trisomy or other chromosomal abnormalities in offspring and geneticmutations in the products of conception to complete the puzzle and manage familialmolar pregnancy.

  13. Apparent Superluminal Behavior

    CERN Document Server

    Jackson, A D; Lautrup, B

    2000-01-01

    The apparent superluminal propagation of electromagnetic signals seen in recent experiments is shown to be the result of simple and robust properties of relativistic field equations. Although the wave front of a signal passing through a classically forbidden region can never move faster than light, an attenuated replica of the signal is reproduced ``instantaneously'' on the other side of the barrier. The reconstructed signal, causally connected to the forerunner rather than the bulk of the input signal, appears to move through the barrier faster than light.

  14. The apparent Universe

    Science.gov (United States)

    Binétruy, P.; Helou, A.

    2015-10-01

    We exploit the parallel between dynamical black holes and cosmological spacetimes to describe the evolution of Friedmann-Lemaître-Robertson-Walker universes from the point of view of an observer in terms of the dynamics of the apparent horizon. Using the Hayward-Kodama formalism of dynamical black holes, we clarify the role of the Clausius relation to derive the Friedmann equations for a Universe, in the spirit of Jacobson’s work on the thermodynamics of spacetime. We also show how dynamics at the horizon naturally leads to the quantum-mechanical process of Hawking radiation. We comment on the connection of this work with recent ideas to consider our observable Universe as a Bose-Einstein condensate and on the corresponding role of vacuum energy.

  15. Molarization of mandibular second premolar.

    Science.gov (United States)

    Mangla, Neha; Singh Khinda, Vineet Inder; Kallar, Shiminder; Singh Brar, Gurlal

    2014-05-01

    Macrodontia (megadontia, megalodontia, mac rodontism) is a rare shape anomaly that has been used to describe dental gigantism. Mandibular second premolars show an elevated variability of crown morphology, as are its eruptive potential and final position in the dental arch. To date, only eight cases of isolated macrodontia of second premolars have been reported in the literature. This case report presents clinical and radiographic findings of unusual and rare case of isolated unilateral molarization of left mandibular second premolar. How to cite this article: Mangla N, Khinda VIS, Kallar S, Brar GS. Molarization of Mandibular Second Premolar. Int J Clin Pediatr Dent 2014;7(2):137-139. PMID:25356014

  16. 1,2-丙二醇+丁醇/戊醇/己醇二元系的过量体积和黏度%Excess Molar Volumes and Viscosities of Binary Mixtures Composed of 1,2-Propanediol with Butanol, Pentanol or Hexanol

    Institute of Scientific and Technical Information of China (English)

    凌锦龙; 李灵; 杨佳琳

    2016-01-01

    常压下测定了1,2-丙二醇分别与丁醇、戊醇和己醇组成的二元系在293.15~318.15 K下的密度和黏度,建立了混合液密度和黏度随温度和组成变化的方程。计算了过量摩尔体积VE,黏度偏差∆η和过量流动活化自由能∆G*E。结果表明,三个二元系的过量摩尔体积在全浓度范围内均为正值,随温度升高,偏差增大,但发生最大偏差时的溶液组成不同;过量摩尔体积值按丁醇-戊醇-己醇顺序逐渐增大;黏度偏差和过量流动活化自由能三个体系显示了相同的变化关系,均为负值,且都随温度降低而偏差增大。利用Redlich-Kister方程对过量性质进行了关联。分析和讨论了分子间相互作用。%The densities and viscosities of binary mixtures consisting of butanol, pentanol or hexanol with 1,2-propanediol(12PD) were measured using pycnometer and Ubbelohde viscometer at 293.15~318.15 K under atmospheric pressure. The density and viscosity data of the binary mixtures were fitted as functions of composition and temperature. Excess molar volumes (VE), viscosity deviations (∆η) and excess Gibbs energy of activation of viscous flow (∆G*E) were calculated from the experimental data. The results show that the excess molar volumes are positive over the whole mole fraction range in the temperature range studied for all of the binary mixtures, and the deviation increases as temperature increases. However, the largest deviation varies in different solution compositions. The excess molar volume value increases following an order of butanol - pentanol – hexanol. Both∆η and∆G*E are negative over the whole mole fraction range in the temperature range studied for all of the binary mixtures, and the deviation increases as temperature decreases. All of the excess properties are correlated by the Redlich-Kister equation and the molecular interactions are analyzed.

  17. CANINE ECTOPIC TREATMENT WITH FIRST MOLAR EXTRACTION

    Directory of Open Access Journals (Sweden)

    Angelica Margo

    2015-06-01

    Full Text Available Decision to extract or not and the type of tooth must be analyzed carefully in orthodontic treatment. Preferable tooth to be extracted was the tooth with large caries or restoration. Usually the type of tooth to be extracted was second molar (if the third molar appears, incisor, first molar, and combination of several teeth. Orthodontic treatment with molar extraction is more difficult to treat and the result is usually compromise. There are several considerations in extracting first molar such as tooth with large caries or restoration, hypoplasia, periapical disease, large discrepancy, high maxilla-mandibular plane angle, and cases with anterior open bite. Nowadays, orthodontic cases with molar extraction do not prolong the treatment time compared to premolar extraction case, but the anchorage system must be considered carefully. The present case was treated with extraction of first molar to solve anterior crowding with maximum anchorage at the upper jaw and using Nance Holding Appliance.

  18. Excess Molar Volume, Viscosity and Heat Capacity for the Mixture of 1,2-Propanediol-Water at Different Temperatures%1,2-丙二醇水溶液在不同温度下的超额摩尔体积黏度和热容

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 唐多强; 靳凤民

    2003-01-01

    Experimental densities, viscosities and heat capacities at different temperatures were presented over the entire mole fraction range for the binary mixture of 1,2-propanediol and water. Density values were used in the determination of excess molar volumes, VE. At the same time, the excess viscosity was investigated. The values of VE and ηE were fitted to the Redlich-Kister equation. Good agreement was observed. The excess volumes are negative over the entire range of composition. They show an U-shaped-concentration dependence and decrease in absolute values with increase of temperature. Values of ηE are negative over the entire range of the composition, and has a trend very similar to that of VE . The analysis shows that at any temperature the specific heat of mixture is a linear function of the composition as x1>20%. All the extended lines intersect at one point. An empirical equation is obtained to calculate the specific heat to mixture at any composition and temperature in the experimental range.

  19. Estudio de volumen molar y refracción molar de miscelas de triglicéridos (triacetina, tributirina o tricaprilina y alcoholes (etanol, 1-butanol o 1-hexanol

    Directory of Open Access Journals (Sweden)

    Rodríguez Rodríguez, M.

    1992-12-01

    Full Text Available Values of molar refraction for every studied mixtures show linear plots versus molar fractions of triglyceride. Values of molar volume show this behaviour, but only for tributyrin-butanol or tricaprylin-butanol miscellas. However, in tributyrin-ethanol mixtures, volume contractions have been found, whereas triacetin-butanol and tributyrin-hexanol show volume expansions. These facts are related to the mode of being structured of the alcohol and triglyceride molecules in mixtures. A linear relationship between molar volume and temperature have been found, and also a linear dependence between the coefficient of thermal expansion at constant pressure and the molar fraction of triglyceride.

    Los valores de la refracción molar en todas las miscelas estudiadas presentan variaciones lineales frente a la fracción molar de triglicérido. la misma variación que presentan los valores del volumen molar de las miscelas tributirina y tricaprilina en butanol. Sin embargo, en las miscelas de tributirina-etanol se encuentran contracciones de volumen mientras que en las de triacetina-butanol y tributirina-hexanol expansiones, atribuidas en ambos casos a la forma de estructurarse las moléculas de alcohol y triglicérido en las miscelas. Por otra parte, se encuentra una variación lineal entre el volumen molar de las miscelas y la temperatura, y se establece una relación lineal entre el coeficiente de dilatación térmico molar a presión constante y la fracción molar de triglicérido en los cinco sistemas estudiados.

  20. Low-tmperature Heat Capacities and Standard Molar Enthalpy of Formation of 4-Nitrobenzyl Alcohol

    Institute of Scientific and Technical Information of China (English)

    MENG, Qingfen; TAN, Zhicheng; WANG, Xiaohuan; DONG, Yaping; LI, Wu; SHI, Quan

    2009-01-01

    Low-temperature heat capacities of 4-nitrobenzyl alcohol (4-NBA) have been measured by a high precision automated adiabatic calorimeter over the temperature range from 78 to 396 K. The melting temperature, the molar calculated in the range from 80 to 400 K at the interval of 5 K. The constant-volume energy and standard molar en- at T=298.15 K. The standard molar enthalpy of formation has been derived, ΔfHom(C7H7NO3, s)=-(206.49± namic quantities through a Hess thermochemical cycle.

  1. Primate molar crown formation times and life history evolution revisited.

    Science.gov (United States)

    Macho, G A

    2001-12-01

    Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life-history variables and brain size. Conversely, a firm relationship between molar formation time and life-history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life-history variables, whereas the other should not. In order to shed light on this apparent discrepancy this study analyzed all data on primate molar crown formations available in the published literature in relation to life-history variables, brain size, and female body mass. Crown formation times were found to be particularly highly correlated with both female body mass and brain size. Species that depart from the overall brain/body allometry by being relatively large-bodied, e.g., Gorilla gorilla and later Theropithecus oswaldi, also have shorter molar crown formation times than expected. The reverse is not found for species that depart from the overall brain/body allometry due to their larger brains, i.e., Homo sapiens. This finding is interpreted within an evolutionary and ecological framework. Specifically, by focusing on ecological commonalities, a scenario is proposed which may allow predictions to be made about the evolutionary history of other extinct primates also. If confirmed in future studies, crown formation time may again become a powerful tool in evolutionary enquiry. PMID:11748692

  2. Estudio de mezclas de disolventes orgánicos y triglicéridos de aceite de linaza o los ácidos grasos libres. I.- Volumen molar, refracción molar y viscosidad dinámica

    Directory of Open Access Journals (Sweden)

    Mantell Serrano, C.

    1995-06-01

    Full Text Available Measurements of molar volume, refraction index and dynamic viscosity in mixtures of fatty acids or triglycerides and trichloroethylene, tetrachloroethylene and hexane were realized. Temperature range studied was 278-313 K each 5 K. The relationship between molar volume and molar fraction show high correlation coefficient In fatty acids with trichloroethylene and tetrachloroethylene mixtures. On the other hand, hexane mixtures show little contractions of molar volume at low molar fractions. Triglyceride mixtures present important deviations with regard to the ideality of the molar volume. The adjusts obtained for the molar volume values versus temperature are acceptable, calculating the coefficients of thermal expansion of the studied mixtures. Equally, the adjust of the experimental results of viscosity for two prediction equations are studied: one of additive type and the other of parabolic type.

    Se han realizado medidas del volumen molar, índice de refracción y viscosidad dinámica en el intervalo de temperatura de 278 K a 313 K cada 5 K, a mezclas de ácidos grasos o triglicéridos con tricloroetileno, tetracloroetileno y hexano. Las mezclas de ácidos grasos con tricloroetileno y tetracloroetileno, presentan unos altos coeficientes de correlación para los valores del volumen molar frente a la fracción molar, mientras que las mezclas con hexano, a fracciones molares bajas, manifiestan una pequeña contracción del volumen molar. Las mezclas de triglicéridos presentan importantes desviaciones con respecto a la Idealidad del volumen molar. Los ajustes obtenidos para los valores del volumen molar frente a la temperatura son aceptables, determinándose los valores del coeficiente de dilatación volumétrica a presión constante de las mezclas estudiadas. Igualmente se ha estudiado el ajuste de los resultados experimentales de viscosidad a dos ecuaciones de predicción: una del tipo aditiva y otra del tipo parabólico.

  3. Pulpectomy procedures in primary molar teeth

    Directory of Open Access Journals (Sweden)

    Hany Mohamed Aly Ahmed

    2014-01-01

    Full Text Available Premature loss of primary molars can cause a number of undesirable consequences including loss of arch length, insufficient space for erupting premolars and mesial tipping of the permanent molars. Pulpectomy of primary molar teeth is considered as a reasonable treatment approach to ensure either normal shedding or a long-term survival in instances of retention. Despite being a more conservative treatment option than extraction, efficient pulpectomy of bizarre and tortuous root canals encased in roots programmed for physiologic resorption that show close proximity to developing permanent tooth buds presents a critical endodontic challenge. This article aims to provide an overview of this treatment approach, including partial and total pulpectomy, in primary molar teeth. In addition, the recommended guidelines that should be followed, and the current updates that have been developed, while commencing total pulpectomy in primary molars are discussed.

  4. Apparent Clustering and Apparent Background Earthquakes Biased by Undetected Seismicity

    CERN Document Server

    Sornette, D

    2005-01-01

    In models of triggered seismicity and in their inversion with empirical data, the detection threshold m_d is commonly equated to the magnitude m_0 of the smallest triggering earthquake. This unjustified assumption neglects the possibility of shocks below the detection threshold triggering observable events. We introduce a formalism that distinguishes between the detection threshold m_d and the minimum triggering earthquake m_0 < m_d. By considering the branching structure of one complete cascade of triggered events, we derive the apparent branching ratio n_a (which is the apparent fraction of aftershocks in a given catalog) and the apparent background source S_a that are observed when only the structure above the detection threshold m_d is known due to the presence of smaller undetected events that are capable of triggering larger events. If earthquake triggering is controlled in large part by the smallest magnitudes as several recent analyses have shown, this implies that previous estimates of the cluster...

  5. Maxillary second molar impaction in the adjacent ectopic third molar: Report of five rare cases

    Directory of Open Access Journals (Sweden)

    Bernardo Q Souki

    2015-01-01

    Full Text Available Maxillary second molar impaction in the adjacent ectopic third molar is a rare condition that practitioners might face in the field of pediatric dentistry and orthodontics. The early diagnosis and extraction of the adjacent ectopic third molar have been advocated, and prior research has reported a high rate of spontaneous eruption following third molar removal. However, some challenges in the daily practice are that the early diagnosis of this type of tooth impaction is difficult with conventional radiographic examination, and sometimes the early surgical removal of the maxillary third molar must be postponed because of the risks of damaging the second molar. The objective of this study is to report a case series of five young patients with maxillary second molar impaction and to discuss the difficulty of early diagnosis with the conventional radiographic examination, and unpredictability of self-correction.

  6. Apparent Solar Tornado - Like Prominences

    CERN Document Server

    Panasenco, Olga; Velli, Marco

    2013-01-01

    Recent high-resolution observations from the Solar Dynamics Observatory (SDO) have reawakened interest in the old and fascinating phenomenon of solar tornado-like prominences. This class of prominences was first introduced by Pettit (1932), who studied them over many years. Observations of tornado prominences similar to the ones seen by SDO had already been documented by Secchi (1877) in his famous "Le Soleil". High resolution and high cadence multiwavelength data obtained by SDO reveal that the tornado-like appearance of these prominences is mainly an illusion due to projection effects. We discuss two different cases where prominences on the limb might appear to have a tornado-like behavior. One case of apparent vortical motions in prominence spines and barbs arises from the (mostly) 2D counterstreaming plasma motion along the prominence spine and barbs together with oscillations along individual threads. The other case of apparent rotational motion is observed in prominence cavities and results from the 3D ...

  7. Treatment of ectopic first permanent molar teeth.

    LENUS (Irish Health Repository)

    Hennessy, Joe

    2012-11-01

    Ectopic eruption of the first permanent molar is a relatively common occurence in the developing dentition. A range of treatment options are available to the clinician provided that diagnosis is made early. Non-treatment can result in premature exfoliation of the second primary molar, space loss and impaction of the second premolar. This paper will describe the management of ectopic first permanent molars, using clinical examples to illustrate the available treatment options. CLINICAL RELEVANCE: This paper is relevant to every general dental practitioner who treats patients in mixed dentition.

  8. Unilateral Molar Distalization: A Nonextraction Therapy

    Directory of Open Access Journals (Sweden)

    M. Bhanu Prasad

    2012-01-01

    Full Text Available In the recent years, nonextraction treatment approaches and noncompliance therapies have become more popular in the correction of space discrepancies. One of the conventional approaches for space gaining in the arches without patient compliance is done by using certain extra oral appliances or intraoral appliance. The greatest advantage of certain appliances like fixed functional and molar distalization appliances is that they minimize the dependence on patient cooperation. Molar distalization appliances like pendulum appliance which distalizes the molar rapidly without the need of head gear can be used in patients as a unilateral space gaining procedure due to buccal segment crowding.

  9. Wormhole Thermodynamics at Apparent Horizons

    OpenAIRE

    Jamil, Mubasher; Akbar, M

    2009-01-01

    In this paper, we discuss the thermodynamic properties of the evolving Lorentzian wormhole. For the shape function $b(r) = r_{0}^2/r$, it is shown that the wormhole spacetime admits two apparent horizons, the inner and the outer one. The inner horizon expands while the outer contracts with the passage of time. Corresponding to these horizons, we have three types of wormholes, regular, extreme and the naked wormholes. Moreover, it is shown that the Einstein field equations can be rewritten as ...

  10. Third Molars: A Threat to Periodontal Health??

    OpenAIRE

    Kaveri, G. S.; Prakash, Shobha

    2011-01-01

    The third molars have received the fair amount of interest in literature. It has been blamed for problems such as—lower incisor crowding, atypical facial pain, caries etc. They are considered as ‘waste bins’ in dental practices as they are regarded as functionally non-essential. While making the clinical decision, they are given less importance and often extraction is considered to be the treatment option. Despite periodontal problems that can arise with extracted third molars, retention of t...

  11. The apparent solubility of aluminum (III) in Hanford high-level waste

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Jacob G.

    2012-12-01

    The solubility of aluminum in Hanford nuclear waste impacts on the process ability of the waste by a number of proposed treatment options. For many years, Hanford staff has anecdotally noted that aluminum appears to be considerably more soluble in Hanford waste than the simpler electrolyte solutions used as analogues. There has been minimal scientific study to confirm these anecdotal observations, however. The present study determines the apparent solubility product for gibbsite in 50 tank samples. The ratio of hydroxide to aluminum in the liquid phase for the samples is calculated and plotted as a function of total sodium molarity. Total sodium molarity is used as a surrogate for ionic strength, because the relative ratios of mono, di and trivalent anions are not available for all of the samples. These results were compared to the simple NaOH-NaAl(OH{sub 4})H{sub 2}O system, and the NaOH-NaAl(OH{sub 4})NaCl-H{sub 2}O system data retrieved from the literature. The results show that gibbsite is apparently more soluble in the samples than in the simple systems whenever the sodium molarity is greater than two. This apparent enhanced solubility cannot be explained solely by differences in ionic strength. The change in solubility with ionic strength in simple systems is small compared to the difference between aluminum solubility in Hanford waste and the simple systems. The reason for the apparent enhanced solubility is unknown, but could include. kinetic or thermodynamic factors that are not present in the simple electrolyte systems. Any kinetic explanation would have to explain why the samples are always supersaturated whenever the sodium molarity is above two. Real waste characterization data should not be used to validate thermodynamic solubility models until it can be confirmed that the apparent enhanced gibbsite solubility is a thermodynamic effect and not a kinetic effect.

  12. The apparent solubility of aluminum (III) in Hanford high-level waste.

    Science.gov (United States)

    Reynolds, Jacob G

    2012-01-01

    The solubility of aluminum in Hanford nuclear waste impacts on the processability of the waste by a number of proposed treatment options. For many years, Hanford staff has anecdotally noted that aluminum appears to be considerably more soluble in Hanford waste than the simpler electrolyte solutions used as analogues. There has been minimal scientific study to confirm these anecdotal observations, however. The present study determines the apparent solubility product for gibbsite in 50 tank samples. The ratio of hydroxide to aluminum in the liquid phase for the samples is calculated and plotted as a function of total sodium molarity. Total sodium molarity is used as a surrogate for ionic strength, because the relative ratios of mono-, di- and trivalent anions are not available for all of the samples. These results were compared to the simple NaOH-NaAl(OH)(4)-H(2)O system, and the NaOH-NaAl(OH)(4)-NaCl-H(2)O system data retrieved from the literature. The results show that gibbsite is apparently more soluble in the samples than in the simple systems whenever the sodium molarity is greater than 2M. This apparent enhanced solubility cannot be explained solely by differences in ionic strength. The change in solubility with ionic strength in simple systems is small compared to the difference between aluminum solubility in Hanford waste and the simple systems. The reason for the apparent enhanced solubility is unknown, but could include kinetic or thermodynamic factors that are not present in the simple electrolyte systems. Any kinetic explanation would have to explain why the samples are always supersaturated whenever the sodium molarity is above 2M. Real waste characterization data should not be used to validate thermodynamic solubility models until it can be confirmed that the apparent enhanced gibbsite solubility is a thermodynamic effect and not a kinetic effect. PMID:22934992

  13. Reliability of third molar development for age estimation in a Texas Hispanic population: a comparison study.

    Science.gov (United States)

    Kasper, Kathleen A; Austin, Dana; Kvanli, Alan H; Rios, Tara R; Senn, David R

    2009-05-01

    Evaluating third molars from 950 Hispanic individuals aged 12-22 years using Demirjian's schematic for crown and root formation found that Hispanic third molar development was 8-18 months faster than American Caucasians as reported by Mincer, Harris and Berryman in 1993. This represents a statistically significant increase. Earlier development was more apparent in the later stages F through H. Hispanic males reach developmental stages faster than Hispanic females and maxillary third molars reach developmental stages faster than mandibular third molars in both sexes. The earliest age observed for stages B-H (e.g., Stage H first observed at age 13.92 years in females) and the oldest age observed for Stages B-G were developed to facilitate age prediction of unknown individuals. Prediction tables for minimum and maximum age for an observed stage (e.g., if a female maxillary third molar is stage F it means she is older than 13 years) for each sex-jaw group were calculated.

  14. Ameloblastoma after surgical removal of an impacted mandibular molar. A case report.

    Science.gov (United States)

    Chindia, M L; Guthua, S W; Mwaniki, D L

    1991-04-01

    A case of an ameloblastoma diagnosed about 3 1/2 years after removal of an impacted mandibular 3rd molar is presented. The pre-operative radiographs, though poor in quality, showed an ill-defined radiolucency in relation to the tooth. This feature was not apparent to the examiners at the time of first presentation. Despite unfavourable working conditions in developing countries, a high level of suspicion should be maintained to avoid serious sequelae at a later stage. PMID:2051052

  15. Estudios físico-químicos de miscelas de aceites vegetales XIV. Volumen molar, refracción molar y viscosidad de disoluciones de estearato de metilo en ciciohexano, hexano, tetracloroetileno o tricloroetileno

    Directory of Open Access Journals (Sweden)

    Muñoz Cueto, María J.

    1991-02-01

    Full Text Available In the miscelies studied, molar volume and molar refraction values show linear dependence with the molar fraction of methyl stearate. Viscosity values fit Hildebrand's modified equation, where the "Vo" parameter is a linear function of the molar fraction of methyl stearate. Regarding with this three physico-chemical properties, the mixtures studied behave like ideal mixtures of two organic liquids without ionization.

    En todas las miscelas estudiadas los valores del volumen molar y de la refracción molar presentan variaciones lineales en función de la fracción molar de estearato de metilo. Los valores de viscosidad de las miscelas estudiadas se ajustan a la ecuación de fluidez de Hildebrand modificada, siendo su parámetro "Vo" función lineal de la fracción molar de estearato de metilo. En relación con estas tres características, el comportamiento de las miscelas estudiadas no difiere significativamente del correspondiente a una mezcla "ideal" de dos líquidos orgánicos sin ionizar.

  16. A principle to correlate extreme values of excess thermodynamic functions with partial molar quantities

    Institute of Scientific and Technical Information of China (English)

    尉志武; 刘芸; 周蕊; 薛芳渝

    2001-01-01

    Excess thermodynamic properties are widely used quantitatively for fluids. It was found that at constant temperature and pressure a molar excess quantity of a mutually miscible binary mixture at the extreme points equals the excess partial molar quantities of the two components, i.e.F1E = F2E = FmE , forming a triple cross point. The relationship is hold for properties such as en-thalpy, entropy, Gibbs free energy, and volume, and is applicable for excess functions with multi extreme points. Solutions at extreme points can be referred to as special mixtures. Particularly fora special mixture of Gibbs free energy, activity coefficients of the two components are identical.

  17. A principle to correlate extreme values of excess thermody-namic functions with partial molar quantities

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Excess thermodynamic properties are widely used quantitatively for fluids. It was found that at constant temperature and pressure a molar excess quantity of a mutually miscible binary mixture at the extreme points equals the excess partial molar quantities of the two components, i.e. , forming a triple cross point. The relationship is hold for properties such as enthalpy, entropy, Gibbs free energy, and volume, and is applicable for excess functions with multi extreme points. Solutions at extreme points can be referred to as special mixtures. Particularly for a special mixture of Gibbs free energy, activity coefficients of the two components are identical.

  18. Selective alveolar corticotomy to intrude overerupted molars.

    Science.gov (United States)

    Oliveira, Dauro Douglas; de Oliveira, Bruno Franco; de Araújo Brito, Helio Henrique; de Souza, Margareth Maria Gomes; Medeiros, Paulo José

    2008-06-01

    Orthodontic intrusion of overerupted molars in adults is challenging for most clinicians. Efficient intrusion can be achieved by combining selective alveolar corticotomies with a modified full-coverage maxillary splint to reduce surgical risks, treatment time, and costs for both orthodontists and patients. PMID:18538256

  19. Results of intentional replantation of molars

    NARCIS (Netherlands)

    Raghoebar, GM; Vissink, A

    1999-01-01

    Purpose: This study evaluated the treatment outcome of intentional replantation of molars. Patients and Methods: Twenty-nine patients were treated with intentional replantation because conventional apicoectomy was not possible. The success rate was judged by clinical and radiographic parameters. Res

  20. Ectopic molar pregnancy: a case report.

    Science.gov (United States)

    Bousfiha, Najoua; Erarhay, Sanaa; Louba, Adnane; Saadi, Hanan; Bouchikhi, Chahrazad; Banani, Abdelaziz; El Fatemi, Hind; Sekkal, Med; Laamarti, Afaf

    2012-01-01

    The incidence of hydatidiform moles is 1 per 1,000 pregnancies. Ectopic pregnancy occurs in 20 per 1,000 pregnancies. Thus, the incidence of the ectopic molar gestation is very rare. We report a case of tubal molar pregnancy diagnosed at the systematic histology exam of an ectopic pregnancy. We report the case of 32 years old nulliparus women who presented a vaginal bleeding, lower abdominal pain and 6 weeks amenorrhea corresponding to the last menstrual period. At the clinical examination, the arterial pressure was 100/60 mmHG. The gynecological examination was difficult because of lower abdominal pain. Serum gonadotropin activity was 3454 ui/l. Pelvic ultrasound revealed an irregular echogenic mass in the left adnexa. Diagnostic laparoscopy revealed a left-sided unruptured ampullary ectopic pregnancy. A left laparoscopic salpingectomy was performed. The systematic histologic test identified an ectopic partial molar pregnancy, which was confirmed by DNA ploidy image analysis. The patient was followed with weekly quantitative B-hCG titers until three successive B-hCG levels were negative. It is pertinent that clinicians take routine histological examination of tubal specimens in ectopic pregnancy very seriously in order to diagnose cases of ectopic molar gestations early and mount appropriate post treatment surveillance. PMID:22655097

  1. Stepwise excavation in a permanent molar

    DEFF Research Database (Denmark)

    Lima, Fernanda Ferruzzi; Pascotto, Renata Corrêa; Benetti, Ana Raquel

    2010-01-01

    The current study presents a 17-year clinical report of stepwise excavation and indirect pulp capping in a lower right first molar, with great dentin destruction and a lack of dentin support of the cusps. At the first appointment, indirect pulp capping with calcium hydroxide and a temporary filli...

  2. Micro‐CT analyses of apical enlargement and molar root canal complexity

    DEFF Research Database (Denmark)

    Markvart, M.; Darvann, Tron Andre; Larsen, P.;

    2012-01-01

    Markvart M, Darvann TA, Larsen P, Dalstra M, Kreiborg S, Bjørndal L. Micro‐CT analyses of apical enlargement and molar root canal complexity. International Endodontic Journal, 45, 273–281, 2012. Aim To compare the effectiveness of two rotary hybrid instrumentation techniques with focus on apical...... enlargement in molar teeth and to quantify and visualize spatial details of instrumentation efficacy in root canals of different complexity. Methodology Maxillary and mandibular molar teeth were scanned using X‐ray microcomputed tomography. Root canals were prepared using either a GT/Profile protocol or a Ra......Ce/NiTi protocol. Variables used for evaluation were the following: distance between root canal surfaces before and after preparation (distance after preparation, DAP), percentage of root canal area remaining unprepared and increase in canal volume after preparation. Root canals were classified according to size...

  3. Human dental age estimation combining third molar(s) development and tooth morphological age predictors.

    Science.gov (United States)

    Thevissen, P W; Galiti, D; Willems, G

    2012-11-01

    In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23 years, 25 gender-specific radiographs were collected within each age category of 1 year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by Köhler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals' left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R (2)) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6 % R² increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15-23 year) should only be based on third molar development.

  4. An innovative technique to distalize maxillary molar using microimplant supported rapid molar distalizer

    Directory of Open Access Journals (Sweden)

    Meenu Goel

    2013-01-01

    Full Text Available Introduction: In recent years, enhancements in implants have made their use possible as a mode of absolute anchorage in orthodontic patients. In this paper, the authors have introduced an innovative technique to unilaterally distalize the upper left 1 st molar to obtain an ideal Class I molar relationship from a Class II existing molar relationship with an indigenous designed distalizer. Clinical Innovation: For effective unilateral diatalization of molar, a novel cantilever sliding jig assembly was utilized with coil spring supported by a buccally placed single micro implant. The results showed 3 mm of bodily distalization with 1 mm of intrusion and 2° of distal tipping of upper left 1 st molar in 1.5 months. Discussion: This appliance is relatively easy to insert, well-tolerated, and requires minimal patient cooperation compared to other present techniques of molar distalization. Moreover, it is particularly useful in cases that are Class II on one side and Class I on the other, with a minor midline discrepancy and nominal overjet. Patient acceptance level was reported to be within patients physiological and comfort limits.

  5. Excess Molar Volume, Refractive Index and Viscosity of N-Butylpyridinium Tetrafluoroborate Ionic Liquid + Methanol Binary System%离子液体[BPy]BF4和甲醇二元混合体系的超额摩尔体积、折射率和黏度

    Institute of Scientific and Technical Information of China (English)

    许映杰; 黄钗英; 李浩然

    2011-01-01

    合成了室温离子液体N-丁基吡啶四氟硼酸盐([BPy]BF4),通过核磁共振1H-NMR和红外光谱IR对其结构进行了表征.在298.15 K和常压下,采用U形振荡管密度计测定[BPy]BF4-甲醇体系的密度;用阿贝尔折射仪测定了该二元混合体系在相同温度和压力下的折射率;用乌氏黏度计测定了该二元混合体系在相同温度和压力下的黏度,并由密度数据计算出超额摩尔体积(VE)、由折射率数据计算出了折射率改变值(△nD)、由黏度数据计算出了体系的黏度B系数.结果表明:[BPy]BF4-甲醇体系的VE在全浓度范围内为负值,而△nD在全浓度范围内为正值,两者均在摩尔分数x1≈0.4处出现极值;采用Redlich-Kister方程对VE、△nD与组成的关系进行了关联,最大标准偏差小于3%,说明此方程可适用于回归该二元体系上述的物性数据.由Jones-Dole方程计算出体系的黏度B系数为0.35608,这表明甲醇有效地降低了离子液体的黏度.%Room temperature ionic liquid N-butylpyridinium tetrafluoroborate ([BPy]BF4) was synthesized, and its structure was characterized and confirmed by 1H-NMR and IR. The densities and refractive indices of binary mixtures ([BPy]BF4+methanol) with different compositions were determined at T= 298.15 K and under atmospheric pressure by using a vibrating U-shaped sample tube densimeter and semi-automatic refractometer,respectively. The viscosities of the mixtures were also determined at T= 298.15 K and under atmospheric pressure by using Ubbelohde Suspended-level viscometer. Density values were used in the calculation of the excess molar volumes (V E), and the refractive indices were used to calculate the changes of refractive index (△nD). The achieved viscosities were used to calculate the viscosity B coefficient of the mixtures. The results show that the values of VE are negative over the entire composition range, while the △nD are positive. When the mole fraction of [BPy]BF4

  6. Apparent diffusion coefficient of hippocampus in patients with hippocampal sclerosis: Correlation with the volume and MRS of hippocampus%海马硬化患者海马ADC值与海马体积及磁共振波谱的相关性

    Institute of Scientific and Technical Information of China (English)

    张泉; 张云亭; 冯凯琳; 张敬; 张权

    2011-01-01

    Objective To investigate the correlation of apparent diffusion coefficient (ADC) value of hippocampus with the volume and magnetic resonance spectroscopy (MRS) of hippocampus in patients with hippocampal sclerosis (HS), and to evaluate the diagnostic value of ADC value. Methods Thirteen HS patients (HS group) of unilateral temporal lobe epilepsy (TLE) and 20 age-matched healthy subjects (control group) were studied with hippocampal ADC maps, volume measurement of hippocampus and N-acetylaspartate to choline and creatine ratios [NAA/(Cho+Cr)]. The ADC values of bilateral hippocampi and asymmetry index (AI, including AIADC, AIVOLUME and AIMRS) were measured respectively, and the correlations of ADC value with other quantitative MR measurements, age at onset and duration of epilepsy were evaluated.Results The ADC value in ipsilateral hippocampus was higher than that in contralateral side and the control group (both P <0. 001 ), and AIADC in patients with HS was also higher than that in the control group (P<0. 001). Significant correlations were found between ADC value and the volume of ipsilateral hippocampus (r=-0.854, P<0. 001), also between AIADC and AIVPLUME (r=0. 611, P<0. 05). AIADC showed positive correlation with the duration of epilepsy in HS patients (r=0. 676, P<0. 05). Conclusion The ADC value of hippocampus is helpful for the preoperative diagnosis of HS and has certain correlation with volume measurement and duration of epilepsy.%目的 探讨海马硬化(HS)患者的海马表观扩散系数(ADC)值与海马体积及磁共振波谱的相关性,并评价ADC值在HS诊断中的价值.方法 对13例单侧颞叶癫痫HS患者(HS组)和20名健康志愿者(正常对照组)行常规MR及磁共振扩散加权成像(DWI)检查,并对HS患者进行海马体积测量和磁共振波谱(MRS)检查,计算双侧海马的ADC值、标准化体积、N-乙酰天门冬氨酸/(胆碱+肌酸)[NAA/(Cho+Cr)]及不对称指数(AI,包括AIADC、AIVOLUME及AIMRS),评

  7. Dens in dente of maxillary third molar

    Directory of Open Access Journals (Sweden)

    Subramaniam Arun

    2008-01-01

    Full Text Available ′Dens in dente,′ also known as dens invaginatus, is a developmental anomaly resulting from deepening or invagination of the enamel organ into the dental papilla, which begins at the crown and often extends to the root before calcification of the dental tissues. Dens in dente commonly occur in the maxillary lateral incisor. This article reports a case of dens in dente in the maxillary third molar.

  8. Removal of Deeply Impacted Mandibular Molars by Sagittal Split Osteotomy

    Science.gov (United States)

    Isler, Sabri Cemil

    2016-01-01

    Mandibular third molars are the most common impacted teeth. Mandibular first and second molars do not share the same frequency of occurrence. In rare cases the occlusal surfaces of impacted molars are united by the same follicular space and the roots pointing in opposite direction; these are called kissing molars. In some cases, a supernumerary fourth molar can be seen as unerupted and, in this case, such a supernumerary, deeply impacted fourth molar is seen neighboring kissing molars. The extraction of deeply impacted wisdom molars from the mandible may necessitate excessive bone removal and it causes complications such as damage to the inferior alveolar nerve and iatrogenic fractures of the mandible. This case report describes the use of the sagittal split osteotomy technique to avoid extensive bone removal and protect the inferior alveolar nerve during surgical extruction of multiple impacted teeth. PMID:27429810

  9. Eruption age of permanent mandibular first molars and central incisors in the south Indian population

    Directory of Open Access Journals (Sweden)

    Gupta Rakhi

    2007-01-01

    Full Text Available Objective: The existing eruption schedules for permanent and deciduous dentition are based on studies in the Western population. Since Indians differ from Westerners racially, genetically, and environmentally, these studies fail to provide relevant guidance on the eruption schedule in the Indian population. This study aims at determining the eruption pattern of permanent mandibular molars and central incisors in the south Indian population. Materials and Methods: 10,156 apparently healthy Indian children in the age-group of 6-9 years were examined with mouth mirror and probe under adequate illumination for the status of the eruption of the permanent mandibular first molar and permanent mandibular central incisor. Pearson′s Chi-square test with Yates′ continuity correction was used to calculate the P -value for comparison of proportion between girls and boys. The values obtained in our study were compared with the standard values. The Z-test with continuity correction was used to calculate the P -value. Results: As per our study, the permanent mandibular first molars and central incisors erupted one to two years later compared to the values reported in Westerners. The earlier eruption of the permanent mandibular first molars compared to the permanent mandibular central incisors, as well as the earlier eruption of both the teeth in girls compared to boys, were in accordance with the existing literature. Conclusion: The eruption age reported by us may form a standard reference for eruption age in Indians.

  10. Excess Molar Volumes and Viscosities of Binary Mixtures of p-Xylene with Cyclohexane, n-Heptane, n-Octane,Sulfolane, N-Methyl-2-pyrrolidone and Acetic Acid at 303.15 K and 323.15 K and Atmospheric Pressure%对二甲苯与环己烷、正庚烷、正辛烷、环丁砜和N-甲基-2-吡咯烷酮和乙酸二元混合物在303.15K和323.15K的 超额体积和黏度

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 周清

    2004-01-01

    Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these data, the excess molar volume and deviations in viscosity have been calculated. The computed quantities have been fitted to the Redlich-Kister Equation to derive coefficients and estimate the standard error values. Results are discussed in terms of intermolecular interactions.

  11. STUDIES ON POLY (ETHYLENE TEREPHTHA LATE )- POLY(TETRAMETHYLENE ETHER ) MULTIBLOCK COPOLYMER. Ⅱ. THE MOLAR SEGMENT MASS AND MOLAR MASS

    Institute of Scientific and Technical Information of China (English)

    ZHAN Yongjian; YING Qicong; WU Meiyan; QIAN Renyuan

    1991-01-01

    The molar segment mass, weight-average molar mass, and molar mass distribution of a poly-(ethylene terephthalate)-poly (tetramethylene ether) multiblock copolymer sample were determined by the methods of proton nuclear magnetic resonance, low angle laser light scattering, and gel permeation chromatography.

  12. Distribution of apparent stress in western China

    Institute of Scientific and Technical Information of China (English)

    吴忠良; 黄静; 林碧苍

    2002-01-01

    Distribution of apparent stress in Chinese mainland and its surrounding regions was presented using the NEIC broadband radiated energy catalogue and the Harvard CMT catalogue from January 1987 to December 1998. Due to the limitation on the number of samples, reliable results are only for the western China. It is observed that the average apparent stress in Chinese mainland is 0.8 MPa; The maximum apparent stress to the east of the Tibetan plateau is 2.6 MPa; And the average apparent stress in the north-south seismic belt is more than one time higher than its adjacent regions. Distribution pattern of apparent stress seems to have a large-scale correlation with the cumulative energy release level in the 20th century.

  13. Radiologic study of mandibular third molar of Korean youths

    International Nuclear Information System (INIS)

    The author has made a study on the classification of the mandibular 3rd molars of Korean youths through dental radiography by means of Pell and Gregory's classification and on the prevalence of the dental caries of distal surface of the mandibular 2nd molar adjacent to the mandibular 3rd molars turned anteriorly. The results are as follow; 1. It was found that the largest case number was class I (272 cases, 52.9%) in the relation of the tooth to the ramus of the mandible and 2nd molar. 2. The mesio-angular position was the largest number (239 cases, 46.5%) in the relation of the long axis of the impacted mandibular 3rd molar to the long axis of the 2nd molar. 3. The mesio-angular position of class I was the largest number (140 cases, 27.2%) in the relation of the tooth to the ramus of the mandible and 2nd molar and the long axis of the impacted mandibular 3rd moral to the long axis of the 2nd molar. 4. The average angle of the long axis of mandibular 3rd molar in mesioangular position or horizontal position to the occlusal plane was 143 W 5. Mandibular 3rd molar with lesion such as dental cries or pericoronitis was 73 cases (14.2). 6. The caries incidence rate of the distal surface of the 2nd molar was about 3.1%.

  14. Radiologic study of mandibular third molar of Korean youths

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hyung Kyu [Dept. of Oral Radiology, College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    1982-11-15

    The author has made a study on the classification of the mandibular 3rd molars of Korean youths through dental radiography by means of Pell and Gregory's classification and on the prevalence of the dental caries of distal surface of the mandibular 2nd molar adjacent to the mandibular 3rd molars turned anteriorly. The results are as follow; 1. It was found that the largest case number was class I (272 cases, 52.9%) in the relation of the tooth to the ramus of the mandible and 2nd molar. 2. The mesio-angular position was the largest number (239 cases, 46.5%) in the relation of the long axis of the impacted mandibular 3rd molar to the long axis of the 2nd molar. 3. The mesio-angular position of class I was the largest number (140 cases, 27.2%) in the relation of the tooth to the ramus of the mandible and 2nd molar and the long axis of the impacted mandibular 3rd moral to the long axis of the 2nd molar. 4. The average angle of the long axis of mandibular 3rd molar in mesioangular position or horizontal position to the occlusal plane was 143 W 5. Mandibular 3rd molar with lesion such as dental cries or pericoronitis was 73 cases (14.2). 6. The caries incidence rate of the distal surface of the 2nd molar was about 3.1%.

  15. Bilateral lower second molar impaction in teenagers: An emergent problem?

    Directory of Open Access Journals (Sweden)

    Shinohara Elio

    2010-01-01

    Full Text Available The frequency of simultaneously impacted second and third molars in teenagers is increasing and becoming a common occurrence in adolescent oral surgery practice. The traditional treatment is the removal of the third molar by conventional access but repositioning of the surgical flap to the distal face of the first molar can predispose to complications such as pericoronitis and delayed healing of the attached gingiva. We present a case in which we use the germectomy approach to remove the impacted third molar for the eruption of the second molar through a vestibular incision. This incision offers excellent bone exposure and exit route for the third molar without disturbing the gingiva attached architecture on the distal face of the first molar providing good healing environment.

  16. Hipomineralização molar-incisivo = Molar incisor hypomineralization

    OpenAIRE

    Basso, Ana Paula

    2007-01-01

    A hipomineralização-molar incisivo (HMI) é um defeito de origem sistêmica no esmalte dentário de primeiros molares e incisivos permanentes. Nesta condição, o esmalte hipomineralizado é frágil e pode se destacar facilmente, deixando a dentina exposta e causando, assim, problemas como sensibilidade dentária e maior risco ao estabelecimento de lesões de cárie. A HMI é freqüentemente confundida com fluorose ou amelogênese imperfeita e sua prevalência varia de 3,6 a 25%. Vários fatores etiológicos...

  17. Molar Pregnancy Presents as Tubal Ectopic Pregnancy

    Directory of Open Access Journals (Sweden)

    Fatemeh Davari Tanha

    2011-01-01

    Full Text Available Hydatidiform moles are abnormal gestations characterized by the presence of hydropic changesaffecting some or all of the placental villi. Hydatidiform moles arise as a result of the fertilizationof an abnormal ovum. In this report, the patient was a 29 year old Asian woman who had inductionof ovulation with letrozol. Since the majority of molar gestations arise within the uterine cavitythus the occurrence of a hydatidiform mole within ectopic gestational tissue is rare. It is importantto differentiate a hydatidiform mole from a conventional ectopic pregnancy, particularly in infertilewomen who have a history of ovulation induction.

  18. Third molar development: measurements versus scores as age predictor.

    Science.gov (United States)

    Thevissen, P W; Fieuws, S; Willems, G

    2011-10-01

    Human third molar development is widely used to predict chronological age of sub adult individuals with unknown or doubted age. For these predictions, classically, the radiologically observed third molar growth and maturation is registered using a staging and related scoring technique. Measures of lengths and widths of the developing wisdom tooth and its adjacent second molar can be considered as an alternative registration. The aim of this study was to verify relations between mandibular third molar developmental stages or measurements of mandibular second molar and third molars and age. Age related performance of stages and measurements were compared to assess if measurements added information to age predictions from third molar formation stage. The sample was 340 orthopantomograms (170 females, 170 males) of individuals homogenously distributed in age between 7 and 24 years. Mandibular lower right, third and second molars, were staged following Gleiser and Hunt, length and width measurements were registered, and various ratios of these measurements were calculated. Univariable regression models with age as response and third molar stage, measurements and ratios of second and third molars as predictors, were considered. Multivariable regression models assessed if measurements or ratios added information to age prediction from third molar stage. Coefficients of determination (R(2)) and root mean squared errors (RMSE) obtained from all regression models were compared. The univariable regression model using stages as predictor yielded most accurate age predictions (males: R(2) 0.85, RMSE between 0.85 and 1.22 year; females: R(2) 0.77, RMSE between 1.19 and 2.11 year) compared to all models including measurements and ratios. The multivariable regression models indicated that measurements and ratios added no clinical relevant information to the age prediction from third molar stage. Ratios and measurements of second and third molars are less accurate age predictors

  19. True arterial system compliance estimated from apparent arterial compliance.

    Science.gov (United States)

    Quick, C M; Berger, D S; Hettrick, D A; Noordergraaf, A

    2000-03-01

    A new method has been developed to estimate total arterial compliance from measured input pressure and flow. In contrast to other methods, this method does not rely on fitting the elements of a lumped model to measured data. Instead, it relies on measured input impedance and peripheral resistance to calculate the relationship of arterial blood volume to input pressure. Generally, this transfer function is a complex function of frequency and is called the apparent arterial compliance. At very low frequencies, the confounding effect of pulse wave reflection disappears, and apparent compliance becomes total arterial compliance. This study reveals that frequency components of pressure and flow below heart rate are generally necessary to obtain a valid estimate of compliance. Thus, the ubiquitous practice of estimating total arterial compliance from a single cardiac cycle is suspect under most circumstances, since a single cardiac cycle does not contain these frequencies. PMID:10784093

  20. Molar Incisor Hypomineralization, Prevalence, and Etiology

    Directory of Open Access Journals (Sweden)

    Sulaiman Mohammed Allazzam

    2014-01-01

    Full Text Available Aim. To evaluate the prevalence and possible etiological factors associated with molar incisor hypomineralization (MIH among a group of children in Jeddah, Saudi Arabia. Methods. A group of 8-12-year-old children were recruited (n=267  from the Pediatric Dental Clinics at the Faculty of Dentistry, King Abdulaziz University. Children had at least one first permanent molar (FPM, erupted or partially erupted. Demographic information, children’s medical history, and pregnancy-related data were obtained. The crowns of the FPM and permanent incisors were examined for demarcated opacities, posteruptive breakdown (PEB, atypical restorations, and extracted FPMs. Children were considered to have MIH if one or more FPM with or without involvement of incisors met the diagnostic criteria. Results. MIH showed a prevalence of 8.6%. Demarcated opacities were the most common form. Maxillary central incisors were more affected than mandibular (P=0.01. The condition was more prevalent in children with history of illnesses during the first four years of life including tonsillitis (P=0.001, adenoiditis (P=0.001, asthma (P=0.001, fever (P=0.014, and antibiotics intake (P=0.001. Conclusions. The prevalence of MIH is significantly associated with childhood illnesses during the first four years of life including asthma, adenoid infections, tonsillitis, fever, and antibiotics intake.

  1. Wilcox Group Apparent Thickness, Gulf Coast (wlcxthkg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Apparent Wilcox Group thickness maps are contoured from location and top information derived from the Petroleum Information (PI) Wells database. The Wilcox...

  2. Clinical significance of computed tomography assessment for third molar surgery.

    Science.gov (United States)

    Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

    2014-07-28

    Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery. Third molar surgery is warranted when there is inadequate space for eruption, malpositioning, or risk for cyst or odontogenic tumor formation. Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues. Due to developments in medical engineering technology, computed tomography (CT) now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery. Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation, whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve. Multiple factors, including demographic, anatomic, and treatment-related factors, influence the incidence of nerve injury during or following removal of the third molar. CT assessment of the third molar prior to surgery can identify some of these risk factors, such as the absence of cortication between the mandibular third molar and the inferior alveolar canal, prior to surgery to reduce the risk for nerve damage. This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery. PMID:25071882

  3. Clinical significance of computed tomography assessment for third molar surgery

    Institute of Scientific and Technical Information of China (English)

    Kenji; Nakamori; Kei; Tomihara; Makoto; Noguchi

    2014-01-01

    Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery.Third molar surgery is warranted when there is inadequate space for eruption,malpositioning,or risk for cyst or odontogenic tumor formation.Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues.Due to developments in medical engineering technology,computed tomography(CT)now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery.Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation,whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve.Multiple factors,including demographic,anatomic,and treatment-related factors,influence the incidence of nerve injury during or following removal of the third molar.CT assessment of the third molar prior to surgery can identify some of these risk factors,such as the absence of cortication between themandibular third molar and the inferior alveolar canal,prior to surgery to reduce the risk for nerve damage.This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery.

  4. Influência da temperatura, da massa molar e da distribuição de massa molar na tensão superficial de PS, PP e PE: experimento e teoria

    Directory of Open Access Journals (Sweden)

    Moreira José C.

    2003-01-01

    Full Text Available Neste trabalho a influência da temperatura, da massa molar (n e da distribuição de massa molar (MWD na tensão superficial de poliestireno (PS foi avaliada utilizando o método da gota pendente. A influência da temperatura na tensão superficial de polipropileno isotático (i-PP e de polietileno de baixa densidade (PELBD também foi estudada aqui. As teorias de Patterson-Rastogi e Dee-Sauer foram utilizadas em conjunção com a teoria de equação de estado de Flory, Orwoll, e Vrij (FOV para prever a tensão superficial (gama utilizando dados de pressão-volume-temperatura (PVT dos polímeros. Ambas teorias prevêem que a tensão superficial diminui linearmente com o aumento da temperatura e aumenta com a massa molar concordando com os resultados experimentais. Entretanto, ambas teorias subestimam a mudança de entropia de formação de superfície por unidade de área a volume constante para sistemas poliméricos de baixa massa molar e polidisperso e subestimam o efeito da distribuição de massa molar na tensão superficial

  5. Autotransplantation of Mandibular Third Molar: A Case Report

    Directory of Open Access Journals (Sweden)

    Pabbati Ravi kumar

    2012-01-01

    Full Text Available Autogenous transplantation is a feasible, fast, and economical option for the treatment of nonsalvageable teeth when a suitable donor tooth is available. This paper presents successful autotransplantation of a mature mandibular left third molar (38 without anatomical variances is used to replace a mandibular left second molar (37. The mandibular second molar was nonrestorable due to extensive root caries and resorption of distal root. After extraction of mandibular second and third molars, root canal therapy was done for the third molar extraorally, and the tooth was reimplanted into the extracted socket of second molar site. After one year, clinical and radiographic examination revealed satisfactory outcome with no signs or symptoms suggestive of pathology. In selected cases, autogenous tooth transplantation, even after complete root formation of the donor tooth, may be considered as a practical treatment alternative to conventional prosthetic rehabilitation or implant treatment.

  6. Intrusion of overerupted molars by corticotomy and orthodontic skeletal anchorage.

    Science.gov (United States)

    Moon, Cheol-Hyun; Wee, Jin-Uk; Lee, Hyun-Sun

    2007-11-01

    This article describes the orthodontic treatment of a 26-year-old female patient with overerupted left maxillary molar teeth. Her chief complaint was that the maxillary left first and the second molar intruded into the space required for the mandibular left first and the second molars, preventing prosthodontic treatment. The authors performed a corticotomy and used orthodontic skeletal anchorage with a miniplate and orthodontic miniscrews with a head modified to provide a specially designed hook. With this approach, they were able to achieve a sufficient amount of molar intrusion without discomfort, root resorption, or extrusion of the adjacent teeth. The first molar was intruded 3.0 mm and second molar was intruded 3.5 mm during 2 months of treatment. These results have been maintained for 11 months. PMID:18004918

  7. Ceramic onlay for endodontically treated mandibular molar

    Directory of Open Access Journals (Sweden)

    Roopadevi Garlapati

    2014-01-01

    Full Text Available Restoration of endodontically treated teeth is important for the success of endodontic treatment. In full coverage restorations, maximum amount of tooth structure is compromised, so as to conserve the amount of tooth structure partial coverage restorations, can be preferred. This case report is on fabrication of a conservative tooth colored restoration for an endodontically treated posterior tooth. A 22-year-old male patient presented with pain in the mandibular left first molar. After endodontic treatment, composite material was used as postendodontic restoration. The tooth was then prepared to receive a ceramic onlay and bonded with self-adhesive universal resin cement. Ceramic onlay restoration was periodically examined up to 2 years.

  8. Molar extinction coefficients of some fatty acids

    Science.gov (United States)

    Sandhu, G. K.; Singh, Kulwant; Lark, B. S.; Gerward, L.

    2002-10-01

    The attenuation of gamma rays in some fatty acids, viz. formic acid (CH 2O 2), acetic acid (C 2H 4O 2), propionic acid (C 3H 6O 2), butyric acid (C 4H 8O 2), n-hexanoic acid (C 6H 12O 2), n-caprylic acid (C 8H 16O 2), lauric acid (C 12H 24O 2), myristic acid (C 14H 28O 2), palmitic acid (C 16H 32O 2), oleic acid (C 18H 34O 2) and stearic acid (C 18H 36O 2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement between experiment and theory.

  9. Impaction of permanent mandibular second molar: a retrospective study

    OpenAIRE

    Cassetta, Michele; Altieri, Federica; Di Mambro, Alfonso; Galluccio, Gabriella; Barbato, Ersilia

    2013-01-01

    Objective: To determine the prevalence of impacted mandibular second molar (MM2) and the association between MM2 impaction and crowding. The clinical significance of the angle between first and second mandibular molar and of the space between the first mandibular molar (MM1) and the anterior margin of mandibular ramus in MM2 impaction were also evaluated. Material and Methods: In this retrospective study , from the dental records of 2,945 caucasian young orthodontics patients, 40 subjects wit...

  10. Molar Pregnancy with a Co-Existing Viable Fetus

    OpenAIRE

    Ruya Deveer

    2014-01-01

        The aim of this study was to report the clinical features, management, and outcome of a case of molar pregnancy with a coexisting viable fetus and to review the literature. In this article, we report a case of pregnancy with diffuse placental molar change and a normal fetus which presented with hyperemesis gravidarum and hyperthyroidism. Genetic amniocentesis showed normal fetal karyotype. A healthy full-term live male infant was delivered by cesarean section. In molar preg...

  11. Outcome of Subsequent Pregnancies in Familial Molar Pregnancy

    OpenAIRE

    Masoumeh Fallahian; Forough Foroughi; Mohammad Vasei; Shahrzad Tavana; Maryam Ghanbary; Maryam Monajemzadeh; Anahita Tavana

    2013-01-01

    Familial recurrent molar pregnancy is an exceedingly rare condition, in which complete hydatidiform moles are mostly diploid but biparental in origin and the outcome of subsequent pregnancies is likely to be a hydatidiform mole or other type of reproductive loss. We previously reported a case of familial molar pregnancy (family K) comprising five affected members (four sisters and one of their cousins) each with at least one hydatidiform mole (HM). In addition to the molar pregnancies, these ...

  12. The partial molar heat capacity, expansion, isentropic, and isothermal compressions of thymidine in aqueous solution at T = 298.15 K

    International Nuclear Information System (INIS)

    Highlights: → Solution densities and sound speeds were measured for aqueous solutions of thymidine. → Partial molar volumetric properties at infinite dilution and T = 298.15 K were derived. → The partial molar isentropic and isothermal compressions are of opposite signs. → The partial molar heat capacity for thymidine at infinite dilution was determined. - Abstract: Solution densities have been determined for aqueous solutions of thymidine at T = (288.15, 298.15, 303.15, and 313.15) K. The partial molar volumes at infinite dilution, V20, obtained from the density data were used to derive the partial molar isobaric expansion at infinite dilution for thymidine at T = 298.15 K, E20{E20=(∂V20/∂T)p}. The partial molar heat capacity at infinite dilution for thymidine, Cp,20, at T = 298.15 K has also been determined. Sound speeds have been measured for aqueous solutions of thymidine at T = 298.15 K. The partial molar isentropic compression at infinite dilution, KS,20, and the partial molar isothermal compression at infinite dilution, KT,20{KT,20=-(∂V20/∂P)T}, have been derived from the sound speed data. The V20, E20, Cp,20, and KS,20 results for thymidine are critically compared with those available from the literature.

  13. Combustion energies and standard molar enthalpies of formation for the complexes of the first-row transitional metal chlorides with L-α-histidine

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Seven novel solid complexes of the first-row transitional metal with L-α-histidine were synthesized, and their compositions were determined. The constant-volume combustion energies of the complexes were measured by a precision rotation bomb calorimeter. The standard molar enthalpies of combustion and the standard molar enthalpies of formation were calculated. The results indicated thatthe plots of the standard enthalpies of formation against the atomic number of the metal show a regularity of zigzag.

  14. Viscous Cosmology and Thermodynamics of Apparent Horizon

    Institute of Scientific and Technical Information of China (English)

    M. Akbar

    2008-01-01

    @@ It is shown that the differential form of Friedmann equations of Friedman-Robertson-Walker (FRW) universe can be recast as a similar form of the first law ThdSh=dE + W dV of thermodynamics at the apparent horizon of FRW universe filled with the viscous fluid.It is also shown that by employing the general expression of temperature Th=|k|/2π=1/2π(r)A(1-(r)A/2H(r)A) associated with the apparent horizon of an FRW universe and assumed that the temperature Tm of the energy inside the apparent horizon is proportional to the horizon temperature Tm = bTh,we are able to show that the generalized second law of thermodynamics holds in the Einstein gravity provided Th-Tm/(r)A≤(p+(P)).

  15. Molar excess enthalpies at T = 298.15 K for (1-alkanol + dibutylether) systems

    Energy Technology Data Exchange (ETDEWEB)

    Mozo, Ismael; Garcia De La Fuente, Isaias [G.E.T.E.F., Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, 47071 Valladolid (Spain); Gonzalez, Juan Antonio, E-mail: jagl@termo.uva.e [G.E.T.E.F., Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, 47071 Valladolid (Spain); Cobos, Jose Carlos [G.E.T.E.F., Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, 47071 Valladolid (Spain)

    2010-01-15

    Molar excess enthalpies, H{sub m}{sup E}, at T = 298.15 K and atmospheric pressure have been measured using a microcalorimeter Tian-Calvet for the (methanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-octanol, or 1-decanol + dibutylether) systems. Experimental results have been compared with those obtained from the ERAS, DISQUAC, and Dortmund UNIFAC models. DISQUAC and ERAS yield similar H{sub m}{sup E}, results. Larger differences between experimental and calculated H{sub m}{sup E}, values are obtained from UNIFAC. ERAS represents quite accurately the excess molar volumes, V{sub m}{sup E}, of these systems. The excess molar internal energy at constant volume, U{sub V,m}{sup E}, is nearly constant for the solutions with the longer 1-alkanols. This points out that the different interactional contributions to this magnitude are counterbalanced. Interactions between unlike molecules are stronger in methanol systems. The same behaviour is observed in mixtures with dipropylether.

  16. Presence of third molars in orthodontic patients from northern Greece

    Directory of Open Access Journals (Sweden)

    Barka G

    2012-05-01

    Full Text Available Georgia Barka,1 Georgios Tretiakov,1 Theodosios Theodosiou,2 Ioulia Ioannidou-Marathiotou31School of Dentistry, 2Biostatistics, Department of Informatics, School of Natural Sciences, 3Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, GreeceObjective: The purpose of the present study was to investigate the frequency of presence of third molar teeth and their distribution in each jaw and each side, according to sex, in a group of orthodontic patients with permanent dentition from northern Greece.Methods: The sample included panoramic radiographs from 220 patients with permanent dentition (mean age 13.62 ± 1.81. The Χ2 test was used to assess the relationships between the variables, and the Fisher's exact test was used in cases where the expected frequencies in each cell were <5.Results: The frequency of third molar presence was 79.1%, and 20.9% was the frequency of third molar agenesis. Intersexual differences in the number of third molars was not statistically significant. There was a correlation between the distribution of third molars on the right and the left side (Fisher's exact test = 100.788; P = 0. The two sides showed the same tendency toward the presence or absence of third molars. A correlation was also found between the distribution of maxillary and mandibular third molars (Fisher's exact test = 24.372; P = 0. In each jaw, the presence or absence of third molars was highly related to the number of third molars found in the other jaw.Conclusion: The present results showed that in this orthodontic group of northern Greek patients, presence accounted for 79.1% and agenesis for 20.9%. No significant difference was found between the frequencies of third molar presence on the left and right sides in either the maxilla or mandible.Keywords: third molars, presence, orthodontic population, Greeks

  17. Elongational viscosity of narrow molar mass distribution polystyrene

    DEFF Research Database (Denmark)

    Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz;

    2003-01-01

    Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...

  18. Taurodont molars: Review of literature and radiological features

    International Nuclear Information System (INIS)

    Taurodontic molar teeth are present as a clinical entity in modem man. This is a suggestion that the occurrence has a racial bias. The importance of the differential diagnosis of teeth with enlarged pulp is discussed, and the possible influence of taurodontic molars on treatment planning is outlined. (author)

  19. Incomplete molar pregnancy with live coexisting fetus: a case report

    Directory of Open Access Journals (Sweden)

    Leila Pourali

    2014-03-01

    Conclusion: The rate of pregnancy complications such as hypertension, hyperthyroidism, and obstetrics hemorrhage and also the risk of Gestational Trophoblastic Neoplasm (GTN are increasing in incomplete molar pregnancy. Therefore, early diagnosis and timely treatment of molar pregnancy is very important to reduce maternal morbidity and mortality.

  20. Molar incisor hypomineralisation: clinical management of the young patient.

    LENUS (Irish Health Repository)

    Daly, Dympna

    2009-04-01

    Molar incisor hypomineralisation (MIH) is a common developmental condition resulting in enamel defects in first permanent molars and permanent incisors. It presents at eruption of these teeth. Early diagnosis is essential since rapid breakdown of tooth structure may occur, giving rise to acute symptoms and complicated treatment. The purpose of this article is to review MIH and illustrate its clinical management in young children.

  1. Application of BP neural network to semi-solid apparent viscosity simulation

    Institute of Scientific and Technical Information of China (English)

    罗中华; 张质良

    2003-01-01

    Two-layer BP neural network was designed for the semi-solid apparent viscosity simulation. The apparent viscosity simulations of Sn-15%Pb alloy and Al-4.5%Cu-1.5%Mg alloy stirred slurries were carried out. The trained BP neural network forecast the curve of the apparent viscosity versus solid volume fraction of Sn-15%Pb alloy, under the condition of shear rate, =150 s-1, and cooling rate of G=0.33 ℃/min. The simulation results are well agreement with the experimental values given in references The fitted mathematical formula of Sn-15%Pb alloy apparent viscosity, under the condition of the cooling rate of G=0.33 ℃/min, was obtained by optimization method. The results show that the precision of apparent viscosity simulation value by neural network is much better than that of its calculation value by fitted mathematical formula.

  2. The effect of particle structure on apparent density of electrolytic copper powder

    Directory of Open Access Journals (Sweden)

    K. I. POPOV

    2001-12-01

    Full Text Available The quantitative microstructural analysis and the sieve analysis of copper powder as well as the scanning electron microscopy analysis of the copper powders particles were performed. It was found that the structure of the copper powder particles determines the apparent density of copper powder. The powder particles from the same fractions of different powders occupy approximately the same volume, but the structure of metallic copper is very different. This causes the difference in apparent densities of copper powder obtained under different conditions. The more dendritic is the structure of powder particles the smaller is the apparent density of copper powder.

  3. Rubber friction on (apparently) smooth lubricated surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mofidi, M; Prakash, B [Division of Machine Elements, Luleaa University of Technology, Luleaa SE-97187 (Sweden); Persson, B N J [IFF, FZ-Juelich, 52425 Juelich (Germany); Albohr, O [Pirelli Deutschland AG, 64733 Hoechst/Odenwald, Postfach 1120 (Germany)

    2008-02-27

    We study rubber sliding friction on hard lubricated surfaces. We show that even if the hard surface appears smooth to the naked eye, it may exhibit short-wavelength roughness, which may make the dominant contribution to rubber friction. That is, the observed sliding friction is mainly due to the viscoelastic deformations of the rubber by the counterface surface asperities. The results presented are of great importance for rubber sealing and other rubber applications involving (apparently) smooth surfaces.

  4. Apparent Directional Scanning for DNA Repair

    OpenAIRE

    Zhao, Tong; Dinner, Aaron R.

    2007-01-01

    Recently it was observed that the DNA repair protein human O6-alkylguanine-DNA alkyltransferase repairs lesions at the 5′ ends of 70-nucleotide single-stranded DNA roughly threefold more frequently than lesions at the 3′ ends. Here, we introduce a coarse-grained model to show how a local asymmetry in binding kinetics (rather than thermodynamics) together with irreversible alkyl transfer can give rise to this apparent bias in sequence scanning. Exploration of the parameter space provides quant...

  5. Response of molars and non-molars to a strict supragingival control in periodontal patients

    Directory of Open Access Journals (Sweden)

    Patrícia Daniela Melchiors Angst

    2013-02-01

    Full Text Available The posterior position in the arches is one of the factors that underlies the poor prognosis of molar teeth (M. It is speculated that M do not benefit from the oral hygiene routine as well as non-molars (NM do. This study evaluated the response of M and NM to supragingival control during a 6-month period in 25 smokers (S and 25 never-smokers (NS with moderate-to-severe periodontitis. One calibrated examiner assessed visible plaque (VPI and gingival bleeding (GBI indexes, periodontal probing depth (PPD, bleeding on probing (BOP, and clinical attachment loss (CAL at days 0 (baseline, 30 and 180. At baseline, M showed significantly higher mean values of VPI (p = 0.017 and PPD (p < 0.001 compared with NM; CAL was also greater in M (p < 0.001 and was affected by smoking (p = 0.007. The reductions obtained for periodontal indicators at day 180 showed similar responses between M and NM. For CAL, M (NS 0.57 ± 0.50; S 0.67 ± 0.64 and NM (NS 0.38 ± 0.23; S 0.50 ± 0.33 reached an almost significant difference (p = 0.05. Smoking did not influence the response to treatment. Multilevel analysis revealed that, only for PDD reductions, the interaction between sites, teeth and patient was significant (p < 0.001. It was concluded that M benefit from an adequate regimen of supragingival biofilm control; therefore, supragingival condition should be considered in the prognosis of molar teeth.

  6. Human third molars development: Comparison of 9 country specific populations.

    Science.gov (United States)

    Thevissen, P W; Fieuws, S; Willems, G

    2010-09-10

    The majority of age estimation models based on third molar development are constructed on samples from populations with described and outlined origin. Due to unlike research protocols these studies can rarely be compared for the evaluation of possible geographical or ethnical influences on third molar development. The aim of this study is to evaluate country specific third molar development on standardized collected and analyzed data. On panoramic radiographs selected from subjects out of 9 country specific populations (Belgium, China, Japan, Korea, Poland, Thailand, Turkey, Saudi-Arabia and South-India) the four third molar scores were registered, according to a modified Gleiser and Hunt methodology. To obtain for each subject a (factor) score which represents the degree of third molar development, a generalized linear mixed model for multivariate ordinal data was fitted on the repeated third molar scores. Differences between countries are analyzed using gender-specific regression models for these factor scores with age and country as predictors. Comparisons between countries revealed differences in speed and onset of development. However, although reaching statistical significance, differences in actual value were small and not constant over the considered age range. In all countries, at all ages, males were ahead in third molar development compared to females.

  7. Excess molar volumes and viscosities for binary mixtures of 3-heptanone + ethyl acetate, 3-heptanone + butyl acetate, 3-heptanone + tributyl phosphate,and methyl isobutyl ketone + tributyl phosphate%3-庚酮+乙酸乙酯、3-庚酮+乙酸丁酯、3-庚酮+TBP、MIBK+ TBP二元体系的过量摩尔体积和黏度

    Institute of Scientific and Technical Information of China (English)

    杨得岭; 林晓; 曹宏斌; 李以圭; 张懿

    2012-01-01

    Densities and viscosities of four binary mixtures of 3-heptanone + ethyl acetate, 3-heptanone + butyl acetate, 3-heptanone + tributyl phosphate and methyl isobutyl ketone + tributyl phosphate were determined from 293. 15 K to 318. 15 K under atmospheric pressure using Anton Paar DMA5000 vibrating-tube densimeter and Anton Paar AMVn automated micro viscometer. From the experimental data of density and viscosity, the excess molar volumes VE and viscosity deviation △η were calculated and correlated with the Redlich-Kister polynomial equation. The viscosities of the mixtures were correlated by Orrick-Erbar (OE) group-contribution method. And the new group-contribution parameters A and B for (-O)3-P=O group were obtained. The results show that the improved Orrick-Erbar equation is able to predict the viscosities for mixtures from their pure solvents and the deviation is acceptable in engineering applications.%常压下测定了3-庚酮+乙酸乙酯、3-庚酮+乙酸丁酯、3-庚酮+磷酸三丁酯(TBP)、4-甲基-2-戊酮(MI-BK)+磷酸三丁酯4个二元体系在293.15~318.15 K下的密度和黏度值,计算了二元体系的过量摩尔体积VE和过量黏度△η,并用Redlich-Kister方程对VE和△η进行了关联.混合溶剂的黏度数据采用Orrick-Erbar(O-E)基团贡献法进行了关联和预测,增加了O-E方法中的(-O)3-P=O基团贡献值.结果表明,O-E方法可根据现有的纯溶剂的黏度数据预测得到混合溶剂的黏度,平均误差小于15%.

  8. Molar heat capacity and entropy of calcium metal

    Science.gov (United States)

    Hemingway, B.S.; Robie, R.A.; Chase, M.W.

    1997-01-01

    The heat capacity of calcium has been measured at 85 mean temperatures between T ??? 8 K and T ??? 369 K using an adiabatically-shielded calorimeter in an intermittent heating mode. At T = 298.15 K, the recommended values for the molar heat capacity, molar entropy, and molar enthalpy increment referred to T = 0 are (25.77 ?? 0.08) J??K-1??mol-1, (42.90 ?? 0.11) J??K-1??mol-1, and (5811 ?? 12) J??mol-1, respectively. The uncertainties are twice the standard deviation of the mean. ?? 1997 Academic Press Limited.

  9. Management of a Severely Submerged Primary Molar: A Case Report

    Directory of Open Access Journals (Sweden)

    Iman Parisay

    2013-01-01

    Full Text Available Ankylosis is a condition frequently associated with primary molars, wherein the ankylosed primary teeth remain in a fixed position, while the adjacent teeth continue to erupt, moving occlusally. In this case report, a five-year-old boy, who had a retained and submerged left lower second primary molar, was presented. Luxation of ankylosed primary molar was considered as a treatment approach. After four months, the tooth erupted to the occlusal level, and there was evidence of further development of a permanent successor in radiographic evaluation. After one year, tooth mobility, bone formation, and development of a permanent successor were in good condition.

  10. Hipomineralização molar-incisivo = Molar incisor hypomineralization

    Directory of Open Access Journals (Sweden)

    Basso, Ana Paula

    2007-01-01

    Full Text Available A hipomineralização-molar incisivo (HMI é um defeito de origem sistêmica no esmalte dentário de primeiros molares e incisivos permanentes. Nesta condição, o esmalte hipomineralizado é frágil e pode se destacar facilmente, deixando a dentina exposta e causando, assim, problemas como sensibilidade dentária e maior risco ao estabelecimento de lesões de cárie. A HMI é freqüentemente confundida com fluorose ou amelogênese imperfeita e sua prevalência varia de 3,6 a 25%. Vários fatores etiológicos são citados para a condição e estão freqüentemente relacionados com doenças na infância nos primeiros três anos de vida. O tratamento envolve desde a restauração dos dentes afetados com materiais adesivos ou até mesmo a extração dos mesmos, dependendo da severidade do caso.

  11. An assessment on the effects of mandibular impacted third molar surgery on the periodontium of the adjacent molar

    Directory of Open Access Journals (Sweden)

    Ramezanian M

    2003-06-01

    Full Text Available Statement of Problem: One of the important indications for the extraction of mandibular impacted third"nmolar is to preserve the periodontal health of the adjacent second molar from the destructive effects of"nplaque accumulation, acute and chronic inflammation."nAim: The purpose of this study was to determine the effect of mandibular third molar surgery on the"nPDL of the adjacent molar."nMaterials and Methods: Thirty patients, referred to the department of maxillofacial surgery, Tehran"nUniversity of Medical Sciences, were selected, based on the desirable conditions. They had no history of"nsystemic diseases and their adjacent molar was healthy. Probing depth (PD at seven points and"nattachment level (AL at three points were measured preoperatively. Standardized periapical"nradiographics were taken regularly for all patients. All the above-mentioned procedures repeated after"nthree months of surgery. Findings were analyzed by Paired t-test."nResults: A significant difference in probing depth (PD was observed before and after surgery, meaning"nthat probing depth decreased after mandibular third molar surgery. Attachment level was also decreased"npost operatively; moreover. Intrabony defects (IBD showed healing after surgery."nConclusion: Considering the limitations of the present study, impacted third molar surgery is suggested"nto prevent periodontal problems of the adjacent molar.

  12. Gravitational energy as dark energy: Cosmic structure and apparent acceleration

    CERN Document Server

    Wiltshire, David L

    2011-01-01

    Below scales of about 100/h Mpc our universe displays a complex inhomogeneous structure dominated by voids, with clusters of galaxies in sheets and filaments. The coincidence that cosmic expansion appears to start accelerating at the epoch when such structures form has prompted a number of researchers to question whether dark energy is a signature of a failure of the standard cosmology to properly account, on average, for the distribution of matter we observe. Here I discuss the timescape scenario, in which cosmic acceleration is understood as an apparent effect, due to gravitational energy gradients that grow when spatial curvature gradients become significant with the nonlinear growth of cosmic structure. I discuss conceptual issues related to the averaging problem, and their impact on the calibration of local geometry to the solutions of the volume-average evolution equations corrected by backreaction, and the question of nonbaryonic dark matter in the timescape framework. I further discuss recent work on ...

  13. Apparent resistivity of azimuthal anisotropy layered media

    Institute of Scientific and Technical Information of China (English)

    阮爱国; 毛桐恩; 李清河; 葛双成

    2002-01-01

    The electric field, equations of boundary conditions and calculation formula of apparent resistivity are derived for azimuthal anisotropy layered media with DC method based on anisotropic Ohm(s law. Taking Schlumberger symmetric system as an example and using recurrence formula of nuclear function, the paper theoretically simulates a model of four layers with the same anisotropy coefficient for each layer. The deep sounding curves of resistivity and the pattern of contours are obtained for the model. The results shows the theoretical formula of this paper is correct, the deep sounding curves not only exhibit the difference of resistivity among layers but also indicate the anisotropy characteristics of layers.

  14. THE DEBATE ON THE ORIGIN OF MOLAR-TOOTH STRUCTURES%Molar-Tooth构造成因争论分析

    Institute of Scientific and Technical Information of China (English)

    陈永红

    2006-01-01

    综述了Molar-Tooth的时空分布及其形态特征,Molar-Tooth为元古代时期全球性的一种构造现象.其成因,地质学家们已争论了一个多世纪,直到今天还未取得一致的认识.归纳前人的研究成果,初步认为Molar-Tooth的成因与藻类等生物活动有关.

  15. Cementoblastoma Relating to Right Mandibular Second Primary Molar

    Science.gov (United States)

    Manepalli, Swapna; Mohapatra, Abinash

    2016-01-01

    Cementoblastoma is a benign lesion of the odontogenic ectomesenchymal origin. It rarely occurs in primary dentition. This report describes a case of a cementoblastoma relating to the right mandibular second primary molar in a 7-year-old girl. Her panoramic radiograph revealed a well-defined radiopaque lesion with a radiolucent border extending from the distal surface of the mandibular right first primary molar to the distal surface of mandibular second primary molar. The tumor was attached to the mesial root of primary second molar and was excised along with the teeth involved and sent for histopathological evaluation, which showed irregular trabeculae of mineralized tissue interspersed with fibrovascular connective tissue, trabeculae of mineralized tissue with prominent reversal lines, and peripheral rimming of the mineralized tissue with blast cells. On a six-month follow-up, there has been no recurrence of the lesion. PMID:27738532

  16. Interacciones de la glicina en soluciones acuosas de tetrafluoroborato de 1-butil, 3-metilimidazolio a diferentes temperaturas

    OpenAIRE

    Francisco Páez Arias; Manuel Páez Meza; Alfonso Portacio Lamadrid

    2014-01-01

    Densities of glycine in aqueous solutions of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate were determined at temperatures ranging from 283.15 to 313.15 K. The apparent molar volume, infinite dilution apparent molar volume, second derivative of the infinite dilution partial molar volume with respect to temperature, partial molar volume of transfer at infinite dilution, and the number of hydration were determined. It was found that the apparent molar volume at infinite dilution wa...

  17. Thermodynamics of aqueous mixtures of nonelectrolytes. 1. Excess volumes of water +. gamma. -butyrolactone mixtures at several temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, M.O.; Al-Madafl, S.H.F.; Awwad, A.M.

    1987-04-01

    Excess molar volumes of water + ..gamma..-butyrolactone mixtures were obtained from precise density measurements over the entire mole fraction range and at 10K intervals from 288.15 to 318.15K. Partial molar excess volumes, excess coefficients of thermal expansion, and partial molar excess expansibilities at 298.15K were derived from the results. The significance of these results is discussed in terms of the structural changes in the mixtures.

  18. A generational comparison of changes in mandibular third molars.

    OpenAIRE

    Tanaka T; Morimoto Y; Ohba T

    1999-01-01

    Due to recent increases in the number of cases of embedded mandibular third molars, the Department of Dental Radiology, Kyushu Dental College decided to investigate generational differences in their occurrence. For the purpose of investigation, 670 panoramic radiographs, obtained from two different generations (1970s and 1999s) of Kyushu Dental College students, wer used. There were significant statistical differences in the angle of eruption of the third molar between the 1970s and 1990s gro...

  19. Fusion or gemination? An unusual mandibular second molar

    Directory of Open Access Journals (Sweden)

    Angela Jordão Camargo

    2016-01-01

    Full Text Available Fusion and gemination is not an uncommon finding and affected most primary dentition and the permanent maxillary incisors. These changes can develop a series of complication. A 11-year-old male presented radiography finding: an unusual mandibular second molar. A well-documented case brings a challenge for radiologists classify between fusion and gemination. In conclusion, this alteration although common in other regions, there are no case in the literature involving “second and third” molar.

  20. Genetic integration of molar cusp size variation in baboons

    OpenAIRE

    Koh, Christina; BATES, ELIZABETH; Broughton, Elizabeth; Do, Nicholas T.; Fletcher, Zachary; Mahaney, Michael C.; Hlusko, Leslea J.

    2010-01-01

    Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded o...

  1. The orthodontic extraction of permanent molars: a literature review.

    Science.gov (United States)

    Chua, Emilia S L; Felicita, A Sumathi

    2015-05-01

    The most common cause of dental crowding is the presence of an arch-length--tooth-size discrepancy. Conventional methods of gaining space in orthodontics involve the extraction of teeth, often premolars. However, there are a number of clinical situations in which the extraction of permanent molars might be considered. This paper highlights the indications, advantages, disadvantages and timing of the extraction of the first, second and third permanent molars in the treatment of a crowded malocclusion. PMID:26219149

  2. A bracket design proposal for the first molar

    Directory of Open Access Journals (Sweden)

    Roberto Scalon

    2010-07-01

    Full Text Available Introduction: The advent of bracket bonding simplified the assembly of orthodontic braces, besides giving more comfort to the patient and decreasing the risk of decalcification. However, there is no first molar bracket with accessory tube and hooks in the market, except for the convertible type.Objective:To present a patent for utility model of a bracket Roth prescription, Straight-Wire technique for first molar, in order to facilitate orthodontic treatment where there is a need for placing accessories in second molars.Material and methods:This patent consists of a molar bracket for bonding, which contains a retentive base for this, similar to the bracket used in the Edgewise technique,with fins for placing alastic or metal ligature,but containing pre-angles and torques as the tubes of the molar Straight-Wire technique with Roth prescription.It also includes an accessory tube for placing arches or cantilevers and hooks for placing elastics.Results and conclusion:With this bracket design proposal it is possible to obtain an accessory that facilitates the inclusion of the second molar in the assembly of the orthodontic brace without the use of bands.Moreover, this bracket has fins for placing ligatures,accessory tube for placing arches or cantilevers and hooks for placing elastics.

  3. Standard molar enthalpy of formation of methoxyacetophenone isomers

    International Nuclear Information System (INIS)

    Highlights: • Experimental and computational energetic study of methoxyacetophenone isomers. • Enthalpies of formation and phase transition determined by calorimetric techniques. • Quantum chemical calculations allowed estimation of enthalpies of formation. • Structure and energy correlations were established. - Abstract: Values of the standard (po = 0.1 MPa) molar enthalpy of formation of 2′-, 3′- and 4′-methoxyacetophenones were derived from their standard molar energy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation/vaporization of the compounds studied. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and the standard molar enthalpies for the phase transition. The results obtained are −(232.0 ± 2.5), −(237.7 ± 2.7) and −(241.1 ± 2.1) kJ · mol−1 for 2′-, 3′- and 4′-methoxyacetophenone, respectively. Standard molar enthalpies of formation were also estimated from different methodologies: the Cox scheme as well as two different computational approaches using density functional theory-based B3LYP and the multilevel G3 methodologies

  4. Association of early CT abnormalities, infarct size, and apparent diffusion coefficient reduction in acute ischemic stroke

    NARCIS (Netherlands)

    Somford, DM; Marks, MP; Thijs, VN; Tong, DC

    2004-01-01

    BACKGROUND AND PURPOSE: Diffusion-weighted (DW) imaging is more sensitive for early ischemia than CT, and apparent diffusion coefficient (ADC) mapping permits quantification of the severity of cytotoxic edema. We examined the relationship between early CT findings, ischemic lesion volume on DW image

  5. Distal caries of the second molar in the presence of a mandibular third molar - a prevention protocol.

    Science.gov (United States)

    Toedtling, V; Coulthard, P; Thackray, G

    2016-09-23

    Objectives The objectives of the prospective study were to establish the prevalence of distal caries (DC) in the mandibular second molar and to assess the outcomes of these diseased teeth in our population. Further aims were to identify associated risk factors and to design a protocol for prevention.Methods Clinical and radiographic data from 210 consecutive patients were ascertained over a three-month period. The sample population included all patients who had been referred to a hospital oral surgery department for a lower wisdom tooth assessment.Results A total of 224 mandibular third molars were included and assessed. The prevalence of caries affecting the distal aspect of the second molar was 38% (n = 85) in this population. In 18% of patients there was evidence of early enamel caries. Fifty-eight percent of caries was managed with restorative treatment but 11% of patients required second molar extraction and 13% of patients required the removal of the second and third molars. The prevalence of distal caries was significantly higher in patients with partially erupted wisdom teeth positioned below the amelocemental junction (P correlation coefficient were used to verify the association between the tested variables.Conclusion This study demonstrates that the eruption status, type of angulation and the nature of tooth contact between both molars are useful disease predictors which can be used to indicate the likelihood of a caries process occurring on the distal aspect of the second mandibular molar. If patients' third molar teeth are not removed then consideration needs to be given to prevention and regular monitoring. PMID:27659630

  6. On the frequency-apparent magnitude relations

    Energy Technology Data Exchange (ETDEWEB)

    Tinti, S.; Rimondi, R.; Mulargia, F.

    1987-08-01

    The ''apparent magnitude'' of an earthquake is the observed magnitude value and differs from the true magnitude in virtue of the experimental error. If the error is assumed to be normally distributed with standard deviation sigma, the probability distributions of the two magnitudes may be proven to be in a rather simple relationship, at least for the cases of seismological interest. In fact, there is a significant interval of magnitudes where the suggested approximation in the text holds. The main consequence is that, independently of the assumed basic distribution of the true magnitude, the exceedence frequencies appearing from the observed data are larger than the true ones and therefore their values should be corrected by an appropriate reducing factor.

  7. Distribution of apparent magnetization for Asia

    Institute of Scientific and Technical Information of China (English)

    徐元芳; 安振昌; 黄宝春; V.P.Golovkov; N.M.Rotanova; A.L.Kharitonov

    2000-01-01

    Magsat total field anomalies over Asia were used to construct an equivalent magnetization model, which represents the apparent magnetization distribution within an equivalent layer 40 km thick and correlates well with large-scale tectonics, for example, the Kazakhstan, Tarim, Yangtze, India, Sino-Korea and Indochina blocks. The basin, plain, sea basin, and islands are delineated by magnetization lows whereas the plateau and marine ridge correspond to magnetization highs. The boundary between Tibetan Plateau and India marked by a strong gradient along its length coincides with the Yarlung Zangbo River fault roughly. The Tanlu fault belt is the boundary between positive and negative anomalies. This boundary stretches in southwest direction and joins Sanjiang fault belt. The boundary between the Southeast China block and the Yangtze block is also clearly delineated by the magnetization anomalies. Generally, the magnetization boundaries are consistent with the collisional suture of blocks.

  8. Cosmological and black hole apparent horizons

    CERN Document Server

    Faraoni, Valerio

    2015-01-01

    This book overviews the extensive literature on apparent cosmological and black hole horizons. In theoretical gravity, dynamical situations such as gravitational collapse, black hole evaporation, and black holes interacting with non-trivial environments, as well as the attempts to model gravitational waves occurring in highly dynamical astrophysical processes, require that the concept of event horizon be generalized. Inequivalent notions of horizon abound in the technical literature and are discussed in this manuscript. The book begins with a quick review of basic material in the first one and a half chapters, establishing a unified notation. Chapter 2 reminds the reader of the basic tools used in the analysis of horizons and reviews the various definitions of horizons appearing in the literature. Cosmological horizons are the playground in which one should take baby steps in understanding horizon physics. Chapter 3 analyzes cosmological horizons, their proposed thermodynamics, and several coordinate systems....

  9. Field signature for apparently superluminal particle motion

    CERN Document Server

    Land, Martin

    2016-01-01

    In the context of Stueckelberg's covariant symplectic mechanics, Horwitz and Aharonovich have proposed a simple mechanism by which a particle traveling below light speed almost everywhere may exhibit a transit time that suggests superluminal motion. This mechanism, which requires precise measurement of the particle velocity, involves a subtle perturbation affecting the particle's recorded time coordinate caused by virtual pair processes. The Stueckelberg framework is particularly well suited to such problems, because it permits pair creation/annihilation at the classical level. In this paper, we study a trajectory of the type proposed by Horwitz and Aharonovich, and derive the Maxwell 4-vector potential associated with the motion. We show that the resulting fields carry a signature associated with the apparent superluminal motion, providing an independent test for the mechanism that does not require direct observation of the trajectory, except at the detector.

  10. Prevalence of missing and impacted third molars in adults aged 25 years and above

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yun Hoa; Cho, Bong Hae [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yansan (Korea, Republic of)

    2013-12-15

    The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent second molars. A greater percentage of men than women retained at least one third molar. The incidence of third molars decreased with increasing age. The incidence of partially impacted third molars greatly declined after the age of 30. Vertically impacted maxillary third molars and horizontally impacted mandibular third molars were most frequent in all age groups. Among the maxillary third molars, those impacted below the cervical line of the second molar were most frequent in all age groups, and among the mandibular third molars, deeply impacted third molars were most frequent in those aged over 40. Dental caries was the most common radiographic lesion of the third molars. Mesioangularly impacted third molars showed radiographic lesions in 13 (9.5%) adjacent maxillary second molars and 117 (27.4%) mandibular second molars. The number of remaining third molars decreased and the percentage of Class C depth increased with age. Caries was the most frequent lesion in third molars. Partially impacted mesioangular third molars showed a high incidence of caries or periodontal bone loss of the adjacent second molar. Regular oral examination will be essential to keep asymptomatic third molars in good health.

  11. Erupted complex odontoma delayed eruption of permanent molar.

    Science.gov (United States)

    Ohtawa, Yumi; Ichinohe, Saori; Kimura, Eri; Hashimoto, Sadamitsu

    2013-01-01

    Odontomas, benign tumors that develop in the jaw, rarely erupt into the oral cavity. We report an erupted odontoma which delayed eruption of the first molar. The patient was a 10-year-old Japanese girl who came to our hospital due to delayed eruption of the right maxillary first molar. All the deciduous teeth had been shed. The second premolar on the right side had erupted, but not the first molar. Slight inflammation of the alveolar mucosa around the first molar had exposed a tooth-like, hard tissue. Panoramic radiography revealed a radiopaque mass indicating a lesion approximately 1 cm in diameter. The border of the image was clear, and part of the mass was situated close to the occlusal surface of the first molar. The root of the maxillary right first molar was only half-developed. A clinical diagnosis of odontoma was made. The odontoma was subsequently extracted, allowing the crown of the first molar to erupt almost 5 months later. The dental germ of the permanent tooth had been displaced by the odontoma. However, after the odontoma had been extracted, the permanent tooth was still able to erupt spontaneously, as eruptive force still remained. When the eruption of a tooth is significantly delayed, we believe that it is necessary to examine the area radiographically. If there is any radiographic evidence of a physical obstruction that might delay eruption, that obstruction should be removed before any problems can arise. Regular dental checkups at schools might improve our ability to detect evidence of delayed eruption earlier. PMID:24521551

  12. Erupted complex odontoma delayed eruption of permanent molar.

    Science.gov (United States)

    Ohtawa, Yumi; Ichinohe, Saori; Kimura, Eri; Hashimoto, Sadamitsu

    2013-01-01

    Odontomas, benign tumors that develop in the jaw, rarely erupt into the oral cavity. We report an erupted odontoma which delayed eruption of the first molar. The patient was a 10-year-old Japanese girl who came to our hospital due to delayed eruption of the right maxillary first molar. All the deciduous teeth had been shed. The second premolar on the right side had erupted, but not the first molar. Slight inflammation of the alveolar mucosa around the first molar had exposed a tooth-like, hard tissue. Panoramic radiography revealed a radiopaque mass indicating a lesion approximately 1 cm in diameter. The border of the image was clear, and part of the mass was situated close to the occlusal surface of the first molar. The root of the maxillary right first molar was only half-developed. A clinical diagnosis of odontoma was made. The odontoma was subsequently extracted, allowing the crown of the first molar to erupt almost 5 months later. The dental germ of the permanent tooth had been displaced by the odontoma. However, after the odontoma had been extracted, the permanent tooth was still able to erupt spontaneously, as eruptive force still remained. When the eruption of a tooth is significantly delayed, we believe that it is necessary to examine the area radiographically. If there is any radiographic evidence of a physical obstruction that might delay eruption, that obstruction should be removed before any problems can arise. Regular dental checkups at schools might improve our ability to detect evidence of delayed eruption earlier.

  13. Cholesterol-induced variations in the volume and enthalpy fluctuations of lipid bilayers.

    Science.gov (United States)

    Halstenberg, S; Heimburg, T; Hianik, T; Kaatze, U; Krivanek, R

    1998-07-01

    The sound velocity and density of suspensions of large unilamellar liposomes from dimyristoylphosphatidylcholine with admixed cholesterol have been measured as a function of temperature around the chain melting temperature of the phospholipid. The cholesterol-to-phospholipid molar ratio xc has been varied over a wide range (0 temperature dependence of the sound velocity number, of the apparent specific partial volume of the phospholipid, and of the apparent specific adiabatic compressibility have been derived from the measured data. These data are particularly discussed with respect to the volume fluctuations within the samples. A theoretical relation between the compressibility and the excess heat capacity of the bilayer system has been derived. Comparison of the compressibilities (and sound velocity numbers) with heat capacity traces display the close correlation between these quantities for bilayer systems. This correlation appears to be very useful as it allows some of the mechanical properties of membrane systems to be calculated from the specific heat capacity data and vice versa. PMID:9649386

  14. Uterine rupture following incomplete molar pregnancy: a case report

    Directory of Open Access Journals (Sweden)

    Pourali L

    2013-03-01

    Full Text Available Background: In molar pregnancy, when hydatidiform changes are local and some embryonic components are observed, the term of partial mole is used. The risk of persistent trophoblastic tumor after partial mole is much lower than complete mole. In this persistent cases almost all are non metastatic. The aim of this study is to report a case of uterine rupture following incomplete molar pregnancy.Case presentation: The patient was a 26 year old woman with obstetric history of an abortion and one molar pregnancy and no child. She was referred to emergency unit in Ghaem University Hospital, Mashhad, Iran in May 2011. She had an evacuation curettage following molar pregnancy three months before and without any follow up visit. The patient was referred to emergency unit with hemorrhagic shock. She immediately underwent laparotomy. The uterine fundal rupture was repaired and evacuation curettage performed. In post operative evaluation, she had a nine millimeter metastatic nodule in base of right Lung. As a patient in low risk stage III, she received weekly intramuscular methotrexate (40mg/m2 for six courses. In follow up visit -hCG titer was negative (<10miu/ml at 5th week. Conclusion: In cases of in complete molar pregnancy risk of metastasis is very low. Serial beta-hCG titer is the most accurate method for detection of persistent gestational trophoblastic disease (GTN. In neglected cases like this case preservation of ruptured uterus in GTN is possible.

  15. Iatrogenic displacement of impacted third molar. Case report

    Directory of Open Access Journals (Sweden)

    Konstantinos TSIKLAKIS

    2013-08-01

    Full Text Available Peri-operative complications may occur during the surgical extraction of impacted mandibular third molars such as the iatrogenic displacement of the whole tooth or a tooth fragment in to the adjacent anatomical structures. The purpose of this case report is to present the diagnosis and treatment planning, as well as the surgical management required for the removal of a 3rd molar displaced in the soft tissues of the floor of the mouth. A 38-year old male patient presented to the Dental School, complaining of pain around the left submandibular area that started three months after the extraction of the impacted mandibular left third molar. At the radiographic examination the tooth was detected in the soft tissues of the floor of the mouth and in close proximity to the lingual plate. It is noteworthy that the patient was under the assumption that the tooth had been extracted successfully. Radiographically the tooth appeared at an 180° turnaround from its original position. Surgical extraction of the displaced third molar took place under local anaesthesia. No post-operative complications were reported. Thorough clinical and radiographic examination, as well as competency at surgical procedures are prerequisites for the appropriate surgical management of impacted third molars.

  16. Histopathologic Evaluation of Follicular Tissues Associated with Impacted Third Molars

    Directory of Open Access Journals (Sweden)

    M. Khorasani

    2008-06-01

    Full Text Available Objective: The aim of the present study was to histopathologically evaluate follicular tissues of third molars with pericoronal radiolucenciesof less than 2 millimeters.Materials and Methods: In this descriptive analytic study, 100 impacted third molars with normal follicular spaces were removed and their pericoronaltissues submitted for histopathologic examination. Different characteristicsof the epithelium and connective tissue were evaluated in all cases. Statisti-cal analysis was performed using chi square and Mann-Whitney tests.Results: In our study sample, 74% of the patients were female and 26% were male, ranging in age from 13 to 54 years (mean, 25.3 years. Lining epithelium was observed in 69% of the specimens of which 31%, 23% and 14% was cuboidal, squamous and columnar, respectively. A significant re-lationship was found between the presence of squamous epithelium and pa-tient age (P<0.05. Nonspecific chronic inflammation was the only patho-logic finding observed in 44% of the specimens. Inflammation was signifi-cantly associated with age and squamous metaplasia (P<0.05.Conclusion: Considering that pathologic lesions were not observed in anyof the studied cases, unerupted third molars should not be removed unless there is a clinical indication to do so, or in case the impacted molar shows evidence of pathological changes. Follow-up is suggested for asympto-matic impacted third molars.

  17. Apparent life-threatening event in infancy

    Science.gov (United States)

    Choi, Hee Joung

    2016-01-01

    An apparent life-threatening event (ALTE) is defined as the combination of clinical presentations such as apnea, marked change in skin and muscle tone, gagging, or choking. It is a frightening event, and it predominantly occurs during infancy at a mean age of 1–3 months. The causes of ALTE are categorized into problems that are: gastrointestinal (50%), neurological (30%), respiratory (20%), cardiovascular (5%), metabolic and endocrine (2%–5%), or others such as child abuse. Up to 50% of ALTEs are idiopathic, where the cause cannot be diagnosed. Infants with an ALTE are often asymptomatic at hospital and there is no standard workup protocol for ALTE. Therefore, a detailed initial history and physical examination are important to determine the extent of the medical evaluation and treatment. Regardless of the cause of an ALTE, all infants with an ALTE should require hospitalization and continuous cardiorespiratory monitoring and evaluation for at least 24 hours. The natural course of ALTEs has seemed benign, and the outcome is generally associated with the affected infants' underlying disease. In conclusion, systemic diagnostic evaluation and adequate treatment increases the survival and quality of life for most affected infants.

  18. Radiographic Evaluation of Root and Canal Morphologies of Third Molar Teeth in Iranian Population

    OpenAIRE

    Faramarzi; Shahriari; Shokri; Vossoghi; Yaghoobi

    2013-01-01

    Background Root and canal morphology of teeth has a significant role in endodontic treatment success. Third molars have strategic roles after losing first and second molars. Objectives This study investigated the morphology of permanent third molar using radiography in Dentistry University of Hamadan during 2011. Materials and Methods In this experimental study, 352 extracted molar...

  19. Chain-length-dependent impact of band broadening on the molar-mass determination of synthetic polymers via size-exclusion chromatography.

    Science.gov (United States)

    Wolpers, Arne; Vana, Philipp

    2016-08-01

    The impact of band-broadening (BB) on the molar-mass determination of synthetic polymers via size-exclusion chromatography (SEC) is systematically studied. BB is simulated using the exponentially modified Gaussian (EMG) model, which combines the two inherent and distinct characteristics contributing to BB in SEC: symmetric Gaussian broadening and asymmetric skewing. It is demonstrated that BB both during the measurement of the analyte itself and during the calibration process has an individual impact on molar-mass determination. In this context, particularly skewing leads to a chain-length-dependent underestimation of molar masses, with deviations of the apparent from the true ones of only a few percent for low molar masses to up to 20% for high ones for reasonable extents of BB. The impact is shown to be independent of the shape of the analyte⬢s molar-mass distribution (MMD) and affects broad and multimodal MMDs similarly to narrow and unimodal ones. As a consequence, strategies are presented for a comprehensive quantitative correction of the observed effects, which may find their application in refined SEC software packages. The potential impact of the findings on general conceptions of repeatability and reproducibility within SEC experiments is discussed. PMID:27393628

  20. The partial molar heat capacity, expansion, isentropic, and isothermal compressions of thymidine in aqueous solution at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Hedwig, Gavin R., E-mail: G.Hedwig@massey.ac.nz [Institute of Fundamental Sciences-Chemistry, Massey University, Private Bag 11222, Palmerston North (New Zealand); Jameson, Geoffrey B. [Institute of Fundamental Sciences-Chemistry, Massey University, Private Bag 11222, Palmerston North (New Zealand); Hoiland, Harald [Department of Chemistry, University of Bergen, N-5020 Bergen (Norway)

    2011-12-15

    Highlights: > Solution densities and sound speeds were measured for aqueous solutions of thymidine. > Partial molar volumetric properties at infinite dilution and T = 298.15 K were derived. > The partial molar isentropic and isothermal compressions are of opposite signs. > The partial molar heat capacity for thymidine at infinite dilution was determined. - Abstract: Solution densities have been determined for aqueous solutions of thymidine at T = (288.15, 298.15, 303.15, and 313.15) K. The partial molar volumes at infinite dilution, V{sub 2}{sup 0}, obtained from the density data were used to derive the partial molar isobaric expansion at infinite dilution for thymidine at T = 298.15 K, E{sub 2}{sup 0}{l_brace}E{sub 2}{sup 0}=({partial_derivative}V{sub 2}{sup 0}/{partial_derivative}T){sub p}{r_brace}. The partial molar heat capacity at infinite dilution for thymidine, C{sub p,2}{sup 0}, at T = 298.15 K has also been determined. Sound speeds have been measured for aqueous solutions of thymidine at T = 298.15 K. The partial molar isentropic compression at infinite dilution, K{sub S,2}{sup 0}, and the partial molar isothermal compression at infinite dilution, K{sub T,2}{sup 0}{l_brace}K{sub T,2}{sup 0}=-({partial_derivative}V{sub 2}{sup 0}/{partial_derivative}P){sub T}{r_brace}, have been derived from the sound speed data. The V{sub 2}{sup 0}, E{sub 2}{sup 0}, C{sub p,2}{sup 0}, and K{sub S,2}{sup 0} results for thymidine are critically compared with those available from the literature.

  1. Pendulum Therapy of Molar Distalization in Mixed Dentition.

    Science.gov (United States)

    Patil, Raju Umaji; Prakash, Amit; Agarwal, Anshu

    2016-01-01

    Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient's compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a successful treatment method of class II malocclusion with pendulum appliance in mixed dentition phase. Distalization of maxillary molar was done, followed by guidance of canine impaction orthodontically and other dental correction using 0.022 MBT appliances. Posttreatment results were stable and remarkable. How to cite this article: Patil RU, Prakash A, Agarwal A. Pendulum Therapy of Molar Distalization in Mixed Dentition. Int J Clin Pediatr Dent 2016;9(1):67-73.

  2. COMPLICATIONS AFTER EXTRACTION OF IMPACTED THIRD MOLARS - LITERATURE REVIEW

    Directory of Open Access Journals (Sweden)

    Elitsa G. Deliverska

    2016-07-01

    Full Text Available Third molar surgery is the most common procedure performed by oral and maxillofacial surgeons worldwide. This article addresses the incidence of specific complications and, where possible, offers a preventive or management strategy. Complications, such as pain, dry socket, swelling, paresthesia of the lingual or inferior alveolar nerve, bleeding, and infection are most common. Factors thought to influence the incidence of complications after third molar removal include age, gender, medical history, oral contraceptives, presence of pericoronitis, poor oral hygiene, smoking, type of impaction, relationship of third molar to the inferior alveolar nerve, surgical time, surgical technique, surgeon experience, use of perioperative antibiotics, use of topical antiseptics, use of intra-socket medications, and anaesthetic technique. For the general dental practitioner, as well as the oral and maxillofacial surgeon, it is important to be familiar with all the possible complications after this procedure. This improves patient education and leads to prevention, early recognition and management.

  3. Microbiology of the pericoronal pouch in mandibular third molar pericoronitis.

    Science.gov (United States)

    Leung, W K; Theilade, E; Comfort, M B; Lim, P L

    1993-10-01

    The microorganisms associated with mandibular third molar pericoronitis were investigated using direct microscopy and anaerobic culture method. The pericoronal pouch was sampled with paper points in A) 8 patients without mandibular third molar pericoronitis and B) 6 patients with mandibular third molar pericoronitis. Under the microscope, the microflora was found to be a complex mixture comprising gram-positive and gram-negative cocci, rods and filaments (including fusiform and curved rods), motile rods and spirochetes. Significantly higher proportions of motile, gram-negative rods were found in group B than in group A. The predominant cultivable microflora of 9 samples: A (4) and B (5) comprised several species of facultative and obligate anaerobic bacteria, namely Peptostreptococcus, Streptococcus, Actinomyces, Eubacterium, Propionibacterium, Veillonella, Porphyromonas, Prevotella, Bacteriodes, Fusobacterium, Campylobacter, Staphylococcus, Stomatococcus, Lactobacillus, Neisseria, Capnocytophaga, Haemophilus, Selenomonas and Centipeda species. The microflora in pericoronitis appeared similar to that of diseased periodontal pockets.

  4. First permanent molar root development arrest associated with compound odontoma.

    Science.gov (United States)

    Gunda, Sachin A; Patil, Anil; Varekar, Aniruddha

    2013-07-04

    Trauma or infection to the primary tooth may have deleterious effects on the underlying developing tooth buds. Anatomically the root apices of primary teeth are in close proximity to the developing permanent tooth buds; hence spread of infection originating from pulp necrosis of primary tooth may not only affect the underlying tooth bud but may also affect the adjacent tooth buds. The extent of malformation depends on the developmental stage of tooth or the age of patient. Presented here is a rare case of complete arrest of maxillary first permanent molar root growth due to spread of periapical infection originating from second primary molar leading to failure of its eruption and finally extraction. Histopathlogical analysis revealed compound odontoma associated with maxillary first permanent molar.

  5. Pendulum Therapy of Molar Distalization in Mixed Dentition.

    Science.gov (United States)

    Patil, Raju Umaji; Prakash, Amit; Agarwal, Anshu

    2016-01-01

    Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient's compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a successful treatment method of class II malocclusion with pendulum appliance in mixed dentition phase. Distalization of maxillary molar was done, followed by guidance of canine impaction orthodontically and other dental correction using 0.022 MBT appliances. Posttreatment results were stable and remarkable. How to cite this article: Patil RU, Prakash A, Agarwal A. Pendulum Therapy of Molar Distalization in Mixed Dentition. Int J Clin Pediatr Dent 2016;9(1):67-73. PMID:27274159

  6. Fibrous epulis associated with impacted lower right third molar

    Directory of Open Access Journals (Sweden)

    Ni Putu Mira Sumarta

    2009-12-01

    Full Text Available Background: Epulis or epulides are lesions associated with gingival tissues. Fibrous epulis is a type of hyperplastic fibrous tissue mass located at the gingival which is slow growing, painless, having same color as the oral mucosa and firm on palpation. Anterior regions of the oral cavity are the frequently affected sites as these areas are more prone to be affected by calculus deposition and poor plaque control due to frequent teeth malposition. Removal of any irritating factors and excision of the lesion are the usual treatments. Purpose: This case report presents a rare case of fibrous epulis which occurred in the posterior region of the oral cavity and associated with impacted lower third molar. Case: A case of fibrous epulis at the lower right third molar area of three months duration is presented. The mass was slow growing, painless and on examination it was a pedunculated mass overlying the unerupted lower right third molar, having same color with the oral mucosa and firm on palpation. Clinically, the lesion was diagnosed as fibrous epulis associated with impacted lower right third molar. Case management: The treatment were surgical excision of the epulis and removal of the lower right third molar. The histopathology result showed tissue with squamous epithelial lining, achanthotic fibrous connective tissue, mononuclear inflammatory cells and few capillaries without signs of malignancy. This is consistent with the diagnosis of fibrous epulis. Conclusion: Fibrous epulis, although frequently occurred at the anterior region of the oral cavity, may rarely grow at the area of lower third molar. This phenomenon supports the theory that epulis can grow on any surface of oral mucous membrane as long as local irritants are present.

  7. The average free volume model for liquids

    CERN Document Server

    Yu, Yang

    2014-01-01

    In this work, the molar volume thermal expansion coefficient of 59 room temperature ionic liquids is compared with their van der Waals volume Vw. Regular correlation can be discerned between the two quantities. An average free volume model, that considers the particles as hard core with attractive force, is proposed to explain the correlation in this study. A combination between free volume and Lennard-Jones potential is applied to explain the physical phenomena of liquids. Some typical simple liquids (inorganic, organic, metallic and salt) are introduced to verify this hypothesis. Good agreement from the theory prediction and experimental data can be obtained.

  8. Clinical analysis of molar fissures by Cone-beam tomography.

    Science.gov (United States)

    Cruvinel, V R N; Azevedo, B C; Gravina, D B L; Toledo, O A; Bezerra, A C B

    2007-01-01

    This study aimed to validate clinical analysis of 20 pediatric dentists on occlusal groove-fossa-system of molar depth comparing to Cone-beam tomography. The 48 sound third molars were visually classified from the shallowest to the deepest. Images were taken from the Accuitomo 3DX. There was a fair correlation between clinical analysis and the tomographic scorings (rs = 0.238; P = 0.103). It was concluded that pediatric dentists were not able to classify the fissures depth by visual analysis correctly. PMID:19161057

  9. TWO CANALS IN MAXILLARY FIRST MOLAR: A RARE DENTAL ENTITY

    Directory of Open Access Journals (Sweden)

    Dileep

    2016-01-01

    Full Text Available Root anatomy studies were divided into laboratory studies (In-Vitro, clinical root canal system anatomy studies (In vivo and clinical case reports of anomalies. Over 95% (95.9% of maxillary first molars had three roots and 3.9% had two roots. The incidence of fusion of any two or three roots was approximately 5.2%. Conical and C-shaped roots and canals were rarely found (0.12%.The fusion of the two buccal roots has the prevalence of 0.4% in maxillary first molars. Nevertheless, presence of only one buccal root with one canal is extremely rare.

  10. Effects of the Optimised pH and Molar Ratio on Struvite Precipitation in Aqueous System

    Directory of Open Access Journals (Sweden)

    Edahwati Luluk

    2016-01-01

    Full Text Available Struvite (MgNH4PO4.6H2O is one of phosphate minerals, commonly forms into aqueous solutions. It can be precipitated as mineral deposits for optimization of phosphate recovery based on the pH optimum, molar ratio and temperature levels. This paper presents results of a study on the struvite precipitation under the influence of pH variation, at optimized molar ratio and temperature, which were calculated from an experimental design methodology. Based on the methodology, a laboratory prepared struvite, made by mixing solutions to NH4OH, MgCl2 and H3PO4 for a molar ratio of 1: 2: 1 in a 500 mL volume of batch stirred crystallizer at room temperature. The crystallization was done at 200 rpm and the pH variation was adjusted to 8, 9 and 10 with KOH for a time of 70 minutes. The resulting crystals were filtered and dried at room temperature for 48 h and subsequently stored for further analysis. Material characterisasion of the crystals was conducted using XRPD Rietveld method of mineralogical composition. SEM equipped by EDX was employed for investigation of morphology and elemental composition of the crystals obtained. During the experiment, struvite crystals were firstly nucleated and subsequently developed at major value. The increase in pH is assumed to convert some of the struvite phase into struvite (K and minor sylvite (KCl. It demonstrates that Visual MINTEQ can be employed to estimate the mineral formation out the synthetic solutions.

  11. Mechanics of Apparent Horizon in Two Dimensional Dilaton Gravity

    CERN Document Server

    Cai, Rong-Gen

    2016-01-01

    In this article, we give a definition of apparent horizon in a two dimensional general dilaton gravity theory. With this definition, we construct the mechanics of the apparent horizon by introducing a quasi-local energy of the theory. Our discussion generalizes the apparent horizons mechanics in general spherically symmetric spactimes in four or higher dimensions to the two dimensional dilaton gravity case.

  12. Restauraciones cerámicas en molares jóvenes con endodoncia Ceramics restorations in young molars with endodontic

    Directory of Open Access Journals (Sweden)

    M. Urdaneta Quintero

    2009-12-01

    Full Text Available Objetivo: Efectuar restauraciones cerámicas Cerec (feldespática y de dióxido de circonio en molares jóvenes con endodoncia, para prevenir complicaciones en el aparato estomatognático por la pérdida de estos dientes. Material y métodos: Se describe la confección de restauraciones cerámicas a nivel de la zona molar mandibular derecha de un paciente del género femenino de 18 años de edad, a quien se le realizó radiografía periapical, por presentar dolor espontáneo en el lado derecho mandibular. Se diagnosticó una pulpitis irreversible en el primer y segundo molar que fue tratada endodónticamente. Las restauraciones cerámicas de ambos molares fueron confeccionadas con los sistemas CAD/CAM Cerec y evaluadas clínicamente a los 6 y 12 meses, de acuerdo a los criterios establecidos por el Servicio de Salud Pública de los Estados Unidos (USPHS. Resultados: La evaluación clínica evidenció que las estructuras de cerámica feldespática y de dióxido de circonio ofrecen en el lapso evaluado, adecuada forma anatómica, adaptación marginal, estabilidad en el color, ausencia de caries recidiva a nivel de dientes del sector posterior con tratamiento endodóntico y aceptación del paciente.Purpose: Make a ceramic restoration (feldsphatic and zirconium dioxide in young molars with endodontic treatment, to prevent further complications in the stomatognathic apparatus for the loss of these teeth. Material and methods: It describes the making of ceramic restorations in the right mandibular molar area to a female patient of 18 years old, to whom it was made a periapical radiography, for presenting spontaneous pain on the mandibular right side. It was diagnosed as an irreversible pulpitis at the first and second molar, that were treated endodontically. The ceramic restorations of both molars were made with the Cerec CAD/CAM system and were examined after 6 and 12 months in accordance with the US Public Health Service (USPHS criteria at baseline

  13. Una rara complicación en la extracción del tercer molar inferior incluido: Caso clínico A rare complication during the extraction of the included inferior third molar: Case report

    Directory of Open Access Journals (Sweden)

    S. Aboul-Hosn Centenero

    2009-10-01

    Full Text Available Presentamos una rara complicación ocurrida tras el intento de extracción del tercer molar incluido en una consulta odontológica bajo anestesia local. El paciente requirió ingreso en el servicio de urgencias para la extracción, de forma urgente, de la pieza a través de un abordaje cervical bajo anestesia general e intubación nasaotraqueal por desplazamiento de la pieza hacia la fosa submandibular durante el intento de extracción ambulatoria. El paciente presentó signos evidentes de inflamación en la región submandibular con desplazamiento de la vía aérea hacia el lado opuesto. Las complicaciones derivadas de la cirugía del tercer molar son, en algunos casos, mortales y pueden aparecer tras un acto quirúrgico aparentemente de bajo riesgo. Estas complicaciones han sido ampliamente descritas en la literatura. Aún así consideramos importante el presentar complicaciones poco frecuentes en la cirugía del tercer molar ya que esto nos permitirá conocerlas y ofrecer la mejor solución en cada caso.We present a rare complication that appeared after an attempt to extract the included third molar with local anaesthesia at the odontologist office. The patient was admitted to the emergency room to have the tooth removed cervically under general anaesthesia and nasotracheal tubation because of its movement towards the submandibular fossa during the ambulatory extraction attempt. The patient showed evident signs of swelling in submandibular region and the airway was displaced towards the opposite side. The resulting complications from the third molar surgery are, in some cases, mortal and can occur after an apparently low risk surgery. These complications have been thoroughly described in literature. Still, we consider it important to describe infrequent complications of third molar surgery because it will allow us to know more about them and offer the best solution in every case.

  14. Discrimination of paediatric brain tumours using apparent diffusion coefficient histograms

    Energy Technology Data Exchange (ETDEWEB)

    Bull, Jonathan G.; Clark, Christopher A. [UCL Institute of Child Health, Imaging and Biophysics Unit, London (United Kingdom); Saunders, Dawn E. [Great Ormond Street Hospital for Children NHS Trust, Department of Radiology, London (United Kingdom)

    2012-02-15

    To determine if histograms of apparent diffusion coefficients (ADC) can be used to differentiate paediatric brain tumours. Imaging of histologically confirmed tumours with pre-operative ADC maps were reviewed (54 cases, 32 male, mean age 6.1 years; range 0.1-15.8 years) comprising 6 groups. Whole tumour ADC histograms were calculated; normalised for volume. Stepwise logistic regression analysis was used to differentiate tumour types using histogram metrics, initially for all groups and then for specific subsets. All 6 groups (5 dysembryoplastic neuroectodermal tumours, 22 primitive neuroectodermal tumours (PNET), 5 ependymomas, 7 choroid plexus papillomas, 4 atypical teratoid rhabdoid tumours (ATRT) and 9 juvenile pilocytic astrocytomas (JPA)) were compared. 74% (40/54) were correctly classified using logistic regression of ADC histogram parameters. In the analysis of posterior fossa tumours, 80% of ependymomas, 100% of astrocytomas and 94% of PNET-medulloblastoma were classified correctly. All PNETs were discriminated from ATRTs (22 PNET and 4 supratentorial ATRTs) (100%). ADC histograms are useful in differentiating paediatric brain tumours, in particular, the common posterior fossa tumours of childhood. PNETs were differentiated from supratentorial ATRTs, in all cases, which has important implications in terms of clinical management. (orig.)

  15. Intrusion of overerupted molars by corticotomy and magnets.

    Science.gov (United States)

    Hwang, H S; Lee, K H

    2001-08-01

    Although posterior tooth intrusion in an adult patient is a difficult procedure, it can be achieved without extruding the adjacent teeth by performing a corticotomy and using magnets. In carrying out this procedure on 2 adult patients whose molars had overerupted due to the early loss of antagonists, tooth movement was rapidly achieved without discomfort or side effects. PMID:11500664

  16. Lower molar and incisor displacement associated with mandibular remodeling.

    Science.gov (United States)

    Baumrind, S; Bravo, L A; Ben-Bassat, Y; Curry, S; Korn, E L

    1997-01-01

    The purpose of this study was to quantify the amount of alveolar modeling at the apices of the mandibular incisor and first molar specifically associated with appositional and resorptive changes on the lower border of the mandible during growth and treatment. Cephalometric data from superimpositions on anterior cranial base, mandibular implants of the Björk type, and anatomical "best fit" of mandibular border structures were integrated using a recently developed strategy, which is described. Data were available at annual intervals between 8.5 and 15.5 years for a previously described sample of approximately 30 children with implants. The average magnitudes of the changes at the root apices of the mandibular first molar and central incisor associated with modeling/remodeling of the mandibular border and symphysis were unexpectedly small. At the molar apex, mean values approximated zero in both anteroposterior and vertical directions. At the incisor apex, mean values approximated zero in the anteroposterior direction and averaged less than 0.15 mm/year in the vertical direction. Standard deviations were roughly equal for the molar and the incisor in both the anteroposterior and vertical directions. Dental displacement associated with surface modeling plays a smaller role in final tooth position in the mandible than in the maxilla. It may also be reasonably inferred that anatomical best-fit superimpositions made in the absence of implants give a more complete picture of hard tissue turnover in the mandible than they do in the maxilla.

  17. Coronectomy may be a way of managing impacted third molars

    NARCIS (Netherlands)

    Ghaeminia, H.

    2013-01-01

    Data sourcesTPubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL) and the grey literature database SIGLE.Study selectionRandomised controlled trials (RCTs) and non-randomised controlled trials (CCTs) that compared coronectomy with total removal for third molar ext

  18. Standard molar enthalpies of formation of 1- and 2-cyanonaphthalene

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro da Silva, Manuel A.V., E-mail: risilva@fc.up.pt [Centro de Investigacao em Quimica, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Lobo Ferreira, Ana I.M.C.; Barros, Ana L.M.; Bessa, Ana R.C.; Brito, Barbara C.S.A.; Vieira, Joana A.S.; Martins, Silvia A.P. [Centro de Investigacao em Quimica, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)

    2011-09-15

    Highlights: > Enthalpies of formation of 1- and 2-cyanonaphthalene were measured by combustion calorimetry. > Vapor pressures of crystalline 1- and 2-cyanonaphthalene obtained by Knudsen effusion mass loss technique. > Enthalpies, entropies and Gibbs functions of sublimation at T = 298.15 K were calculated. - Abstract: The standard (p{sup o} = 0.1 MPa) molar enthalpies of formation, in the crystalline state, of the 1- and 2-cyanonaphthalene were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static-bomb combustion calorimetry. Vapor pressure measurements at different temperatures, using the Knudsen mass loss effusion technique, enabled the determination of the enthalpy, entropy, and Gibbs energy of sublimation, at T = 298.15 K, for both isomers. The standard molar enthalpies of sublimation, at T = 298.15 K, for 1- and 2-cyanonaphthalene, were also measured by high-temperature Calvet microcalorimetry. (table) Combining these two experimental values, the gas-phase standard molar enthalpies, at T = 298.15 K, were derived and compared with those estimated by employing two different methodologies: one based on the Cox scheme and the other one based on G3MP2B3 calculations. The calculated values show a good agreement with the experimental values obtained in this work.

  19. Experimental standard molar enthalpies of formation of some methylbenzenediol isomers

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro da Silva, Manuel A.V. [Centro de Investigacao em Quimica, Department of Chemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P 4169-007 (Portugal)], E-mail: risilva@fc.up.pt; Lobo Ferreira, Ana I.M.C. [Centro de Investigacao em Quimica, Department of Chemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P 4169-007 (Portugal)

    2009-10-15

    The present work is part of a research program on the energetics of formation of alkyl substituted benzenediols, aiming the study of the enthalpic effect of the introduction of methyl substituents into benzenediols. In this work we present the results of the thermochemical research on 2-methylresorcinol, 3-methylresorcinol, 4-methylresorcinol, and methylhydroquinone. The standard (p{sup 0}=0.1MPa) molar enthalpies of formation, in the crystalline phase, at T = 298.15 K, of the compounds mentioned above were derived from their standard massic energies of combustion, measured by static-bomb combustion calorimetry, while the standard molar enthalpies of sublimation of those compounds were obtained by the temperature dependence of their vapour pressures determined by the Knudsen effusion technique. From experimental values, the standard molar enthalpies of formation of the studied methylbenzenediols in the gaseous phase, at T = 298.15 K were then derived. The results are interpreted in terms of structural contributions to the energetics of the substituted benzenediols and compared with the same parameters estimated from the Cox Scheme. Moreover, the standard (p{sup 0}=0.1MPa) molar enthalpies, entropies, and Gibbs energies of sublimation, at T = 298.15 K, were derived for the four isomers of methylbenzenediols.

  20. Miniscrew-supported coil spring for molar uprighting: description

    Directory of Open Access Journals (Sweden)

    Antônio Carlos de Oliveira Ruellas

    2013-02-01

    Full Text Available INTRODUCTION: Since the beginning of miniscrews as orthodontic anchorage, many applications have been described in the literature. Among these, one is the uprighting of mesially inclined molars. In regard to the mechanical aspects, however, there is little information about the application of orthodontic forces using such devices. OBJECTIVE: The objective of this study was to describe a miniscrew supported spring for uprighting of mesially inclined molars. With this device, one can achieve the correct use of orthodontic biomechanics, thus favoring more predictable tooth movements and preventing unwanted movements from occurring.INTRODUÇÃO: desde o surgimento dos mini-implantes como recurso de ancoragem ortodôntica, muitas aplicações têm sido descritas na literatura. Entre essas, cita-se a verticalização de molares inclinados para mesial. No entanto, pouco se fala da correta aplicação das forças ortodônticas nesses dispositivos, sob o ponto de vista mecânico. OBJETIVOS: o objetivo desse artigo foi demonstrar uma mola mini-implante suportada para verticalizar molares inclinados para mesial. Com esse dispositivo consegue-se correta aplicação da mecânica ortodôntica, favorecendo movimentos mais previsíveis e minimizando os movimentos indesejáveis.

  1. Non-compliance Appliances for Upper Molar Distalization: An Overview.

    Science.gov (United States)

    Noorollahian, Saeed; Alavi, Shiva; Shirban, Farinaz

    2015-01-01

    Tooth Size Arch-length Discrepancy (TSALD) is a common problem in orthodontics. Its clinical signs are tooth crowding, impaction and incisor proclination. The treatment options are dental arch expansion or tooth mass reduction (stripping or extraction). The "extraction versus non-extraction" controversy has been widely debated in the orthodontic literature. Distalization is a kind of arch expansion in anetro-posterior dimension. Several studies have evaluated both the therapeutic effectiveness and the side effects of the appliances for this method of space gaining. In some cases molar distalization is preferred, e.g., a patient with acceptable profile and skeletal pattern and half cusp Class II molar malocclusion or even less. In some cases molar distalization is the only way, e.g., the patient with previous upper premolar extraction and excessive overijet, or a skeletal Class III patient with previous upper premolar extraction needed upper anterior teeth retraction to create reverse overjet aspre surgical orthodontic decompensation. In this review article, we described non-compliance upper molar distalizing appliances. PMID:26720949

  2. The chronology of third molar mineralization by digital orthopantomography.

    Science.gov (United States)

    Maled, Venkatesh; Vishwanath, S B

    2016-10-01

    The present study was designed to determine the chronology of third molar mineralization to establish Indian reference data and to observe the advantages of digital orthopantomography. Therefore, a cross-sectional study was undertaken by evaluating 167 digital orthopantomographs in order to assess the mineralization status of the mandibular third molar of Caucasian individuals (85 males and 82 females) between the age of 14 and 24. The evaluation was carried out using the 8-stage developmental scheme of Demirjian et al (1973). The range, mean age, standard deviation and Student t-test are presented for each stage of mineralization in all four quadrants. Statistically significant differences between males and females were not found for all four third molars. All the individuals in this study with mature third molar were at least 18 years of age. For medicolegal purposes, the likelihood of whether an Indian is older than 18 years or not was determined. The advantage of digital orthopantomography in the interpretation of the tooth mineralization over the traditional method was acknowledged. PMID:27485643

  3. The chronology of third molar mineralization by digital orthopantomography.

    Science.gov (United States)

    Maled, Venkatesh; Vishwanath, S B

    2016-10-01

    The present study was designed to determine the chronology of third molar mineralization to establish Indian reference data and to observe the advantages of digital orthopantomography. Therefore, a cross-sectional study was undertaken by evaluating 167 digital orthopantomographs in order to assess the mineralization status of the mandibular third molar of Caucasian individuals (85 males and 82 females) between the age of 14 and 24. The evaluation was carried out using the 8-stage developmental scheme of Demirjian et al (1973). The range, mean age, standard deviation and Student t-test are presented for each stage of mineralization in all four quadrants. Statistically significant differences between males and females were not found for all four third molars. All the individuals in this study with mature third molar were at least 18 years of age. For medicolegal purposes, the likelihood of whether an Indian is older than 18 years or not was determined. The advantage of digital orthopantomography in the interpretation of the tooth mineralization over the traditional method was acknowledged.

  4. Molar Intubation for Intra Oral Swellings:Our Experience

    Directory of Open Access Journals (Sweden)

    Meenoti Potdar

    2008-01-01

    Full Text Available Molar intubation is a technique of laryngoscopy that can be used for anticipated difficult intubation in cases where standard laryngoscopy technique is difficult due to presence of any intraoral mass that anatomically hampers laryngoscopy or that bleeds on touch. This technique is very easy, reliable and rewarding but should be practiced on normal patients for easy application in actual difficult cases.

  5. A cervical ectopic masquerading as a molar pregnancy.

    Science.gov (United States)

    Masir, N; Tamby, M R; Jamil, M A

    2000-03-01

    We report a case of cervical pregnancy complicated by life threatening hemorrhage. An initial diagnosis of molar pregnancy was made preoperatively. During uterine evacuation she developed profuse hemorrhage which required an emergency hysterectomy for uncontrolled bleeding. Histopathological examination confirmed a cervical pregnancy. The clinical and pathological criteria for the diagnosis and the etiology of cervical pregnancy are discussed. PMID:11072500

  6. Internal structure of mandible around mandibular molar using computed tomography. Anatomical consideration of molar anchorage in orthodontic treatment

    International Nuclear Information System (INIS)

    For establishment of fine occlusion, facial profile and oral function in orthodontic treatment, molar anchorage in teeth movement is important manner in extracted cases. The aims of this study were to investigate the relationship between facial morphology and internal structure of mandibular body in molar region by computer tomography, and to discuss about molar anchorage in orthodontic treatment. The data for this study were obtained from 35 modern male Japanese skulls (mean age; 27 year-old, ranged from 18 year-old to 47 year-old). Measurement variables were FMA, SN to mandibular plane angle, gonial angle, alveolar breadth, cortical bone thickness of buccal and lingual sides, and the distance between dental root and cortical bone. As a result, alveolar breadth and the distance between dental root and cortical bone were narrow in long facial type, on the contrary, these variables were wide in short facial type. The result suggested that these variables were considered important factors as molar anchorage in extracted cases. (author)

  7. Gas Phase Pressure Effects on the Apparent Thermal Conductivity of JSC-1A Lunar Regolith Simulant

    Science.gov (United States)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    Gas phase pressure effects on the apparent thermal conductivity of a JSC-1A/air mixture have been experimentally investigated under steady state thermal conditions from 10 kPa to 100 kPa. The result showed that apparent thermal conductivity of the JSC-1A/air mixture decreased when pressure was lowered to 80 kPa. At 10 kPa, the conductivity decreased to 0.145 W/m/degree C, which is significantly lower than 0.196 W/m/degree C at 100 kPa. This finding is consistent with the results of previous researchers. The reduction of the apparent thermal conductivity at low pressures is ascribed to the Knudsen effect. Since the characteristic length of the void space in bulk JSC-1A varies over a wide range, both the Knudsen regime and continuum regime can coexist in the pore space. The volume ratio of the two regimes varies with pressure. Thus, as gas pressure decreases, the gas volume controlled by Knudsen regime increases. Under Knudsen regime the resistance to the heat flow is higher than that in the continuum regime, resulting in the observed pressure dependency of the apparent thermal conductivity.

  8. Predicting the apparent viscosity and yield stress of digested and secondary sludge mixtures.

    Science.gov (United States)

    Eshtiaghi, Nicky; Markis, Flora; Zain, Dwen; Mai, Kiet Hung

    2016-05-15

    The legal banning of conventional sludge disposal methods such as landfill has led to a global movement towards achieving a sustainable sludge management strategy. Reusing sludge for energy production (biogas production) through the anaerobic digestion of sludge can provide a sustainable solution. However, for the optimum performance of digesters with minimal use of energy input, operating conditions must be regulated in accordance with the rheological characteristics of the sludge. If it is assumed that only secondary sludge enters the anaerobic digesters, an impact of variations to the solids concentration and volume fraction of each sludge type must be investigated to understand how the apparent viscosity and yield stress of the secondary and digested sludge mixture inside the digesters changes. In this study, five different total solids concentration of secondary and digested sludge were mixed at different digested sludge volume fractions ranging from 0 to 1. It was found that if secondary sludge was mixed with digested sludge at the same total solids concentration, the apparent viscosity and the yield stress of the mixture increased exponentially by increasing the volume fraction of digested sludge. However, if secondary sludge was added to digested sludge with a different solids concentration, the apparent viscosity and yield stress of the resulting mixed sludge was controlled by the concentrated sludge regardless of its type. Semi - empirical correlations were proposed to predict the apparent viscosity and yield stress of the mixed digested and secondary sludge. A master curve was also developed to predict the flow behaviour of sludge mixtures regardless of the total solid concentration and volume fraction of each sludge type within the studied solids concentration range of 1.4 and 7%TS. This model can be used for digesters optimization and design by predicting the rheology of sludge mixture inside digester. PMID:26994336

  9. Corticotomy-assisted molar protraction with the aid of temporary anchorage device.

    Science.gov (United States)

    Uribe, Flavio; Janakiraman, Nandakumar; Fattal, Amine N; Schincaglia, Gian Pietro; Nanda, Ravindra

    2013-11-01

    This case report describes the interdisciplinary management of a 58-year-old woman who was missing lower first molars and supraerupted maxillary first molars. The treatment plan included intrusion of the upper first molars and corticotomy-assisted mandibular second molar protraction with the aid of temporary anchorage devices. Miniscrews were effective in intrusion of the maxillary first molars and protraction of the lower second molars. Although good functional outcome was achieved in 41 months, the corticotomy-assisted procedure did not significantly reduce the treatment time. PMID:23834274

  10. Size dependence of cavity volume: a molecular dynamics study.

    Science.gov (United States)

    Patel, Nisha; Dubins, David N; Pomès, Régis; Chalikian, Tigran V

    2012-02-01

    Partial molar volume, V°, has been used as a tool to sample solute hydration for decades. The efficacy of volumetric investigations of hydration depends on our ability to reliably discriminate between the cavity, V(C), and interaction, V(I), contributions to the partial molar volume. The cavity volume, V(C), consists of the intrinsic volume, V(M), of a solute molecule and the thermal volume, V(T), with the latter representing the volume of the effective void created around the solute. In this work, we use molecular dynamics simulations in conjunction with the Kirkwood-Buff theory to compute the partial molar volumes for organic solutes of varying sizes in water. We perform our computations using the Lennard-Jones and Coulombic pair potentials as well as truncated potentials which contain only the Lennard-Jones but not the Coulombic contribution. The partial molar volume computed with the Lennard-Jones potentials in the absence of the Coulombic term nearly coincides with the cavity volume, V(C). We determine the thermal volume, V(T), for each compound by subtracting its van der Waals volume, V(W), from V(C). Finally, we apply the spherical approximation of solute geometry to evaluate the thickness of the thermal volume, δ. Our results reveal an increase in the thickness of thermal volume, δ, with an increase in the size of the solute. This finding may be related to dewetting of large nonpolar solutes and the concomitant increase in the compressibility of water of hydration. PMID:22133917

  11. Space loss following premature loss of primary second molars.

    Science.gov (United States)

    Alnahwi, Hassan H; Donly, Kevin J; Contreras, Claudia I

    2015-01-01

    This study was designed to evaluate the amount of space loss (SL) caused by premature loss of primary second molars, determine whether the eruption status of permanent first molars is an important factor in the amount of SL, and evaluate the effectiveness of space maintainers (SMs) in SL prevention. SL associated with 100 prematurely extracted primary second molars was evaluated in 87 healthy patients. Teeth were divided into groups based on the use of SMs (36 with SM and 64 without SM). Bitewing and periapical radiographs taken before extraction and 6, 12, 24, 36, and 48 months after extraction were used to determine the amount of SL. Not every patient attended every recall appointment, so the sample size varied at different evaluation times. The most significant amount of SL occurred in the first 12 months after extraction. In patients who did not use an SM, at 6 months there was a mean SL of 2.12 mm (SD, 1.65 mm) and at 12 months there was a mean of 4.02 mm (SD, 1.65), with significantly more SL in the first 6 months (P 0.05). When patients without an SM were grouped by the eruption status of the permanent first molar, there was significantly more SL in the groups with unerupted first molars than there was in the groups with erupted first molars at both 6 months (P < 0.001) and 12 months (P < 0.05). At both 6 and 12 months, the amount of SL in patients who had an SM (n = 13 and n = 14, respectively) was not significantly different from the amount of SL in those who did not have an SM (n = 33 and n = 23, respectively). SMs should be placed as soon as possible following tooth extraction to prevent undue SL. Placement of an SM a year or more after extraction has minimal benefit, since most SL takes place within the first year. SL does occur even when SMs are used.

  12. Thermodynamic Behavior of Friedmann Equations at Apparent Horizon of FRW Universe

    CERN Document Server

    Akbar, M; Cai, Rong-Gen

    2006-01-01

    It is shown that the differential form of Friedmann equations of a FRW universe can be rewritten as a thermodynamical identity $TdS = dE + PdV$ at apparent horizon, where $E$ is the Misner-Sharp energy, $V$ is the volume inside the apparent horizon, and $P$ is the pressure of the perfect fluid in the universe. From the thermodynamic identity one can derive that the apparent horizon $\\tilde r_A$ has associated temperature $T=1/2\\pi \\tilde r_A$ and entropy $S= A/4G$ in Einstein general relativity, where $A$ is the area of apparent horizon. We extend our procedure to the Gauss-Bonnet gravity and more general Lovelock gravity and show that the field equations in these gravities can also be identified as a thermodynamical system satisfying $TdS = dE + PdV$ at the apparent horizon of FRW universe with entropy $S$ being given by expression previously known via black hole thermodynamics.

  13. Exploring metameric variation in human molars: a morphological study using morphometric mapping.

    Science.gov (United States)

    Morita, Wataru; Morimoto, Naoki; Ohshima, Hayato

    2016-09-01

    Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to explain how this variation is brought about in the molars. Actualistic data that support the theories, however, are still relatively scarce because of methodological limitations. Here we propose new methods to analyse detailed tooth crown morphologies. We applied morphometric mapping to the enamel-dentine junction of human maxillary molars and examined whether odontogenetic models were adaptable to human maxillary molars. Our results showed that the upper first molar is phenotypically distinct among the maxillary molars. The average shape of the upper first molar is characterized by four well-defined cusps and precipitous surface relief of the occlusal table. On the other hand, upper third molar is characterized by smooth surface relief of the occlusal table and shows greater shape variation and distinct distribution patterns in morphospace. The upper second molar represents an intermediate state between first and third molar. Size-related shape variation was investigated by the allometric vector analysis, and it appeared that human maxillary molars tend to converge toward the shape of the upper first molar as the size increases. Differences between the upper first molar and the upper second and third molar can thus be largely explained as an effect of allometry. Collectively, these results indicate that the observed pattern of metameric variation in human molars is consistent with odontogenetic models of molar row structure (inhibitory cascade model) and molar crown morphology (patterning cascade model). This study shows that morphometric mapping is a useful tool to visualize and quantify the morphological features of teeth, which can provide the basis for a better understanding of tooth evolution linking morphology and development. PMID:27098351

  14. [The relation of pericoronitis to the position of the mandibular third molar].

    Science.gov (United States)

    Lee, D K; Kim, B J

    1989-02-01

    Pericoronitis is the most commonly encountered pathologic condition involving the mandibular third molar. Because of the dangers associated with mandibular third molar pericoronitis, prophylactic extraction of third molar at high risk has been recommended. We studied 411 patients with mandibular third molar pericoronitis by clinical symptoms and radiographic measurement of mandibular third molar height, wideth and angulation. The results were as follows: 1. Mandibular third molar pericoronitis is frequently seen in third decade and there are no sexual difference significantely. 2. In inflammatory type of mandibular third molar pericoronitis, chronic pericoronitis occured more frequently than acute type. 3. In relation to angulation and height, mandibular third molar most likely to be afflicted with pericoronitis is vertical eruption at occlusal plane of the second molar. 4. In relation to angulation and width, it appears that the position of the mandibular third molar most likely to be afflicted with pericoronitis is in a vertically erupted tooth of which the space between the ramus and the distal side of the second molar is less than the mesiodistal diameter of crown. (Class II). 5. In relation to height and width, it appears that the position of the mandibular third molar most likely to be afflicted with pericoronitis is class II width (described above)at occlusal plane of the second molar.

  15. Removal of trace Cd2+ using continuous multistage ion foam fractionation: Part I-The effect of feed SDS/Cd molar ratio

    International Nuclear Information System (INIS)

    In this research, a continuous multistage ion foam fractionation column with bubble-cap trays was employed to remove cadmium ions from simulated wastewater having cadmium ions at a low level (10 mg/L). In this study, sodium dodecyl sulfate (SDS) was used to generate the foam. An increase in feed SDS/Cd molar ratio enhanced the removal of Cd. However, the SDS concentration above a certain level resulted in wetter foams, leading to having a high volume of generated foam that lowered both the enrichment ratio and separation factor of the Cd. The SDS recovery tended to increase with increasing feed SDS/Cd molar ratio. The molar ratio of SDS/Cd in foamate was found to be close to the theoretical adsorption molar ratio of 2/1 on the air-water interface of foam when the system was operated at a feed SDS/Cd molar ratio in the range of 2/1-7/1. Ion foam fractionation has been demonstrated in this study to be a promising technique for high heavy metal removal (more than 99%) for a feed having a low heavy metal concentration in the ppm (mg/L) level.

  16. Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C211H17NO(s)

    Institute of Scientific and Technical Information of China (English)

    Di You-Ying; Wang Da-Qi; Shi Quan; Tan Zhi-Cheng

    2008-01-01

    This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO(s) have been mea- sured by a precision automated adiabatic calorimeter over the temperature range from T=78 K to T=400 K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342- 364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO(s) relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol preci- sion oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

  17. Predicting the apparent viscosity and yield stress of mixtures of primary, secondary and anaerobically digested sewage sludge: Simulating anaerobic digesters.

    Science.gov (United States)

    Markis, Flora; Baudez, Jean-Christophe; Parthasarathy, Rajarathinam; Slatter, Paul; Eshtiaghi, Nicky

    2016-09-01

    Predicting the flow behaviour, most notably, the apparent viscosity and yield stress of sludge mixtures inside the anaerobic digester is essential because it helps optimize the mixing system in digesters. This paper investigates the rheology of sludge mixtures as a function of digested sludge volume fraction. Sludge mixtures exhibited non-Newtonian, shear thinning, yield stress behaviour. The apparent viscosity and yield stress of sludge mixtures prepared at the same total solids concentration was influenced by the interactions within the digested sludge and increased with the volume fraction of digested sludge - highlighted using shear compliance and shear modulus of sludge mixtures. However, when a thickened primary - secondary sludge mixture was mixed with dilute digested sludge, the apparent viscosity and yield stress decreased with increasing the volume fraction of digested sludge. This was caused by the dilution effect leading to a reduction in the hydrodynamic and non-hydrodynamic interactions when dilute digested sludge was added. Correlations were developed to predict the apparent viscosity and yield stress of the mixtures as a function of the digested sludge volume fraction and total solids concentration of the mixtures. The parameters of correlations can be estimated using pH of sludge. The shear and complex modulus were also modelled and they followed an exponential relationship with increasing digested sludge volume fraction. PMID:27243386

  18. Molar distalization with the assistance of Temporary Anchorage Devices.

    Science.gov (United States)

    Palencar, Adrian J

    2015-01-01

    This article describes efficient techniques for distalization of maxillary and mandibular molars with the assistance of Temporary Anchorage Devices (TADs). There are numerous occasions where the distalization of molars is required in lieu of the odontectomy of bicuspids. In the past, extra-oral force has been used, (i.e. Cervical or Combination Head Gear, or intra-oral force, i.e. Posterior Sagittal Appliance, Modified Greenfield Appliance, Williams DMJ 20001, CD Distalizer, Magill Sagittal, Pendulum Appliance, etc.). All the intra-oral appliances have a common denominator the orthodontic clinician has to deal with, the undesirable expression of the Third Law of Newton. The utilization of TADs allows us to circumvent this shortcoming, establishing an absolute anchorage, and thus completely negate the expression of the Third Law of Newton. PMID:25881377

  19. Ectopic 3rd Molar Tooth in the Maxillary Antrum

    Directory of Open Access Journals (Sweden)

    Seidu A. Bello

    2014-01-01

    Full Text Available Location of ectopic tooth in a nondentate area like the maxillary antrum is rare. A 17-year-old boy, with one year history of recurrent right facial swelling and radiographic finding of a maxillary third molar tooth located at the posterior wall of the maxillary antrum, is presented. Under endotracheal intubation, the tooth was extracted through a Caldwell-Luc antrostomy approach and patient had an uneventful recovery and has been symptom free for eight months. Ectopic tooth in the maxillary antrum is rare and is commonest with maxillary third molar. It may be symptomless but is more commonly associated with inflammatory symptoms. The treatment of choice is surgical excision which is mostly carried out with Caldwell-Luc approach, even though endoscopic approach is being reported.

  20. Periodontal pathogens in erupting third molars of periodontally healthy subjects.

    Science.gov (United States)

    Rajasuo, A; Sihvonen, O J; Peltola, M; Meurman, J H

    2007-09-01

    The presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia and Tannerella forsythensis in bacteriologic samples of 5-7-mm deep mandibular third-molar pericoronal pockets was analysed by polymerase chain reaction, to test the hypothesis that these sites would harbour the bacteria. The patients were periodontally healthy 20-year-old Finnish male conscripts. Sixteen had acute pericoronitis, 28 chronic pericoronitis, and 15 were symptom-free controls. A. actinomycetemcomitans was detected in only 7% of the samples from chronic pericoronitis cases, whereas P. gingivalis was positive in 20% of the symptom-free versus 69% (P = 0.018) of the acute and 57% (P = 0.044) of the chronic cases. The percentages for P. intermedia were 93, 94 and 93%, and for T. forsythensis 47, 63 and 57%, respectively. These results confirm that, apart from A. actinomycetemcomitans, periodontopathogens are common in third-molar sites in periodontally healthy individuals.

  1. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans

    Science.gov (United States)

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (~2,500-750 million years ago, Ma) subtidal successions, but extremely rare in rocks dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end.

  2. Quasar Apparent Proper Motion Observed by Geodetic VLBI Networks

    OpenAIRE

    D. S. MacMillan

    2003-01-01

    In our standard geodetic VLBI solutions, we estimate the positions of quasars assuming that their positions do not vary in time. However, in solutions estimating proper motion, a significant number of quasars show apparent proper motion greater than 50 uas/yr. For individual quasars, there are source structure effects that cause apparent proper motion. To examine how coherent the pattern of apparent proper motion is over the sky, we have estimated the vector spherical harmonic components of t...

  3. Pendulum Therapy of Molar Distalization in Mixed Dentition

    OpenAIRE

    Patil, Raju Umaji; Prakash, Amit; Agarwal, Anshu

    2016-01-01

    ABSTRACT Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient’s compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a ...

  4. The Chronology of Third Molar Eruption in the Croatian Population

    OpenAIRE

    Brkić, Hrvoje; Vodanović, Marin; Dumančić, Jelena; Lovrić, Željka; Čuković-Bagić, Ivana; Petrovečki, Mladen

    2011-01-01

    Dental age estimation is common in orthodontics, paedodontics, paleodontology and forensic dentistry. The aim of this study was to assess chronological course of eruptive developmental phases of third molar and to establish parameters for the Croatian population. Sample of this study consisted of 1249 orthopantomograms of 530 (42.4%) male and 719 (57.6%) female subjects, aged 10 to 25 years. Eruptive phases were classified in 4 stages. No significant sex difference was found. Esta...

  5. A geometric morphometric analysis of hominin upper first molar shape

    OpenAIRE

    Gómez Robles, Aida; Martinón Torres, María; Bermúdez de Castro, José María; Margvelashvili, A.; Bastir, Markus; Arsuaga, Juan Luis; Pérez Pérez, Alejandro; Estebaranz, Ferran; Martínez, Laura M.

    2007-01-01

    Recent studies have revealed interesting differences in upper first molar morphology across the hominin fossil record, particularly significant between H. sapiens and H. neanderthalensis. Usually these analyses have been performed by means of classic morphometric methods, including the measurement of relative cusp areas or the angles defined between cusps. Although these studies have provided valuable information for the morphological characterization of some hominin species, we beli...

  6. Interfacial Properties of Methylcelluloses: The Influence of Molar Mass

    OpenAIRE

    Pauline L. Nasatto; Frédéric Pignon; Silveira, Joana L.M.; Maria Eugênia R. Duarte; Miguel D. Noseda; Marguerite Rinaudo

    2014-01-01

    The interfacial interactions of four methylcelluloses having the same average degree of substitution and distribution of methyl groups, but different molar masses, are studied at ambient temperature and at very low polymer concentrations. Firstly, the surface tension σ at the water/air interface is determined for the progressive addition of methylcellulose up to 100 mg/L; σ starts to decrease over 1 mg/L up to the critical aggregation concentration (CAC) at 10 mg/L. The curves describing the...

  7. First molar health status in different craniofacial relationships

    OpenAIRE

    Linjawi, Amal

    2016-01-01

    Amal I Linjawi Department of Orthodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia Objective: To investigate the association between the health status of permanent first molars and different craniofacial relationships among adolescents. Study design: This is a retrospective study on patients’ records aged 11–15 years. Sex, skeletal relationship, vertical growth pattern, malocclusion, overjet, and overbite were assessed. The health status of pe...

  8. Effective molarity in a nucleic acid-controlled reaction.

    Science.gov (United States)

    Catalano, Michael J; Price, Nathan E; Gates, Kent S

    2016-06-01

    Positioning of reactive functional groups within a DNA duplex can enable chemical reactions that otherwise would not occur to an appreciable extent. However, few studies have quantitatively defined the extent to which the enforced proximity of reaction partners in duplex DNA can favor chemical processes. Here, we measured substantial effective molarities (as high as 25M) afforded by duplex DNA to a reaction involving interstrand cross-link formation between 2'-deoxyadenosine and a 2-deoxyribose abasic (Ap) site. PMID:27117430

  9. Patterning by heritage in mouse molar row development

    OpenAIRE

    Prochazka, Jan; Pantalacci, Sophie; Churava, Svatava; Rothova, Michaela; Lambert, Anne; Lesot, Hervé; Klein, Ophir; Peterka, Miroslav; Laudet, Vincent; Peterkova, Renata

    2010-01-01

    It is known from paleontology studies that two premolars have been lost during mouse evolution. During mouse mandible development, two bud-like structures transiently form that may represent rudimentary precursors of the lost premolars. However, the interpretation of these structures and their significance for mouse molar development are highly controversial because of a lack of molecular data. Here, we searched for typical tooth signaling centers in these two bud-like structures, and followe...

  10. The third molar as an age marker in adolescents: new approach to age evaluation.

    Science.gov (United States)

    Rozkovcova, Eva; Dostalova, Tatjana; Markova, Marie; Broukal, Zdenek

    2012-09-01

    Adolescence is a relatively short period between childhood and adulthood. It is very difficult to determine adulthood based on biological indicators. The third molar may be considered a potential age marker for the period between the ages of 16-21. Our study evaluated a set of 1700 panoramic radiographs of individuals aged between 5 and 21 years. Results confirmed the statistically significant difference in the course of third molars development. The mean deviation for individuals with one third molar agenesis is -0.98 years, for individuals with two third molars agenesis -1.89 years, and with three molars agenesis -3.28 years. Thus, the extent of the deviation is directly proportional to the number of unformed third molars. The calculation of age according to the mean of stages of all third molars could lead to the underestimation of age. No intergender differences were found. Age determination using third molars could be used for forensic purposes.

  11. Spontaneous emergence of overgrown molar teeth in a colony of Prairie voles (Microtus ochrogaster)

    Institute of Scientific and Technical Information of China (English)

    Andrew H Jheon; Michaela Prochazkova; Michael Sherman; Devanand S Manoli; Nirao M Shah; Lawrence Carbone; Ophir Klein

    2015-01-01

    Continuously growing incisors are common to all rodents, which include the Microtus genus of voles. However, unlike many rodents, voles also possess continuously growing molars. Here, we report spontaneous molar defects in a population of Prairie voles (Microtus ochrogaster). We identified bilateral protuberances on the ventral surface of the mandible in several voles in our colony. In some cases, the protuberances broke through the cortical bone. The mandibular molars became exposed and infected, and the maxillary molars entered the cranial vault. Visualisation upon soft tissue removal and microcomputed tomography (microCT) analyses confirmed that the protuberances were caused by the overgrowth of the apical ends of the molar teeth. We speculate that the unrestricted growth of the molars was due to the misregulation of the molar dental stem cell niche. Further study of this molar phenotype may yield additional insight into stem cell regulation and the evolution and development of continuously growing teeth.

  12. Relationship of third molar movement during orthodontic treatment and root angulation

    Directory of Open Access Journals (Sweden)

    Morteza Oshagh

    2012-01-01

    Conclusion: The relation between the amount of third molar movement and its root angulation was not statistically significant. Therefore movement of third molars during orthodontic treatment should not be assumed as an etiologic factor of root angulations.

  13. The Use of Narrow Diameter Implants in the Molar Area

    Directory of Open Access Journals (Sweden)

    M. Saad

    2016-01-01

    Full Text Available Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence.

  14. The Use of Narrow Diameter Implants in the Molar Area.

    Science.gov (United States)

    Saad, M; Assaf, A; Gerges, E

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  15. Molar pregnancy with multiple organ dysfunction, an interesting

    Directory of Open Access Journals (Sweden)

    Purnima deb

    2011-01-01

    Full Text Available Successful management and cure of gestational trophoblastic disease [GTD, molar ] depends upon prompt, accurate diagnosis and institution of individualized, therapeutic modalities. Because Molar pregnancies encompasses multitude of clinical entities, each with myriad presentations, clinicians must remain alert to identify patients exhibiting signs and symptoms consistent with GTD [molar]. Armed with a high index of suspicion, physicians may target such individuals and launch the appropriate diagnostic barrage, leading to triage for treatment early in the course of the disease. The disease if not diagnosed early may lead to complication such as, acute respiratory distress, cardiac failure, liver and renal failure. Intracranial bleeding and seizures complicated with infection and coagulation failure may lead to death of these young women. Little data are available to assist in the counselling of women with diagnosis and compulsory follow up. Appropriate contraception should be discussed and advise given before discharge as they may get lost to follow up. These women should be informed of the elevated risk of developing malignant sequlae in future.

  16. Decontamination of tried-in orthodontic molar bands.

    Science.gov (United States)

    Fulford, M R; Ireland, A J; Main, B G

    2003-12-01

    Molar bands are commonly used to retain orthodontic attachments on posterior teeth and due to the variation in the size of such teeth, it is usually necessary to 'try in' several bands before the correct one is selected. A possible concern with re-using such bands is the lack of cross-infection control, even following autoclaving, due to the presence of one or more small bore lumen (the archwire and headgear tubes). The aim of this experiment was, therefore, to determine whether such bands could be successfully decontaminated so that they could be re-used without a cross-infection risk. Two hundred orthodontic molar bands that had previously been tried in patients' mouths, but not cemented into place, were tested. Each band was decontaminated using an enzymatic cleaner/disinfectant and then sterilized using either a downward displacement (n = 100) or a vacuum cycle autoclave (n = 100). Following autoclaving each band was inoculated into brain heart infusion culture broth and incubated at 37 degrees C for 5 days. None of the decontaminated bands exhibited growth after 5 days. It would appear that, using this methodology, there is little risk of a cross-infection hazard occurring with the re-use of previously tried-in and decontaminated molar bands.

  17. 3-D diagnosis-assisted management of anomalous mandibular molar

    Directory of Open Access Journals (Sweden)

    Neelam Mittal

    2012-01-01

    Full Text Available This case report describes the successful non-surgical endodontic management of carious exposed three-rooted mandibular molar with four root canals detected on the pre-operative radiograph taken with 20 degrees mesial angulation and confirmed with a 64-slice helical computed tomography scan-assisted 3-D-reconstructed images. Access cavity shape was modified to locate the extra canal with respect to the distolingual root in the left mandibular first molar. Copious irrigation was accomplished with 5.25% sodium hypochlorite and 17% EDTA. Biomechanical preparation was done using protapers. Calcium hydroxide dressing was done for 1 week. The tooth was obturated using gutta percha and AH 26 root canal sealer, and it was permanently restored with composite. Clinical examination on follow-up visits revealed no sensitivity to percussion and palpation in the left mandibular first molar. Thorough knowledge of root canal variations and use of advanced diagnostic modalities lead to successful non-surgical management of the complex cases.

  18. Variable permanent mandibular first molar: Review of literature

    Science.gov (United States)

    Ballullaya, Srinidhi V; Vemuri, Sayesh; Kumar, Pabbati Ravi

    2013-01-01

    Introduction: The success of root canal therapy depends on the locations of all the canals, thourough debridement and proper sealing. At times the clinicians are challenged with variations in morphology of root canal. This review article attempts to list out all the variations of permanent mandibular first molar published so for in the literature. Materials and Methods: An exhaustive search was undertaken using PUBMED database to identify published literature from 1900 to 2010 relating to the root canal morphology of permanent first molar by using key words. The selected artcles were obtained and reviewed. Results: Total ninty seven articles were selected out of which 50 were original article and forty seven were case reports. The incidence of third canal in mesial root was 0.95% to 15%. The incidence of three rooted mandibular first molar was 3% to 33%. Only ninety cases reported with c-shape canal configuration. Incidence of Taurodintism without congenital disorder was very rare. Conclusion: The root canal treatment requires proper knowlegde of variations in root canal morphology in order to recognise, disinfect and seal all portal of exit. This can be accomplished with proper diagnosis using newer modes, modification in access preparation, use of operating microscope, enhanced methods of disinfecting and sealing of all canals. PMID:23716959

  19. Evaluation of periodontal condition in intruded molars using miniscrews

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    Habib Ollah Ghanbari

    2015-12-01

    Full Text Available Introduction: The purpose of this preliminary study was to evaluate the periodontal condition of intruded molars in various phases of treatments. Methods: 30 patients with at least one overerupted upper first molar were selected. Upper molar bands with brackets were cemented. Two miniscrews were placed in the mesiopalatal and mesiobuccal aspect of the aforementioned teeth. A titanium molybdenum alloy (TMA spring was attached to the head of miniscrew in one end and ligated to the bracket in the other end to reach the predetermined force. Plaque index (PI, probing pocket depth (PPD, keratinized gingiva (KG, The distance between miniscrew (M.S and gingival level (GL, and bleeding on probing (BOP were recorded before loading and 1, 2, 3, 4 and 5 months post-loading .Results:  All patients completed the study and no complications were reported. Statistically significant intrusion (2.1 ± 0.9 mm was obtained during active treatment. Inserting miniscrews generally was presented with greater sulcus bleeding, plaque accumulation and plaque formation at follow-up visits. There was a statistically significant increase in PI, PPD and BOP indices. Furthermore, the results showed decrease in KG level and M.S to GL level. Conclusion: Miniscrews can provide a clinical benefit as an absolute anchorage device. However, keeping a good oral hygiene is essential to achieve ideal results, because the presence of miniscrews, as a foreign object in mouth, and intrusion force might be harmful for periodontal tissues

  20. Quality of life following third molar removal under conscious sedation

    Science.gov (United States)

    Sancho-Puchades, Manuel; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

    2012-01-01

    Aim: The aim of this study was to assess quality of life (QoL) and degree of satisfaction among outpatients subjected to surgical extraction of all four third molars under conscious sedation. A second objective was to describe the evolution of self-reported pain measured in a visual analogue scale (VAS) in the 7 days after extraction. Study design: Fifty patients received a questionnaire assessing social isolation, working isolation, eating and speaking ability, diet modifications, sleep impairment, changes in physical appearance, discomfort at suture removal and overall satisfaction at days 4 and 7 after surgery. Pain was recorded by patients on a 100-mm pain visual analogue scale (VAS) every day after extraction until day 7. Results: Thirty-nine patients fulfilled correctly the questionnaire. Postoperative pain values suffered small fluctuations until day 5 (range: 23 to 33 mm in a 100-mm VAS), when dicreased significantly. A positive association was observed between difficult ranked surgeries and higher postoperative pain levels. The average number of days for which the patient stopped working was 4.9. Conclusion: The removal of all third molars in a single appointment causes an important deterioration of the patient’s QoL during the first postoperative week, especially due to local pain and eating discomfort. Key words:Third molar removal, quality of life, sedation. PMID:22926461

  1. A rare case of retained fourth molar teeth in maxilla and mandible. Case report

    OpenAIRE

    Rahnama Mansur; Szyszkowska Anna; Pulawska Marta; Szczerba-Gwozdz Joanna

    2014-01-01

    The study presents a case of the rarely occurring totally retained fourth molar teeth simultaneously in maxilla and mandible. The appearance of supernumerary teeth is a relatively uncommon dental anomaly and it is rare for patients to have impacted fourth molars in two quadrant. The aim of this work is to describe the presence of unilateral (right) fourth molars in the maxilla and the mandible in a young female patient aged 24 years. Orthopantomogram revealed impacted lower third molars but a...

  2. Characterization on the Mean Molar Absorptivity of Amino Acids in Microbial Lipopeptides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The molar absorption coefficients of each of 14 kinds of amino acids were determined by the spectrophotometric method, and the mean molar absorption coefficients of 37 different mixtures of each with amino acid composition exactly equivalent to that of the peptide chain of the corresponding lipopeptide were determined based on calculation or experimental. The significance of the results is that the mean molar absorption coefficients strongly demonstrate the regular patterns, though different amino acids bear quite different molar absorption coefficients.

  3. Restauraciones cerámicas en molares jóvenes con endodoncia Ceramics restorations in young molars with endodontic

    OpenAIRE

    M. Urdaneta Quintero; L. Yánez de Meléndez; J. Álvarez Zárraga; M. Jimeno Jiménez; C. Soto Mestre

    2009-01-01

    Objetivo: Efectuar restauraciones cerámicas Cerec (feldespática y de dióxido de circonio) en molares jóvenes con endodoncia, para prevenir complicaciones en el aparato estomatognático por la pérdida de estos dientes. Material y métodos: Se describe la confección de restauraciones cerámicas a nivel de la zona molar mandibular derecha de un paciente del género femenino de 18 años de edad, a quien se le realizó radiografía periapical, por presentar dolor espontáneo en el lado derecho mandibular....

  4. Molar Mass and Second Virial Coefficient of Polyethylene Glycol by Vapor Pressure Osmometry

    Science.gov (United States)

    Schwinefus, Jeffrey J.; Checkal, Caleb; Saksa, Brian; Baka, Nadia; Modi, Kalpit; Rivera, Carlos

    2015-01-01

    In this laboratory experiment, students determine the number-average molar masses and second virial coefficients of polyethylene glycol (PEG) polymers ranging in molar mass from 200 to 1500 g mol[superscript -1] using vapor pressure osmometry (VPO). Students assess VPO in relation to accurate molar mass calculations of PEG polymers. Additionally,…

  5. Densities and volume properties of (water + tert-butanol) over the temperature range of (274.15 to 348.15) K at pressure of 0.1 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, Gennadiy I., E-mail: gie@isc-ras.r [Laboratory of Structure and Dynamics of Molecular and Ion-Molecular Solutions, Institute of Solution Chemistry, Russian Academy of Sciences, 1 Akademicheskaya Street, 153045 Ivanovo (Russian Federation); Makarov, Dmitriy M. [Laboratory of Structure and Dynamics of Molecular and Ion-Molecular Solutions, Institute of Solution Chemistry, Russian Academy of Sciences, 1 Akademicheskaya Street, 153045 Ivanovo (Russian Federation)

    2011-03-15

    The densities of {l_brace}water (1) + tert-butanol (2){r_brace} binary mixture were measured over the temperature range (274.15 to 348.15) K at atmospheric pressure using 'Anton Paar' digital vibrating-tube densimeter. Density measurements were carried out over the whole concentration range at (308.15 to 348.15) K. The following volume parameters were calculated: excess molar volumes and thermal isobaric expansivities of the mixture, partial molar volumes and partial molar thermal isobaric expansivities of the components. Concentration dependences of excess molar volumes were fitted with Redlich-Kister equation. The results of partial molar volume calculations using four equations were compared. It was established that for low alcohol concentrations at T {<=} 208 K the inflection points at x{sub 2} {approx} 0.02 were observed at concentration dependences of specific volume. The concentration dependences of partial molar volumes of both water and tert-butanol had extremes at low alcohol content. The temperature dependence of partial molar volumes of water had some inversion at x{sub 2} {approx} 0.65. The temperature dependence of partial molar volumes of tert-butanol at infinite dilution had minimum at {approx}288 K. It was discovered that concentration dependences of thermal isobaric expansivities of the mixture at small alcohol content and low temperatures passed through minimum.

  6. Thermodynamics of the Apparent Horizon in FRW Universe with Massive Gravity

    Institute of Scientific and Technical Information of China (English)

    LI Hui; ZHANG Yi

    2013-01-01

    Applying Clausius relation with energy-supply defined by the unified first law of thermodynamics formalism to the apparent horizon of a massive gravity model in cosmology proposed lately,the corrected entropic formula of the apparent horizon is obtained with the help of the modified Friedmann equations.This entropy-area relation,together with the identified Misner-Sharp internal energy,verifies the first law of thermodynamics for the apparent horizon with a volume change term for consistency.On the other hand,by means of the corrected entropy-area formula and the Clausius relation δQ =T dS,where the heat flow δQ is the energy-supply of pure matter projecting on the vector ξ tangent to the apparent horizon and should be looked on as the amount of energy crossing the apparent horizon during the time interval dt and the temperature of the apparent horizon for energy crossing during the same interval is 1/(2π(r)A),the modified Friedmann equations governing the dynamical evolution of the universe are reproduced with the known energy density and pressure of massive graviton.The integration constant is found to correspond to a cosmological term which could be absorbed into the energy density of matter.Having established the correspondence of massive cosmology with the unified first law of thermodynamics on the apparent horizon,the validity of the generalized second law of thermodynamics is also discussed by assuming the thermal equilibrium between the apparent horizon and the matter field bounded by the apparent horizon.It is found that,in the limit Hc → 0,which recovers the Minkowski reference metric solution in the flat case,the generalized second law of thermodynamics holds if α3 + 4α4 < 0.Without this condition,even for the simplest model of dRGT massive cosmology with α3 =α4 =0,the generalized second law of thermodynamics could be violated.

  7. Multiple weather factors affect apparent survival of European passerine birds.

    Directory of Open Access Journals (Sweden)

    Volker Salewski

    Full Text Available Weather affects the demography of animals and thus climate change will cause local changes in demographic rates. In birds numerous studies have correlated demographic factors with weather but few of those examined variation in the impacts of weather in different seasons and, in the case of migrants, in different regions. Using capture-recapture models we correlated weather with apparent survival of seven passerine bird species with different migration strategies to assess the importance of selected facets of weather throughout the year on apparent survival. Contrary to our expectations weather experienced during the breeding season did not affect apparent survival of the target species. However, measures for winter severity were associated with apparent survival of a resident species, two short-distance/partial migrants and a long-distance migrant. Apparent survival of two short distance migrants as well as two long-distance migrants was further correlated with conditions experienced during the non-breeding season in Spain. Conditions in Africa had statistically significant but relatively minor effects on the apparent survival of the two long-distance migrants but also of a presumably short-distance migrant and a short-distance/partial migrant. In general several weather effects independently explained similar amounts of variation in apparent survival for the majority of species and single factors explained only relatively low amounts of temporal variation of apparent survival. Although the directions of the effects on apparent survival mostly met our expectations and there are clear predictions for effects of future climate we caution against simple extrapolations of present conditions to predict future population dynamics. Not only did weather explains limited amounts of variation in apparent survival, but future demographics will likely be affected by changing interspecific interactions, opposing effects of weather in different seasons, and

  8. Exodoncia del tercer molar: Factores que determinan complejidad

    Directory of Open Access Journals (Sweden)

    Ivan Manotas Arevalo

    2014-06-01

    Full Text Available ResumenUno de los procedimientos más frecuentes en el campo de la Cirugía Oral es la exodoncia, o extracción dental. La prevención y la promoción de hábitos saludables dentro de los que se cuenta la práctica del cepillado dental, uso de dentífricos, hilo dental y enjuagatorios bucales, además de visitas periódicas de control a especialistas y odontólogos generales e higienistas bucales ha conllevado a una reducción en la perdida de estructuras dentarias por causa de la caries y las periodontopatìas. Sin embargo se mantiene alto el número de exodoncias indicadas por falta de espacio en la estructura de los maxilares para la erupción dental, así como alteraciones en la posición y angulacion de los órganos dentales sobre su eje que impide una adecuada ubicación logrando que se indique su extracción. Dentro de la serie dental los órganos dentarios más frecuentemente afectados por este tipo de alteraciones son los terceros molares. También se mencionan que son esos mismos dientes los que acusan mayor grado de complejidad para realizar el procedimiento de exodoncia, y los que causan mayor grado de morbilidad posquirúrgica en el paciente, con un número mayor de complicaciones y su severidad, descritas en la literatura. (Duazary 2008; 141-147. Este artículo pretende analizar los factores que determinan complejidad en la exodoncia del tercer molar a partir de una revisión bibliografía y comparación de ésta.AbstractOne of the most frequent procedure used in the field of Oral Surgery is extracted, or tooth extraction. The prevention and promoting healthy habits in mind that the practice of brushing teeth, use of toothpastes, mouthwashes and dental floss mouth, in addition to regular monitoring visits to specialists and general dentists and oral hygiene has led to a reduction in the loss of structures caused by tooth decay and periodontal pathology. However remains high number of extractions indicated by lack of space in the

  9. Assessment of the relationship between the maxillary molars and adjacent structures using cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yun Hoa; Cho, Bong Hae [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2012-09-15

    This study investigated the relationship between the roots of the maxillary molars and the maxillary sinus using cone beam computed tomography (CBCT), and measured the distances between the roots of the maxillary molars and the sinus floor as well as the thickness of the bone between the root and the alveolar cortical plate. The study sample consisted of 83 patients with normally erupted bilateral maxillary first and second molars. A total of 332 maxillary molars were examined using CBCT images. The vertical relationship of each root with the maxillary sinus was classified into four types on CBCT cross-sectional images. The distance between the sinus floor and root and the bone thickness between the root and alveolar cortical plate were measured. In the buccal roots of the maxillary molars, a root protruding into the sinus occurred most frequently. A root projecting laterally along the sinus cavity was most common in the palatal roots of the maxillary first molars. The mesiobuccal roots of the maxillary second molar were closest to the sinus. The mesiobuccal roots of the first molars were closest to the cortical plate. The relationship between the roots of the maxillary molars and the sinus differed between the buccal and palatal roots. A root protruding into the sinus occurred more frequent in the buccal roots of the maxillary molars. The mesiobuccal root of the maxillary second molar was closest to the maxillary sinus floor and farthest from the alveolar cortical plate.

  10. Compensation trends of the angulation of first molars:retrospective study of 1 403 malocclusion cases

    Institute of Scientific and Technical Information of China (English)

    Hong Su; Bing Han; Sa Li; Bin Na; Wen Ma; Tian-Min Xu

    2014-01-01

    We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First, angulation of the upper first molar varied significantly with age and tipped most distally in cases aged ,12 years and least distally in cases aged .16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.

  11. Modified distal shoe appliance for the loss of a primary second molar: a case report.

    Science.gov (United States)

    Dhull, Kanika Singh; Bhojraj, Nandlal; Yadav, Shweta; Prabhakaran, Sheeja Devi

    2011-01-01

    Preservation of primary teeth until their normal exfoliation plays a crucial role in preventive and interceptive dentistry. Premature loss of the primary second molar prior to the eruption of the permanent first molar in the absence of the primary second molar can lead to mesial movement and migration of the permanent molar before and during its eruption. In such cases, an intra-alveolar type of space maintainer to guide the eruption of the permanent first molar is indicated. In certain cases, however, the conventional design is not practical. This paper describes a new design for distal shoe appliances in cases of primary second molar loss prior to the eruption of the permanent mandibular first molar.

  12. Cameriere's third molar maturity index in assessing age of majority.

    Science.gov (United States)

    Galić, Ivan; Lauc, Tomislav; Brkić, Hrvoje; Vodanović, Marin; Galić, Elizabeta; Biazevic, Maria Gabriela Haye; Brakus, Ivan; Badrov, Jozo; Cameriere, Roberto

    2015-07-01

    Estimation of chronological age of an individual is one of the main challenges in forensic science. Legally to be able to treat a person as a minor or an adult, it is necessary to determine whether their age of majority (if they are older or younger than 18, in most countries). Methods for estimating age are especially important when an individual in question lacks personal documents or other means of identification. As the dental age differs in various populations, the aim of this study was to evaluate applicability of third molar method for assessing age of majority in Croatia. Cameriere's third molar maturity index (I3M) value of 0.08, measured by the open apices of the teeth, was verified in sample of 1336 panoramic images aged between 14 and 23 years. Chronological age gradually decreased as I3M increased in both genders. Males showed statistically significant advanced maturation when I3M was between 0.0 and 0.3 value. The results indicate that the sensitivity of the test for 0.08 value was 84.3% (95%CI 80.6%, 87.5%) for females and 91.2% (95%CI 88.7%, 93.1) for males. Specificity was 95.4% (95%CI 92.5%, 97.5%) and 91.9% (95%CI 88.8%, 94.3%). The proportions of accurately classified males were 88.8% and that of females 91.5%. The estimated post-test probabilities, of individuals, in other word the probability that a Croatian individual with an I3Mthird molar maturity index should be used as a determinant of the age of majority in Croatia.

  13. [Molar incisor hypomineralization (MIH)--a literature review].

    Science.gov (United States)

    Gotler, M; Ratson, T

    2010-04-01

    MIH was defined by Weerheijm (2001) as "hypomineralisation of systemic origin of 1-4 permanent first molars, frequently associated with affected incisors". The prevalence of MIH varies between 2.8% and 25%, dependent upon the study. At their sixth congress in 2003, The European Association of pediatric dentistry defined criteria for diagnosis of the phenomena. It included the presence of demarcated opacity, posteruptive enamel breakdown, atypical restoration, extracted molar due to MIH and unerupted teeth. According to the teeth involved and to the time of the crown formation, researches focused on environmental and systemic conditions as possible reasons for MIH.The etiologies were divided into five groups: Exposure to environmental contaminants, pre/peri and neonatal problems, exposure to fluoride, common childhood illnesses and medically compromised children. The clinical implications include highly sensitive teeth, difficulty to achieve adequate anesthesia, behavioral problems and anxiety, rapid progression of caries and the esthetic implications. A six step approach to management was described suggested: risk identification, early diagnosis, remineralization and desensitization, prevention of caries and posteruption breakdown, restorations and extractions and finally maintenance. Restoring an affected molar can vary from adhesive intra coronal restorations (resin composite is the material of choice) to extra coronal restorations (e.g. preformed metal crown). Esthetic solutions to affected incisors may include microabrasion (that shows little improvement) and resin composite or porcelain veneer. The key for a successful treatment is early diagnosis, intense follow up and usage of remineralizating agents as soon as the teeth erupt. There is still need for further research to clarify the etiological factors and improve the durability of restoration in affected teeth.

  14. Patterning by heritage in mouse molar row development.

    Science.gov (United States)

    Prochazka, Jan; Pantalacci, Sophie; Churava, Svatava; Rothova, Michaela; Lambert, Anne; Lesot, Hervé; Klein, Ophir; Peterka, Miroslav; Laudet, Vincent; Peterkova, Renata

    2010-08-31

    It is known from paleontology studies that two premolars have been lost during mouse evolution. During mouse mandible development, two bud-like structures transiently form that may represent rudimentary precursors of the lost premolars. However, the interpretation of these structures and their significance for mouse molar development are highly controversial because of a lack of molecular data. Here, we searched for typical tooth signaling centers in these two bud-like structures, and followed their fate using molecular markers, 3D reconstructions, and lineage tracing in vitro. Transient signaling centers were indeed found to be located at the tips of both the anterior and posterior rudimentary buds. These centers expressed a similar set of molecular markers as the "primary enamel knot" (pEK), the signaling center of the first molar (M1). These two transient signaling centers were sequentially patterned before and anterior to the M1 pEK. We also determined the dynamics of the M1 pEK, which, slightly later during development, spread up to the field formerly occupied by the posterior transient signaling center. It can be concluded that two rudimentary tooth buds initiate the sequential development of the mouse molars and these have previously been mistaken for early stages of M1 development. Although neither rudiment progresses to form an adult tooth, the posterior one merges with the adjacent M1, which may explain the anterior enlargement of the M1 during mouse family evolution. This study highlights how rudiments of lost structures can stay integrated and participate in morphogenesis of functional organs and help in understanding their evolution, as Darwin suspected long ago. PMID:20709958

  15. Precursory specialties of apparent stresses in Yunnan earthquake series

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-gui; LIU Jie; DING Ye-ling; SUN Ye-jun; YU Xin

    2006-01-01

    On the basis of the assumption that ω2 model accords with source displacement spectra, we have obtained the mathematical expressions for calculating apparent stresses of moderate-small shocks from low-frequency flat level and comer frequency. By using digital seismic records, apparent stress values are calculated for 823 moderate-small shocks of 4 earthquake series in Yunnan area following corrections for instrument response, propagation influence and site effect. The results show that for the 4 earthquake series in Yunnan area, apparent stress hints precursory information, which means that if a moderate-small shock occurs with apparent stress larger than 1 MPa in an earthquake series, a moderate-strong earthquake will occur afterwards; and if there is not moderate-small shock with apparent stress larger than 1 MPa after a moderate-strong event in an earthquake series, strong aftershock will not occur. The research also indicates that the average apparent stress value is 0.8 MPa in Yunnan area, therefore, apparent stress is not obviously related to seismic magnitude.

  16. The effect of visual apparent motion on audiovisual simultaneity.

    Science.gov (United States)

    Kwon, Jinhwan; Ogawa, Ken-ichiro; Miyake, Yoshihiro

    2014-01-01

    Visual motion information from dynamic environments is important in multisensory temporal perception. However, it is unclear how visual motion information influences the integration of multisensory temporal perceptions. We investigated whether visual apparent motion affects audiovisual temporal perception. Visual apparent motion is a phenomenon in which two flashes presented in sequence in different positions are perceived as continuous motion. Across three experiments, participants performed temporal order judgment (TOJ) tasks. Experiment 1 was a TOJ task conducted in order to assess audiovisual simultaneity during perception of apparent motion. The results showed that the point of subjective simultaneity (PSS) was shifted toward a sound-lead stimulus, and the just noticeable difference (JND) was reduced compared with a normal TOJ task with a single flash. This indicates that visual apparent motion affects audiovisual simultaneity and improves temporal discrimination in audiovisual processing. Experiment 2 was a TOJ task conducted in order to remove the influence of the amount of flash stimulation from Experiment 1. The PSS and JND during perception of apparent motion were almost identical to those in Experiment 1, but differed from those for successive perception when long temporal intervals were included between two flashes without motion. This showed that the result obtained under the apparent motion condition was unaffected by the amount of flash stimulation. Because apparent motion was produced by a constant interval between two flashes, the results may be accounted for by specific prediction. In Experiment 3, we eliminated the influence of prediction by randomizing the intervals between the two flashes. However, the PSS and JND did not differ from those in Experiment 1. It became clear that the results obtained for the perception of visual apparent motion were not attributable to prediction. Our findings suggest that visual apparent motion changes temporal

  17. Aberrant anatomy of a maxillary first molar: A case report

    Directory of Open Access Journals (Sweden)

    Mansi Atri

    2016-01-01

    Full Text Available The first step of successful endodontic treatment is to gain access to the pulp chamber and find all of the canals. To achieve this goal, practitioners need to be familiar with all possible variations of the root canal and have adequate information of the tooth that needs treatment. The present case report describes an anatomical variant of the maxillary second molar with six canals, a variation that has not been previously reported. Helpful hints for the detection of the unusual canal are presented.

  18. La cirugía periapical de los molares

    OpenAIRE

    Gay Escoda, Cosme; Paredes García, Jordi; Berini Aytés, Leonardo

    1993-01-01

    Se han estudiado 65 pacientes sometidos a intervención quirúrgica periapical en 72 molares ( 120 raíces y 155 conductos radiculares). Se analizó una serie de características preoperatorias (edad, antecedentes patológicos, patologías asociadas, distribución de dientes afectados, tamaño de la lesión periapical, tipo de endodoncia ortógrafa y calidad radiológica de la endodoncia previa), peroperatorias (tipo de incisión, existencia de comunicación oroantral, afectación cortical, tamaño de la res...

  19. Peripheral facial nerve paralysis after upper third molar extraction.

    Science.gov (United States)

    Cakarer, Sirmahan; Can, Taylan; Cankaya, Burak; Erdem, Mehmet Ali; Yazici, Sinem; Ayintap, Emre; Özden, Ali Veysel; Keskin, Cengizhan

    2010-11-01

    Peripheral facial nerve paralysis (PFNP) after mandibular interventions has been reported in the literature. In most cases, paralysis begins immediately after the injection of the mandibular anesthesia, and duration of facial weakness is less than 12 hours. However, there are few documented cases of PFNP after maxillary dental or surgical procedures. A variety of mechanisms have been associated to PFNP, including viral reactivation, demyelination, edema, vasospasm, and trauma. The purpose of this presentation was to report a rare case of facial paralysis that occurred after an upper third molar extraction. The cause of the PFNP and the importance of the multidisciplinary approach in the management are emphasized.

  20. Human age estimation combining third molar and skeletal development.

    Science.gov (United States)

    Thevissen, P W; Kaur, J; Willems, G

    2012-03-01

    The wide prediction intervals obtained with age estimation methods based on third molar development could be reduced by combining these dental observations with age-related skeletal information. Therefore, on cephalometric radiographs, the most accurate age-estimating skeletal variable and related registration method were searched and added to a regression model, with age as response and third molar stages as explanatory variable. In a pilot set up on a dataset of 496 (283 M; 213 F) cephalometric radiographs, the techniques of Baccetti et al. (2005) (BA), Seedat et al. (2005) (SE), Caldas et al. (2007) and Rai et al. (2008) (RA) were verified. In the main study, data from 460 (208 F, 224 M) individuals in an age range between 3 and 26 years, for which at the same day an orthopantogram and a cephalogram were taken, were collected. On the orthopantomograms, the left third molar development was registered using the scoring system described by Gleiser and Hunt (1955) and modified by Köhler (1994) (GH). On the cephalograms, cervical vertebrae development was registered according to the BA and SE techniques. A regression model, with age as response and the GH scores as explanatory variable, was fitted to the data. Next, information of BA, SE and BA + SE was, respectively, added to this model. From all obtained models, the determination coefficients and the root mean squared errors were calculated. Inclusion of information from cephalograms based on the BA, as well as the SE, technique improved the amount of explained variance in age acquired from panoramic radiographs using the GH technique with 48%. Inclusion of cephalometric BA + SE information marginally improved the previous result (+1%). The RMSE decreased with 1.93, 1.85 and 2.03 years by adding, respectively, BA, SE and BA + SE information to the GH model. The SE technique allows clinically the fastest and easiest registration of the degree of development of the cervical vertebrae. Therefore, the choice of

  1. Multiple unerupted mandibular permanent molar teeth: a case report

    Directory of Open Access Journals (Sweden)

    Kaan Gündüz

    2012-04-01

    Full Text Available

    The multiple impacted teeth at jaws are a rare condition that frequently associated with syndromes, metabolic disorders or trauma. A 48-year old male patient was referred to our clinic, with complaint of pain on right retromolar region while chewing. The patient had facial asymmetry and restricted mouth opening. Clinical and radiographic examination revealed the impaction of mandibular first, second and third molar and an abnormal condyle and coronoid process. All of the impacted teeth were extracted. Because the patient refused other treatment procedures no surgical intervention was performed for the asymmetry and restricted mouth opening. Six months clinic and radiographic follow up were satisfactory.

  2. Pericoronitis, deep fascial space infections, and the impacted third molar.

    Science.gov (United States)

    Litonjua, L S

    1996-01-01

    Patients consulting the Philippine General Hospital Dentistry Department for management of impacted mandibular third molars were studied for the presence of pericoronits and deep fascial space infections. 18% of total cases presented an infection, while 13% presented with pericoronitis. 11% presented with deep fascial infection of which 72% were secondary to pericoronitis. A radiographic evaluation showed the vertical angulation (68%) with the highest portion at or above the occlusal level (70%) associated the most with pericoronits. The potential of pericoronitis developing to a deep space infection should always be considered.

  3. Restoration of Endodontically Treated Molars Using All Ceramic Endocrowns

    Directory of Open Access Journals (Sweden)

    Roopak Bose Carlos

    2013-01-01

    Full Text Available Clinical success of endodontically treated posterior teeth is determined by the postendodontic restoration. Several options have been proposed to restore endodontically treated teeth. Endocrowns represent a conservative and esthetic restorative alternative to full coverage crowns. The preparation consists of a circular equigingival butt-joint margin and central retention cavity into the entire pulp chamber constructing both the crown and the core as a single unit. The case reports discussed here are moderately damaged endodontically treated molars restored using all ceramic endocrowns fabricated using two different systems, namely, CAD/CAM and pressed ceramic.

  4. A comparison of concentration measurement techniques for the estimation of the apparent mass diffusion coefficient

    Directory of Open Access Journals (Sweden)

    L.M. Pereira

    2001-09-01

    Full Text Available In this article we compare two different techniques to measure the concentration of saline solutions for the identification of the apparent mass diffusion coefficient in soils saturated with distilled water. They are the radiation measurement technique and the electrical conductivity measurement technique. These techniques are compared in terms of measured quantities, sensitivity coefficients with respect to unknown parameters and the determinant of the information matrix. The apparent mass diffusion coefficient is estimated by utilizing simulated measurements containing random errors. The Levenberg-Marquardt method of minimization of the least-squares norm is used as the parameter estimation procedure. The effects of the volume of saline solution injected into the column devised for the experiments on the accuracy of the estimated parameters are also addressed in this article.

  5. Apparent Ionic Charge in Electrolyte and Polyelectrolyte Solutions

    Science.gov (United States)

    Magdelenat, H.; And Others

    1978-01-01

    Compares average displacements of charged particles under thermal motion alone with those obtained by the action of an external electric field to develop a concept of "apparent charge" to approximate actual structural charge in an electrolyte solution. (SL)

  6. Differential Expression of p63 in Hydropic and Molar Gestations

    International Nuclear Information System (INIS)

    Objective:To observe the differential expression of p63 in hydropic and molar gestation. Study Design: Cross-sectional analytical study. Place and Duration of Study: Department of Pathology, Basic Medical Sciences Institute, Jinnah Postgraduate and Medical Centre, Karachi, from January 2006 to June 2013. Methodology: Ninety placental biopsies including 30 cases each of hydropic abortions, partial hydatidiform mole and complete hydatidiform mole were analyzed for morphological features and results of immunohistochemical staining. Results were described as frequency. Significance was determined using test of proportions with significance at p < 0.05. Results: Out of 30 cases of hydropic abortion, 6 were negative, 15 were weak, 4 were moderate and 5 showed strong degree of intensity for p63. Out of 30 cases of partial hydatidiform mole, 3 were negative, 2 showed weak, 4 showed moderate and 21 cases showed strong degree of intensity for p63. All 30 cases of complete hydatidiform mole strongly stained for p63. Conclusion: The intensity of staining of p63 was stronger in cases of molar pregnancy as compared to hydropic abortion. There was loss of p63 expression in cytotrophoblastic cells in all abortions. In limited resources settings, where facilities for PCR/FISH and DNA ploidy analysis is not available, the authors advocate p63 in routine clinical practice to provide the most refined diagnosis of hydatidiform moles. (author)

  7. Prevalence of cervical enamel projection in human molars

    Directory of Open Access Journals (Sweden)

    Maria Regina Lima de Souza

    2014-01-01

    Full Text Available Introduction : One of the developmental anomalies of dental enamel is cervical enamel projection (CEP. The aim of this study was to assess the prevalence of CEP in maxillary and mandibular human teeth. Materials and Methods: A total of 234 human molars obtained from the tooth bank of the State University of Amazonas were used in the present study. CEP was classified as Grade 0 (absence of projection, Grade I (discrete extension of cementoenamel junction toward the furcation, Grade II (closer to furcation without invasion, and Grade III (extending to the furcation area. The evaluation was performed using macroscopic inspection of teeth faces (buccal, lingual/palatal, mesial, and distal with at least one-third of the crown on each face. Results: It was found that 17.1% of the teeth evaluated had CEP, but neither of the projections occurred on the proximal faces. Higher prevalence of CEP was found on the buccal faces and the most commonly grade of CEP found was Grade I (10.3%. Conclusions: It may be concluded that CEP occurs more frequently in mandibular molars and its diagnosis is extremely important since these projections may difficult bacterial plaque removal, leading to an inflammatory process and unnecessary endodontic treatment.

  8. Supplemental root in a mandibular first molar: a rarity

    Directory of Open Access Journals (Sweden)

    Poonam Mahajan

    2011-04-01

    Full Text Available Anatomic variations are common in human dentition. A clear understanding of these variations is very important for success of endodontic treatment. A dentist should be aware of these anatomic variations as this can affect the treatment outcome. A case of endodontic therapy is presented in which inability to locate an anatomically rare supplemental canal of a three rooted mandibular first molar resulted in treatment failure. A 21-year-old female reported with pain and swelling in relation to lower right first molar. An intra oral periapical radiograph revealed 3 roots; the first canal of the mesial root and a canal of one of the distal roots were found to be treated endodontically, which were infraobturated but the canal of the 2nd distal root had not been treated. The radiograph revealed periapical radiolucency and widening of periodontal space. Prior to starting the endodontic treatment the clinician must be aware of the anatomic variations in tooth pulp morphology and also the importance of preoperative radiographs cannot be underscored.

  9. Finding Apparent Horizons in Dynamic 3D Numerical Spacetimes

    OpenAIRE

    Anninos, P.; Camarda, K.; Libson, J.; Masso, J.; Seidel, E; Suen, W.

    1996-01-01

    We have developed a general method for finding apparent horizons in 3D numerical relativity. Instead of solving for the partial differential equation describing the location of the apparent horizons, we expand the closed 2D surfaces in terms of symmetric trace--free tensors and solve for the expansion coefficients using a minimization procedure. Our method is applied to a number of different spacetimes, including numerically constructed spacetimes containing highly distorted axisymmetric blac...

  10. Analysis of Apparent Elasticity Constants of Woven Fabrics

    Institute of Scientific and Technical Information of China (English)

    董侠; 张建春; 张燕

    2001-01-01

    The woven fabric can be defined as orthogonal elastomer if the extension force that puts on the fabric is very small. Based on the precondition, the apparent elasticity constants of a woven fabric were analyzed theoretically in the paper. The bias angle (which is between weft yarns and extension direction ) affects apparent elasticity modulus and elasticity coefficient of the fabric in the extension direction. And the experiment describes fluxes of elasticity constants going with the bias angle of the fabric.

  11. Comparison of Primary Molar Crown Dimensions with Stainless Steel Crowns in a Sample of Iranian Children.

    Science.gov (United States)

    Afshar, Hossein; Kamali Sabeti, Arghavan; Shahrabi, Mahdi

    2015-01-01

    Background and aims. Due to anatomic variation in tooth anatomy between populations, this study compared the buccolingual (BL) and mesiodistal (MD) dimensions of primary molars with those of stainless steel crowns (SSCs) in anIranian population. Materials and methods. Impressions were taken from both dental arches of children, and casts were poured. Teeth with caries, restoration, hypoplasia or other dental anomalies were excluded. 216 primary molars were selected and divided into 4 groups of 54 each (maxillary and mandibular first and second primary molars). MD/BL dimensions were measured using a digital caliper with 0.01 mm precision on casts and SCCs (3M brand). Data were assessed using paired t-test, post hoc test and ANOVA. P < 0.05 was considered statistically significant. Results. The MD dimension of the lower first molar SSC and the BL dimension of the lower second molar SSC had the least difference with the corresponding values of the respective teeth. The MD dimension of the upper second molar SSC and the BL dimension of the upper first molar SSC had the greatest difference with the corresponding values in the respective teeth. Comparison of the two different brands of SSCs for the upper first molar revealed that both types had significant differences with the teeth in terms of both MD (P = 0.0) and BL (P = 0.0) dimensions. Conclusion. In the studied population, best adaptation was seen in second lower molars and the least adaptationswere seen in first and second upper molars.

  12. Estudo morfológico da polpa de molares de ratos Wistar frente a uma oclusão traumática experimental Morphological study of the pulp of Wistar rats molars under experimental occlusal interference

    Directory of Open Access Journals (Sweden)

    Luiz Alberto Plácido PENNA

    2000-06-01

    Full Text Available As alterações morfológicas pulpares, decorrentes de um estímulo externo experimental (interferência oclusal, foram estudadas, em nível de microscopia de luz. Utilizaram-se restaurações de amálgama, em sobreoclusão nos primeiros molares superiores direitos de dez ratos Wistar, divididos em 3 grupos e sacrificados por perfusão transcardíaca com formol a 10%, aos 10, 20 e 30 dias. A avaliação foi feita nos molares inferiores direitos (lado experimental e esquerdos (lado controle. As peças ósseas após descalcificação em solução de EDTA associada às microondas, seguiram técnica histológica de rotina e coloração por hematoxilina-eosina e tricrômico de Mallory. Verificou-se no lado controle uma reação intensa caracterizada por um posicionamento atípico dos odontoblastos, seguida pelo aparecimento de cálculos pulpares e posteriormente por uma aparente e uniforme acomodação tecidual em toda a polpa, com moderada incidência de fibras colágenas. No lado experimental, as alterações foram similares parecendo, porém, aumentar com o tempo, principalmente aos 30 dias, onde a imagem histológica era semelhante à do lado controle aos 10 dias. Os resultados obtidos permitiram concluir que a interferência oclusal provocou alterações no tecido conjuntivo pulpar tanto no lado experimental como no controle e que as mesmas foram proporcionais à direção dos movimentos mandibulares.Pulpal morphological alterations in mandibular molars of rats, resulting from an experimental external stimulus (occlusal interference, were studied using light microscopy. We placed amalgam restorations in supraocclusion in the right superior first molars of 10 Wistar rats divided into three groups, which were sacrificed by transcardiac perfusion with 10% formalin, after 10, 20 and 30 days. The evaluation of the right (experimental side and left (control side inferior molars was made after decalcification of the bony specimens with EDTA solution

  13. Correlation of acute pericoronitis and the position of the mandibular third molar.

    Science.gov (United States)

    Leone, S A; Edenfield, M J; Cohen, M E

    1986-09-01

    Acute pericoronitis is a painful, debilitating infection that is most commonly found among young adults with erupting mandibular third molars. Prophylactic removal of third molars to prevent this disease has been advocated, but this procedure requires an accurate description of the third molar at highest risk for this infection. Clinical and radiographic measurements were compared in 25 diseased subjects and 109 normal subjects. Of 10 variables significantly related to the presence of acute pericoronitis, stepwise discriminant analysis selected 4 variables that produced a canonical correlation coefficient of 0.71. In clinical terms, these variables described the tooth at highest risk for acute pericoronitis as a fully erupted, vertical mandibular third molar that is in contact with the adjacent second molar, at or above the occlusal plane, and partially encapsulated by soft or hard tissues. Prophylactic treatment of these third molars is highly recommended.

  14. A rare case of retained fourth molar teeth in maxilla and mandible. Case report

    Directory of Open Access Journals (Sweden)

    Rahnama Mansur

    2014-06-01

    Full Text Available The study presents a case of the rarely occurring totally retained fourth molar teeth simultaneously in maxilla and mandible. The appearance of supernumerary teeth is a relatively uncommon dental anomaly and it is rare for patients to have impacted fourth molars in two quadrant. The aim of this work is to describe the presence of unilateral (right fourth molars in the maxilla and the mandible in a young female patient aged 24 years. Orthopantomogram revealed impacted lower third molars but also unerupted unilateral (right upper and lower fourth molars. Before orthodontic treatment, the patient was subsequently admitted for removal of third and fourth impacted upper and lower molars under local anesthesia.

  15. Indirect pulp capping in primary molar using glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Murtia Metalita

    2014-12-01

    Full Text Available Background: Indirect pulp capping in primary teeth, however, is more rarely conducted than permanent teeth, since it thought to have low impact and most suggestion is for taking caries lesion aggressively on primary teeth. Purpose: The study was aimed to evaluate the subjective complaint, clinical symptom, and radiographic appearance of indirect pulp capping treatment using glass ionomers cements in primary molar. Methods: Sixteen children in range of age 6 to 8 years old, who visited Clinic of Pediatric Dentistry Universitas Airlangga Dental Hospital, Surabaya Indonesia, were the subject of study. They had one occlusal dental caries on one side of maxillary or mandibular primary molar with the diagnose of pulpitis reversible. The experimental group, had indirect pulp capping treatment with glass ionomer cements (GC Fuji VII®, while the control group, had indirect pulp capping treatment with calcium hydroxide (Metapaste. Each group was filled with GC Fuji IX® as permanent restoration. After one week, one month, and three months later, the observations were made on subjective complaint, clinical symptom, and radiographic appearance. Results: The results showed no subjective complaint such as pain or problem on mastication; no negative clinical symptoms such as pain on palpation, gingivitis or periodontitis, and abnormal tooth mobility; no negative radiographic appearance such as pathological apical radioluscency, internal or external resorbtion, and change of ligament periodontal widthafter the treatment. Conclusion: The study suggested that indirect pulp capping treatment using glass ionomer cement materials on primary teeth might be considered to be the treatment choice.Latar belakang: Indirect pulp capping pada gigi sulung lebih jarang dilakukan dibandingkan gigi permanen, karena dianggap memiliki dampak yang rendah dan sebagian besar menyarankan untuk mengambil lesi karies secara agresif pada gigi sulung. Tujuan: Penelitian ini bertujuan

  16. Analgesic regimens for third molar surgery: pharmacologic and behavioral considerations.

    Science.gov (United States)

    Moore, P A; Werther, J R; Seldin, E B; Stevens, C M

    1986-11-01

    The level of pain following the extraction of impacted third molars was evaluated in 75 patients. Participants were administered acetaminophen 1,000 mg or a placebo before surgery. After surgery, acetaminophen 650 mg was administered either at fixed intervals or as needed to relieve pain. When acetaminophen was administered before surgery, the onset of peak pain was delayed and patient discomfort was decreased 3, 4, and 5 hours after surgery. Patients following the fixed interval regimen after surgery experienced more pain overall and requested the backup narcotic analgesic more frequently. Of the regimens tested, patients preferred the regimen of acetaminophen 1,000 mg administered before surgery with acetaminophen administered as needed for pain after surgery. PMID:3465787

  17. Single implant in the mandibular molar region of edentulous patient.

    Science.gov (United States)

    Zhai, Jun-Jiang; Wen, Cai; Teng, Ming-Hua; Liang, Xing

    2013-09-01

    Implant-retained overdentures are a valid treatment option for edentulous patients, especially for patients with severe alveolar ridge atrophy. A central single implant is considered adequate to retain an overdenture in the edentulous mandible. However, for some patients, there is no sufficient bone height, or width in the interforaminal region of the mandible for insertion of the implant. This case report illustrates that the insertion of a single implant in the mandibular molar region might stabilize the prosthesis, and might improve the oral health-related quality of life and chewing function. A Locator attachment was used in this case to retain the overdenture. The one-year clinical results are promising. However, long-term clinical results and randomized clinical trials are needed before this method can be widely used in clinical application.

  18. Molar extinction coefficients of solutions of some organic compounds

    Science.gov (United States)

    Singh, Kulwant; Sandhu, G. K.; Lark, B. S.

    2004-05-01

    Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH_{3}NO), N-methylformamide (C_{2}H_{5}NO), NN-dimethylformamide (C_{3}H_{7}NO), NN-dimethylacetamide (C_{4}H_{9}NO), 1,4-dioxane (C_{4}H_{8}O_{2}), succinimide (C_{4}H_{5}NO_{2}) and solutions of acetamide (C_{2}H_{5}NO) and benzoic acid (C_{7}H_{6}O_{2}) in 1,4-dioxane (C_{4}H_{8}O_{2}) have been determined by narrow beam gamma-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental values of mass attenuation coefficients of these compounds have been used to calculate effective atomic numbers and electron densities. The additivity rule earlier used for aqueous solution has been extended to non-aqueous (1,4-dioxane) solutions.

  19. Management of mandibular first molar with four canals in mesial root

    OpenAIRE

    Subbiya, Arunajatesan; Kumar, Krishnamurthy Sathish; Vivekanandhan, Paramasivam; Prakash, Venkatachalam

    2013-01-01

    Successful root canal treatment depends on adequate cleaning, shaping, and filling of the root canal system. The presence of middle mesial (MM) root canal of mandibular molars has been reported by various authors. But incidence of four canals in mesial root of mandibular molar is very rare. The aim of this case report is to present and describe the identification and management of a mandibular first molar with four canals in the mesial root and single canal in the distal root.

  20. Ovarian Malignant Mixed Germ Cell Tumor: A Case of Unusual Presentation as Molar Pregnancy

    OpenAIRE

    Aminimoghaddam, Soheila; Mohseni, Iman; Afzalzadeh, Azadeh; Esmaeeli, Shooka

    2016-01-01

    Background: This research was conducted to introduce a patient with rare ovarian mixed germ cell tumor, presented as molar pregnancy. Case Presentation: The patient was a 16 year old woman admitted with diagnosis of molar pregnancy. Abdominal enlargement was the only complaint. She had a large pelvic mass in physical examination. The first diagnosis was molar pregnancy due to previous ultrasonic reports and positive βeta HCG. Urine pregnancy test was positive. As suction curettage was perform...

  1. Prevalence of missing and impacted third molars in adults aged 25 years and above

    OpenAIRE

    Jung, Yun-Hoa; Cho, Bong-Hae

    2013-01-01

    Purpose The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. Materials and Methods The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent ...

  2. Fate of third molar in line of mandibular angle fracture - Retrospective study

    Directory of Open Access Journals (Sweden)

    Preetha Balaji

    2015-01-01

    Conclusion: The present study fails to identify any concrete factors that would predict the failure of the retained third molar that were involved in the line of mandibular fractures. The proof presented here, especially with low complication rates indicate that all impacted third molar along the line of fracture be removed and unless necessary, the partially erupted teeth would also be extracted. In such a situation, the rate of infection and survival of the third molar would have been entirely different.

  3. Independent and Confluent Middle Mesial Root Canals in Mandibular First Molars: A Report of Four Cases

    Directory of Open Access Journals (Sweden)

    Mohanavelu Deepalakshmi

    2012-01-01

    Full Text Available Mandibular molars demonstrate considerable variations with respect to number of roots and root canals. The possibility of additional root canals should be considered even in teeth with a low frequency of abnormal root canal anatomy. This paper discusses the endodontic management of the rare anatomical complexity middle mesial canals in mandibular first molar and also serves to remind the clinicians that such anatomical variations should be taken into account during the endodontic treatment of the mandibular molars.

  4. Standard molar enthalpies of formation of hydroxy-, chlor-, and bromapatite

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Fernando J.A.L. [Centro de Quimica Estrutural, Complexo Interdisciplinar, Instituto Superior Tecnico 1049-001 Lisbon (Portugal); Minas da Piedade, Manuel E. [Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade de Lisboa, 1749-016 Lisbon (Portugal); Calado, Jorge C.G. [Centro de Quimica Estrutural, Complexo Interdisciplinar, Instituto Superior Tecnico 1049-001 Lisbon (Portugal)]. E-mail: jcalado@ist.utl.pt

    2005-10-15

    The standard (p{sup 0} =0.1MPa) molar enthalpies of formation in the crystalline state of hydroxyapatite, chlorapatite and a preliminary value for bromapatite, at T=298.15K, were determined by reaction-solution calorimetry as: {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2},cr]=-(13399+/-11)kJ.mol{sup -1},{delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}Cl{sub 2},cr]=-(13231+/-82)kJ.mol{sup -1},and{delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}Br{sub 2},cr]=-(13063+/-81)kJ.mol{sup -1}. A critical assessment of these results and of previously published data is made. Finally, the standard molar enthalpy of formation of iodapatite is estimated as {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}I{sub 2},cr]=-12949kJ.mol{sup -1}, from a linear correlation of {delta}{sub f}H{sub m}{sup 0} [Ca{sub 10}(PO{sub 4}){sub 6}X{sub 2},cr] (X=OH, F, Cl, Br) against the corresponding {delta}{sub f}H{sub m}{sup 0} [CaX{sub 2},cr].

  5. Saving the 2nd Molar from the 3rd Is it Really the Guilt of the Tilt?

    Science.gov (United States)

    Yadav, Pankaj; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

    2016-01-01

    Introduction Clinicians often relate the distal caries in second molars to angulated third molars, which if left undetected can lead to gross decay that may further require removal of the tooth. Due to this fact, many third molars are advised for prophylactic removal to prevent decay in the second molar. But this approach would only be justified when the incidence of decay/loss of second molar due to third molar are reasonably high. We sought to determine incidence of caries experience and also sequel extraction in second molars associated with the third molars. Aim The study was conducted to answer the basic question that whether the incidence of caries and subsequent extraction of second molar due to angulated third molars is high enough to justify the prophylactic removal of third molar or not. Materials and Methods This study was conducted on radiographic records of 1187 patients. The effect of tilted third molar on the second molar was measured in relation with three parameters namely level & position of third molar with respect to second molar and the distribution among arches. Results The results indicated that out of total number of teeth examined only 5.4% of maxillary and 9.6% of mandibular second molars were affected by tilted third molars. Further, only 2.2% of mandibular and 2.9% of maxillary second molars were indicated for extraction. The data was statistically insignificant. Conclusion It was concluded that distal caries in second molars is not very common. It may be present in some cases of third molar impactions and prophylactic removal of these impacted teeth may not be considered appropriate. PMID:27437353

  6. Assessment of maxillary third molars with panoramic radiography and cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yun Hoa; Cho, Bong Hae [Dept.of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2015-12-15

    This study investigated maxillary third molars and their relation to the maxillary sinus using panoramic radiography and cone-beam computed tomography (CBCT). A total of 395 maxillary third molars in 234 patients were examined using panoramic radiographs and CBCT images. We examined the eruption level of the maxillary third molars, the available retromolar space, the angulation, the relationship to the second molars, the number of roots, and the relationship between the roots and the sinus. Females had a higher frequency of maxillary third molars with occlusal planes apical to the cervical line of the second molar (Level C) than males. All third molars with insufficient retromolar space were Level C. The most common angulation was vertical, followed by buccoangular. Almost all of the Level C molars were in contact with the roots of the second molar. Erupted teeth most commonly had three roots, and completely impacted teeth most commonly had one root. The superimposition of one third of the root and the sinus floor was most commonly associated with the sinus floor being located on the buccal side of the root. Eruption levels were differently distributed according to gender. A statistically significant association was found between the eruption level and the available retromolar space. When panoramic radiographs showed a superimposition of the roots and the sinus floor, expansion of the sinus to the buccal side of the root was generally observed in CBCT images.

  7. Periodontal considerations in the use of bonds or bands on molars in adolescents and adults.

    Science.gov (United States)

    Boyd, R L; Baumrind, S

    1992-01-01

    This longitudinal study compared the periodontal status of bonded and banded molars in 20 adult and 40 adolescent patients before, during and after treatment with fixed orthodontic appliances. Plaque accumulation (measured by the Plaque Index), gingival inflammation (measured by the Gingival Index and the bleeding tendency), and pocket depth were assessed by one examiner at sites along the mesio-buccal line angle of the maxillary right first molar and the mandibular left first molar. Assessments were made immediately prior to the placement of fixed appliances (pretreatment), at 1, 3, 6, 9, 12 and 18 months after appliances were placed; and 3 months after appliances were removed (posttreatment). Loss of attachment between the pretreatment and posttreatment visits also was determined. At pretreatment, no significant differences were found in gingival inflammation between maxillary and mandibular banded and bonded molars. During treatment, both maxillary and mandibular banded molars showed significantly (p less than 0.05) greater gingival inflammation and plaque accumulation than did bonded molars. Three months after appliance removal, the maxillary molars that had been banded continued to show significantly more gingival inflammation and loss of attachment than did the maxillary molars that had been bonded. When all banded and bonded teeth were grouped by patient age, mean values for plaque accumulation and gingival inflammation in the maxillary molar regions were significantly greater for adolescents than for adults.

  8. Mandibular Third Molar Impaction: Review of Literature and a Proposal of a Classification

    Directory of Open Access Journals (Sweden)

    Gintaras Juodzbalys

    2013-06-01

    Full Text Available Objectives: The purpose of present article was to review impacted mandibular third molar aetiology, clinical anatomy, radiologic examination, surgical treatment and possible complications, as well as to create new mandibular third molar impaction and extraction difficulty degree classification based on anatomical and radiologic findings and literature review results.Material and Methods: Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were mandibular third molar, impacted mandibular third molar, inferior alveolar nerve injury third molar, lingual nerve injury third molar. The search was restricted to English language articles, published from 1976 to April 2013. Additionally, a manual search in the major anatomy and oral surgery journals and books was performed. The publications there selected by including clinical and human anatomy studies.Results: In total 73 literature sources were obtained and reviewed. Impacted mandibular third molar aetiology, clinical anatomy, radiographic examination, surgical extraction of and possible complications, classifications and risk factors were discussed. New mandibular third molar impaction and extraction difficulty degree classification based on anatomical and radiologic findings and literature review results was proposed. Conclusions: The classification proposed here based on anatomical and radiological impacted mandibular third molar features is promising to be a helpful tool for impacted tooth assessment as well as for planning for surgical operation. Further clinical studies should be conducted for new classification validation and reliability evaluation.

  9. Radiographic Evaluation of Root and Canal Morphologies of Third Molar Teeth in Iranian Population

    Directory of Open Access Journals (Sweden)

    Faramarzi

    2013-06-01

    Full Text Available Background Root and canal morphology of teeth has a significant role in endodontic treatment success. Third molars have strategic roles after losing first and second molars. Objectives This study investigated the morphology of permanent third molar using radiography in Dentistry University of Hamadan during 2011. Materials and Methods In this experimental study, 352 extracted molars (179 maxillary and 173 mandibular molars were collected. After preparing access cavity and file placement in canals, to investigate the number of roots, canals and canal type periapical radiographies were taken from two directions (mesiodistal and buccolingual. The results were analyzed using SPSS version 16.0 software and descriptive statistics. Results According to the study on 173 mandibular third molars, 92.4%, 4.6%, and 2.89% had two, one, and three roots, respectively. Majority of them had two or three canals and most of mesial root canals were type 2; but in 179 maxillary third molars, findings showed that 67.6%, 15%, 11.7%, and 5.6% of teeth had three, one, two, and four roots, respectively, majority of which had three canals (68.7%. Canals of 100% of distobuccal and palatal roots and 91% of mesiobuccal roots were type 1. Conclusions However, root and canal anatomies of third molar teeth are unknown, but studies focusing on third molar teeth have shown their possibility of treatment.

  10. An unusual occurrence of bilaterally geminated mandibular second premolars resulting in premolar molarization: A case report

    Directory of Open Access Journals (Sweden)

    A V Rajesh Ebenezar

    2013-01-01

    Full Text Available Gemination refers to an attempt by a single tooth bud to divide, with a resultant formation of either a large tooth with a bifid crown or two completely divided teeth throughout the crown and root. This report describes a rare case of bilateral gemination of permanent mandibular second premolar tooth giving rise to molarization of premolars. The mesiodistal width of these teeth is similar to mandibular molars, but the cervicoocclusal width is lesser than that of the molar tooth. This paper also discusses the potential orthodontic, periodontal, and endodontic complications of premolar molarization.

  11. Shape reconstruction from apparent contours theory and algorithms

    CERN Document Server

    Bellettini, Giovanni; Paolini, Maurizio

    2015-01-01

    Motivated by a variational model concerning the depth of the objects in a picture and the problem of hidden and illusory contours, this book investigates one of the central problems of computer vision: the topological and algorithmic reconstruction of a smooth three dimensional scene starting from the visible part of an apparent contour. The authors focus their attention on the manipulation of apparent contours using a finite set of elementary moves, which correspond to diffeomorphic deformations of three dimensional scenes. A large part of the book is devoted to the algorithmic part, with implementations, experiments, and computed examples. The book is intended also as a user's guide to the software code appcontour, written for the manipulation of apparent contours and their invariants. This book is addressed to theoretical and applied scientists working in the field of mathematical models of image segmentation.

  12. Prevalence of upper airway obstruction in patients with apparently asymptomatic euthyroid multi nodular goitre

    Directory of Open Access Journals (Sweden)

    Sunil K Menon

    2011-01-01

    Full Text Available Aims: To study the prevalence of upper airway obstruction (UAO in "apparently asymptomatic" patients with euthyroid multinodular goitre (MNG and find correlation between clinical features, UAO on pulmonary function test (PFT and tracheal narrowing on computerised tomography (CT. Materials and Methods: Consecutive patients with apparently asymptomatic euthyroid MNG attending thyroid clinic in a tertiary centre underwent clinical examination to elicit features of UAO, PFT, and CT of neck and chest. Statistical Analysis Used: Statistical analysis was done with SPSS version 11.5 using paired t-test, Chi square test, and Fisher′s exact test. P value of <0.05 was considered to be significant. Results: Fifty-six patients (52 females and four males were studied. The prevalence of UAO (PFT and significant tracheal narrowing (CT was 14.3%. and 9.3%, respectively. Clinical features failed to predict UAO or significant tracheal narrowing. Tracheal narrowing (CT did not correlate with UAO (PFT. Volume of goitre significantly correlated with degree of tracheal narrowing. Conclusions: Clinical features do not predict UAO on PFT or tracheal narrowing on CT in apparently asymptomatic patients with euthyroid MNG.

  13. The uptake of manganese ions and the apparent thermal transition of the erythrocyte membranes.

    Science.gov (United States)

    Morariu, V V; Ionescu, M S; Frangopol, M; Grosescu, R; Lupu, M; Frangopol, P T

    1986-08-01

    The nuclear magnetic resonance manganese doping technique is currently used for the determination of the water diffusional exchange time through human erythrocyte membranes. An apparent thermal transition at 26 degrees C was noticed at 18-30 mM manganese doping in the suspending solution. An analysis in terms of a two-phase nuclear spin exchanging system revealed that apparent thermal transitions are expected to occur in the upper and lower temperature regions. They represent a shift from intermediate exchange rates where water diffusion through the membrane is dominant to either fast or slow exchange rates where proton relaxation is the controlling process. The lower temperature apparent transition may be altered by the intracellular manganese concentration; the lower the Mn2+ concentration the lower the transition. Also according to this interpretation only a fraction of the erythrocytes are significantly permeated by Mn2+. The upper transition depends on the Mn2+ concentration in the extracellular volume; it decreases with decreasing Mn2+ concentration.

  14. Changes in membrane lipid composition of Mycoplasma capricolum affect the cell volume.

    OpenAIRE

    N. Romano; Shirvan, M H; Rottem, S.

    1986-01-01

    The cellular water volume of Mycoplasma capricolum was markedly increased by a decrease in the cholesterol-to-phospholipid molar ratio in the membrane. An increase in cell volume was also observed with the increase in the phospholipid cell membrane content obtained by the incorporation of exogenous phosphatidylcholine from the growth medium.

  15. Foliation dependence of black hole apparent horizons in spherical symmetry

    CERN Document Server

    Faraoni, Valerio; Firouzjaee, Javad T; Helou, Alexis; Musco, Ilia

    2016-01-01

    Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation-dependent. We expose the problem and discuss possible solutions using the Hawking quasilocal mass. In spherical symmetry, we present a physically sensible approach to the problem by restricting to spherically symmetric spacetime slicings. In spherical symmetry the apparent horizons are gauge-independent in any spherically symmetric foliation but physical quantities associated with them, such as surface gravity and temperature, are not. The widely used comoving and Kodama foliations, which are of particular interest, are discussed in detail.

  16. Enhancement of apparent resistance to ethanol in Lactobacillus hilgardii

    OpenAIRE

    Couto, José António; Pina, Cristina; Hogg, Tim

    1997-01-01

    The survival of Lactobacillus hilgardii, a highly ethanol-tolerant organism, after an ethanol challenge at 25% (v/v) for 10 min, increased by several log cycles when cells, grown in the absence of ethanol, were pre-treated with 10% (v/v) ethanol, 15% (v/v) methanol or 2% (v/v) butanol for 4 h. A temperature upshift (25 to 40°C) before ethanol challenge demonstrated a similar enhancement of apparent resistance to ethanol. Ethanol shock enhanced apparent resistance to methanol, butanol and heat...

  17. Influence of magnesia-to-phosphate molar ratio on microstructures, mechanical properties and thermal conductivity of magnesium potassium phosphate cement paste with large water-to-solid ratio

    International Nuclear Information System (INIS)

    This paper describes the influence of the magnesia-to-phosphate (M/P) molar ratios ranging from 4 to 12, on the properties and microstructures of magnesium potassium phosphate cement (MKPC) pastes with a large water-to-solid ratio (w/s) of 0.50. The setting behavior, compressive strength, tensile bonding strength and thermal conductivity of the MKPC pastes, were investigated. The results show that an increase in the M/P ratio can slow down the setting reaction, and clearly degrade the mechanical strengths, but clearly improve the thermal conductivity of MKPC pastes. Furthermore, micro-characterizations including X-ray diffraction, scanning electron microscopy and thermogravimetric analysis, on the MKPC pastes reveal that a lower M/P ratio can facilitate better crystallization of the resultant magnesium potassium phosphate hexahydrate (MKP) and a denser microstructure. Moreover, strong linear correlations are found between the mechanical strengths and the MKP-to-space ratio, and between thermal conductivity and the volume ratio of the unreacted magnesia to the MKP. - Highlights: • Increase of M/P molar ratio causes clear mechanical degradations on MKPC pastes. • Thermal conductivity of MKPC pastes is improved with increase of M/P molar ratio. • Lower M/P ratio leads to better MKP crystallization and denser microstructure. • Strengths of MKPC pastes are linearly correlated to the MKP-to-space ratios. • Thermal conductivity is affected by the volume ratio of unreacted magnesia to MKP

  18. Detection of Mesiobuccal Canal in Maxillary Molars and Distolingual Canal in Mandibular Molars by Dental CT: A Retrospective Study of 100 Cases

    Directory of Open Access Journals (Sweden)

    Sushma Rathi

    2010-01-01

    Full Text Available Objective. To detect presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars by Dental CT. Material and Methods. A retrospective study of 100 Dental CTs was done. Axial and paraxial images obtained were used to assess the presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars. Results. The youngest patient was of 11 years while the eldest patient was of 77 years. Males were 58 in number and females were 42 in number. MB2 canals were present in 57 patients and distolingual canal was present in 18 patients. Maximum MB2 canals were present in age group between 51 and 60 years, while distolingual canals were present in age group of 21–30 years. Conclusion. Dental CT allows adequate visualization of variation in root canal morphology and can be important diagnostic tool for successful endodontic therapy.

  19. Forced extrusion for removal of impacted third molars close to the mandibular canal Extrusión forzada para extraer los terceros molares impactados cerca del canal mandibular

    OpenAIRE

    Dennis Flanagan DDS

    2012-01-01

    Impacted mandibular third molars can be located in close proximity to the mandibular canal. This creates a risk for the nerve or artery injury. These are contained in the canal. However, the impacted third molar can be moved coronally by orthodontic means, after removal of overlying bone, and safely extracted. The orthodontic intervention slowly moves the tooth apex away from the mandibular canal and reduces the potential for a neural injury. This method may be useful for older patients with ...

  20. A extração de segundos molares superiores para o tratamento da Classe II Extraction of upper second molars for treatment of Angle Class II malocclusion

    Directory of Open Access Journals (Sweden)

    Maurício Barbieri Mezomo

    2010-06-01

    Full Text Available Este trabalho tem por objetivo apresentar uma abordagem alternativa para o tratamento ortodôntico das más oclusões de Classe II. Através de uma revisão da literatura, verificou-se que a extração de segundos molares superiores demonstrou ser uma alternativa viável para o tratamento desse tipo de má oclusão. Essa opção terapêutica possibilita maior rapidez na distalização dos primeiros molares com menor necessidade de cooperação por parte do paciente. Porém, a análise do grau de formação, posição intraóssea e morfologia do terceiro molar deve ser cuidadosamente realizada para proporcionar o correto posicionamento do mesmo no lugar do segundo molar extraído. Dois casos clínicos apresentarão a sequência do diagnóstico e tratamento com essa mecânica, exibindo resultados adequados dos pontos de vista funcional e estético.The purpose of this article is to present an alternative approach to the orthodontic treatment of Angle Class II malocclusion. According to a literature review it was observed that the extraction of upper second molars has proven to be a viable alternative for the treatment of this type of malocclusion. This therapeutic option enables faster first molar retraction and requires less patient compliance. However, the level of development, intraosseous position and morphology of the third molar should be carefully evaluated to ensure its correct positioning in place of the extracted second molar. Two clinical case reports will demonstrate that the sequence of diagnosis and treatment used with this mechanics yields satisfactory functional and aesthetic results.

  1. A modified device for intraoral radiography to assess the distal osseous defects of mandibular second molar after impacted third molar surgery

    OpenAIRE

    Ana, Faria-Inocencio; Mercedes, Gallas-Torreira

    2011-01-01

    Purpose This article is to describe a modified device for intraoral radiography which was developed to obtain reproducible radiographic images for assessment of distal osseous defects of the mandibular second molar (2 Mm) after impacted third molar (3 Mm) surgery. Materials and Methods A commercial available alignment system for posterior region was modified by adding a reference gauge pin (millimetric) and threading a hollow acrylic cylinder at the ring of the radiographic positioner to atta...

  2. Mesomorphic phase behaviour of low molar mass PEP-PDMS diblock copolymers synthesized by anionic polymerization

    International Nuclear Information System (INIS)

    The phase behaviour of low molar mass poly(ethylene-alt-propylene) -poly(dimethylsiloxane) (PEP-PDMS) is investigated in this thesis by the combination of dynamical mechanical spectroscopy (rheology) to measure phase transition temperatures, and small-angle x-ray scattering to identify the morphology of encountered phases. Samples of PEP-PDMS in the range of 0.2-0.7 in volume fraction of PEP are studied. This diblock copolymer system exhibits the three classical phases of lamellar sandwich structure (LAM), hexagonally packed cylinders (HEX), and spheres arranged on a body centered cubic lattice (BCC). Furthermore the gyroid phase (Ia3d symmetry) of two interpenetrating networks was also identified as a stable phase of the PEP-PDMS system. Time resolved measurements of small-angle neutron scattering in tandem with simultaneous in-situ rheological measurements are performed on samples showing transitions between different ordered phases. The identification of especially the BCC and gyroid phases from scattering experiments is treated. By performing mesoscopic crystallographic measurements using a custom built goniometer it was unambiguously shown that the application of shear to an unoriented powder-like sample introduces uniaxial orientation of the gyroid phase. The orientation of the ordered phase is otherwise random, causing a two-dimensional powder. Finally this dissertation presents a discussion of relevant parameters for the description of diblock copolymer phase behaviour together with descriptions of anionic polymerization for the synthesis of copolymers, and various experimental techniques for the characterization of diblocks. (au)

  3. Appearance of dentin gamma-carboxyglutamic acid-containing proteins in developing rat molars in vitro

    International Nuclear Information System (INIS)

    An in vitro model of mineralization was devised in order to study the developmental appearance of dentin gamma-carboxyglutamic acid-containing proteins (DGPs) in relation to the onset of mineralization. Maxillary third molars from 11-day-old rats were cultured with or without fetal calf serum (FCS) as modified from Navia et al. Molars were incubated without radiolabel, or with either 45CaCl2 (5 microCi/ml) for 24 hr at various stages of a ten-day culture period or [3H]-leucine (10 microCi/ml) for 24 hr at the eighth day of culture. Molars were lyophilized and extracted with 10% formic acid overnight at 4 degrees C. DGPs in extracts were detected by immunologic and chromatographic techniques; DGPs in molar sections were detected by immunolocalization using indirect immunofluorescence. Molar development was evaluated histologically using the Von Kossa staining technique. Molars cultured with FCS showed histologic evidence for mineralized dentin and enamel and a significant increase in 45Ca uptake after the sixth day in vitro. Eleven-day-old molars in vivo and molars cultured without FCS showed no evidence of the presence of mineralized tissues. [3H]-Leucine-labeled DGPs were isolated and identified by affinity and reversed-phase high-performance liquid chromatography and by gel electrophoresis from both mineralized and unmineralized molars. DGP antigens were localized immunohistochemically using rabbit anti-rat antibodies raised against a highly purified DGP preparation. In the unmineralized molar, antigenicity was seen in odontoblasts but not in predentin matrix, preodontoblasts, or in any other cell type. Antigens in the mineralized molar were localized to odontoblasts and dentin

  4. Children with fever without apparent source: diagnosis and dilemmas

    NARCIS (Netherlands)

    S.E. Bleeker (Sacha)

    2002-01-01

    textabstractTills thesis describes the results of diagnostic research in young children presenting with fever without apparent source at the emergency department. The study was conducted at the Sophia Children's University Hospital in Rotterdam and the Juliana Children's Hospital in The Hague, both

  5. Studying the cosmological apparent horizon with quasistatic coordinates

    Indian Academy of Sciences (India)

    Rui-Yan Yu; Towe Wang

    2013-02-01

    This article aims at a natural generalization of the static coordinates to the ( + 1)-dimensional Friedmann–Lemaître–Robertson–Walker (FLRW) Universe. After demonstrating a no-go theorem, we put forward the quasistatic coordinates for the FLRW Universe. Then, the quasistatic coordinates are utilized to study the unified first law and the scalar-type perturbations on the cosmological apparent horizon.

  6. A New Theory of Leadership: "Realwert" Versus Apparent Good.

    Science.gov (United States)

    Lang, Donald

    1999-01-01

    "Realwert" ("real good") stems from an understanding of humanity's "raison d'etre"--treating others with respect and dignity. It can be contrasted with "apparent good," a condition wherein one mistakenly thinks real good is being pursued. Drawing on Aquinas and Hodginson, this paper argues for a "realwert" conception of educational leadership. (63…

  7. An Apparent Paradox: Catt's Anomaly

    Science.gov (United States)

    Pieraccini, M.; Selleri, S.

    2013-01-01

    Catt's anomaly is a sort of "thought experiment" (a "gedankenexperiment") where electrons seem to travel at the speed of light. Although its author argued with conviction for many years, it has a clear and satisfactory solution and it can be considered indubitably just an apparent paradox. Nevertheless, it is curious and…

  8. On the apparent horizon in fluid-gravity duality

    NARCIS (Netherlands)

    I. Booth; M.P. Heller; G. Plewa; M. Spalinski

    2011-01-01

    This article develops a computational framework for determining the location of boundary-covariant apparent horizons in the geometry of conformal fluid-gravity duality in arbitrary dimensions. In particular, it is shown up to second order and conjectured to hold to all orders in the gradient expansi

  9. Apparent mineralocorticoid excess: time of manifestation and complications despite treatment

    NARCIS (Netherlands)

    Knops, N.B.; Monnens, L.A.H.; Lenders, J.W.M.; Levtchenko, E.N.

    2011-01-01

    Here we describe the case of a patient followed from birth because of a positive family history for apparent mineralocorticoid excess (AME) in an older brother. The patient, a girl, had normal serum electrolyte and blood pressure measurements in the first months after birth. Not until the age of 11

  10. Apparent Barrier Height in Scanning Tunneling Microscopy Revisited

    DEFF Research Database (Denmark)

    Olesen, L.; Brandbyge, Mads; Sørensen, Mads Reinholdt;

    1996-01-01

    The apparent barrier height phi(ap), that is, the rate of change of the logarithm of the conductance with tip-sample separation in a scanning tunneling microscope (STM), has been measured for Ni, Pt, and Au single crystal surfaces. The results show that phi(ap) is constant until point contact...

  11. Discovery of an Apparent Nova in M81

    Science.gov (United States)

    Hornoch, K.; Alfaro, M. Diaz; Ordonez-Etxeberria, I.; Vaduvescu, O.

    2015-01-01

    We report the discovery of an apparent nova in M81 on a co-added 1600-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~2.4" seeing on 2015 Jan. 15.126 UT.

  12. Phosphorus release from anaerobic peat soil during convective discharge – effect of soil Fe:P molar ratio and preferential flow

    DEFF Research Database (Denmark)

    Forsmann, Ditte M.; Kjærgaard, Charlotte

    2014-01-01

    –66 μmol kg− 1 day− 1) were negatively non-linearly correlated with the soil FeBD:PBD molar ratio, which explained 71–73% of the variability, and with FeBD:PBD of 10 as a critical threshold ratio. Fe and P release rates from batch experiments were poorly correlated with convective discharge Fe and P...... was controlled by reductive Fe(III) dissolution, and was well predicted from the soil FeBD:PBD molar ratio. Continuous convective column discharge with oxygen-free deionised water at 1 mm h− 1 for 10 effluent pore volumes resulted in highly variable in situ redox potential (Eh from − 200 to 300 mV), effluent Fe......(II) concentrations (23 to 2000 μM) and effluent dissolved reactive phosphorus (DRP) concentrations (convective discharge (3...

  13. Effects of liquid morphology and distribution on the apparent properties of porous media made of stacked particles

    Directory of Open Access Journals (Sweden)

    Mingzhi Yu

    2015-05-01

    Full Text Available To understand the effects of liquid morphology on the apparent transfer properties of porous media formed by stacked particles, the authors investigate the particles’ aggregation state, apparent volume, thermal conductivity, and electrical conductivity of wet stacked glass beads. It shows that the liquid mainly exists as liquid bridges when the liquid content is low and connects each other when high. The transformation of liquid morphology and distribution influences the liquid effects on particles, thus changing the aggregation state of the particles and the apparent properties of the porous media in turn. A model is developed for predicting the critical liquid content at which the liquid morphology shifts from the state of liquid bridges into the state of interconnectedness. The prediction from the model is in good agreement with the experiment.

  14. Evaluation of telemedicine systems for impacted third molars diagnosis

    Directory of Open Access Journals (Sweden)

    Duka Miloš

    2009-01-01

    Full Text Available Background/Aim. In the last twenty years significant advances have been made in the fields of information and telecommunication technology in health care applications, with a positive impact on the health care practice. The need for remote diagnosis and planning of interventions is of special importance in military health care, and health management of immobile persons, and those with special needs. In cases such as these, availability of specialist health care is mainly limited by geographic and financial factors. The aim of this study was to investigate practical usability of telemedicine approaches in everyday management of oral surgery patients in terms of reliability of established diagnosis and indications for oral surgery treatment of the third molars. Methods. Our experimental randomized study enrolled 432 randomly selected patients of both genders, aged 20 to 87 years, undergoing panoramic radiography for some reason in the Centre for Dental Radiography in Belgrade. In addition to radiography, photographs of the face and mouth cavity were taken. These images were uploaded to the web server specially dedicated to the study purposes, and then transmitted to teledentists, i.e. oral surgeons, who made remote diagnoses. Diagnostic agreement was determined by way of the Cohen's kappa coefficient, and diagnostic sensitivity (SE, specificity (SP, and effectiveness (EFF were also established. Statistical significance was determined and comparisons performed by using the z-test, and testing of non-parametric characteristics by using the McNemar's χ2 test for p = 0.05 significance cut-off. Results. The results obtained by analyzed images and diagnostic assessment of the clinical diagnosis (kappa = 0.99, SE = 99%, SP = 99%, EFF = 99%, for 95% CI indicate an almost complete diagnostic agreement. The differences in diagnosis were not statistically significant. Conclusion. Diagnostic assessment of the clinical diagnosis of impacted or semi

  15. Modified distal shoe appliance for premature loss of multiple deciduous molars: a case report.

    Science.gov (United States)

    Bhat, Prasanna Kumar; K, Navin H; Idris, Mohammed; Christopher, Pradeep; Rai, Niharika

    2014-08-01

    Preservation of the primary dentition until the normal time of exfoliation is one of the most important factor involved in preventive and interceptive dentistry. The premature loss of second primary molar before the eruption of permanent first molar can create a significant arch space/tooth size discrepancy. Distal shoe space maintainer is a valuable part of the Paediatric Dentist's armamentarium in those cases where the second primary molar is prematurely lost and it helps to guide the first permanent molar into place. Conventional design poses various limitations in cases of premature loss of multiple deciduous molars. Thus, it is required to modify the conventional designs according to the needs of the patient. This case report describes an innovative modification of distal shoe appliance in cases of premature loss of multiple deciduous molars. In the present case, modification of distal shoe space maintainer was advocated because of inadequate abutments caused due to multiple loss of deciduous molars. Bilateral design of distal shoe was planned for unilateral loss of deciduous molars.

  16. Radiological age estimation: based on third molar mineralization and eruption in Turkish children and young adults.

    Science.gov (United States)

    Karadayi, Beytullah; Kaya, Ahsen; Kolusayın, Melek Ozlem; Karadayi, Sükriye; Afsin, Hüseyin; Ozaslan, Abdi

    2012-11-01

    Radiographic evaluation of mineralization and eruption stages of third molars using dental panoramic radiographies can be an efficient tool for chronological age estimation in both forensic sciences and legal medicine. The third molar tooth is utilized for dental age estimation about the age span of 15-23 years because it represents the only tooth still in development. The aim of this study is to obtain and analyze data regarding third molar development and eruption in Turkish population for dental age estimation. A total of 744 dental panoramic radiographies of 394 female and 350 male subjects aged between 8 and 22 years were examined. Third molar development was determined according to the Nolla classification system, and eruption was assessed relative to the alveolar bone level. Mandibular and maxillary third molars were generally found at similar stages of development on both sides. Nolla stage 6 (completed crown calcification) was reached at around the age of 15 in both maxillary and mandibular third molars in both sexes. Alveolar emergence was at around the age of 16 in males and around age of 17 in females. Although third molars' eruption shows greater variability than development of third molars, data which were obtained from this study about eruption of these teeth can be supportive to development data for age estimation.

  17. Micro-CT analyses of apical enlargement and molar root canal complexity

    DEFF Research Database (Denmark)

    Markvart, Merete; Darvann, Tron Andre; Larsen, Per;

    2012-01-01

    AIM: To compare the effectiveness of two rotary hybrid instrumentation techniques with focus on apical enlargement in molar teeth and to quantify and visualize spatial details of instrumentation efficacy in root canals of different complexity. METHODOLOGY: Maxillary and mandibular molar teeth were...

  18. Molar mass of poly(ethylene terephthalate) (PET) during ultimate uniaxial drawing

    NARCIS (Netherlands)

    Göschel, U.; Cools, P.J.C.H.

    2000-01-01

    The changes of the average molar mass Mw, Mn, Mz, and molar mass distributions during multistep uniaxial drawing of poly(ethylene terephthalate) (PET) to achieve ultimate mechanical properties have been studied in detail by means of size exclusion chromatography (SEC) with triple detection: concentr

  19. Hypomineralized second primary molars: Prevalence data in Dutch 5-year-olds

    NARCIS (Netherlands)

    Elfrink, M.E.C.; Schuller, A.A.; Weerheijm, K.L.; Veerkamp, J.S.J.

    2008-01-01

    The aim of this cross-sectional observational study was to report on the prevalence of hypomineralizations in second primary molars in 5-year-old Dutch children. In the study 386 (45% girls) 5-year-old Dutch children, all insured by a Health Insurance Fund, participated. Scoring criteria for molar i

  20. Functional approach to a Class II patient with upper first molar impaction

    Directory of Open Access Journals (Sweden)

    Giacomo D′Orlandi

    2014-01-01

    Full Text Available The lack of the left first molar maxillary and the left second molar maxillary, caused respectively by impaction and agenesis is a very rare case, which determines an important occlusal imbalance and asymmetrical mandible movement. A gnatologic and functional orthodontic approach were planned to improve the retrognathic mandible and the muscular activity using kinesiograph and electromyography.

  1. Validity of scoring caries and primary molar hypomineralization (DMH) on intraoral photographs

    NARCIS (Netherlands)

    M.E.C. Elfrink; J.S.J. Veerkamp; I.H.A. Aartman; H.A. Moll; J.M. ten Cate

    2009-01-01

    AIM: The aims of this study were to assess whether intraoral photographs could be used to score caries and hypomineralization on primary molars (Using adapted Molar Incisor Hypomineralization (MIH)-criteria), and also to assess the reliability and validity in 3-7 year-old Dutch children of these sco

  2. A New Anatomically Based Nomenclature for the Roots and Root Canals—Part 1: Maxillary Molars

    Directory of Open Access Journals (Sweden)

    Jojo Kottoor

    2012-01-01

    Full Text Available Numerous terminologies have been employed in the dental literature to describe the roots and root canal systems of maxillary molars. This multiplicity in naming of roots and canals makes the reader susceptible to misinterpretation and confusion. No consensus thus far has been arrived at for defining the names of roots and root canals in maxillary molars, including their various morphological aberrations. The anatomical relation of roots and their root canals were identified and were subsequently named based on definite sets of criteria. A new method for identification and naming of roots and root canal anatomy in maxillary molars, based on their root and canal relationship, was formulated and is presented in this paper. The nomenclature makes certain essential modifications to the traditional approach to accommodate naming of the various aberrations presented in the maxillary molars. A simple, yet extensive, nomenclature system has been proposed that appropriately names the internal and external morphology of maxillary molars.

  3. Prevalence of Third Molar Agenesis: Associated Dental Anomalies in Non-Syndromic 5923 Patients.

    Science.gov (United States)

    Sujon, Mamun Khan; Alam, Mohammad Khursheed; Rahman, Shaifulizan Abdul

    2016-01-01

    The aim of this study was to investigate the prevalence of third molar agenesis and other associated dental anomalies in Bangladeshi population and to investigate the relationship of other dental anomalies with the third molar presence/agenesis. A retrospective study was performed using panoramic radiographs of 5923 patients, who ranged in age from 10 to 50 years. All radiographs were analyzed by Planmeca Romexis® 3.0 software (Planmeca Oy, Helsinki, Finland). Pearson chi-square and one way ANOVA (Post Hoc) test were conducted. The prevalence of third molar agenesis was 38.4%. The frequency of third molar agenesis was significantly higher in females than males (p dental anomalies was 6.5%, among them hypodontia was 3.1%. Prevalence of third molar agenesis varies in different geographic region. Among the other dental anomalies hypodontia was more prevalent. PMID:27580050

  4. Biodentine Pulpotomy in Mature Permanent Molar: A Case Report

    Science.gov (United States)

    2016-01-01

    Irreversible pulpitis is the most common reason for endodontic treatment in primary and permanent teeth. Root canal therapy and extraction are the two viable and most documented treatment options for the same. Studies with regards to management of mature permanent teeth with carious exposure and treatment with vital pulp therapies such as adult permanent tooth pulpotomy are scarce. However, permanent tooth pulpotomy with the new calcium-silicate based cements (Mineral Trioxide Aggregate and Biodentine) can help preserve the tooth pulp vitality and promote healing and repair foregoing the more invasive root canal therapy procedure. A 12-year old male patient with irreversible pulpitis in right mandibular first permanent molar was treated with complete coronal pulpotomy with placement of Biodentine in the pulp chamber and a full coronal coverage using stainless steel crown. Clinical and radiographic examinations were performed at three, six, twelve and eighteen months. At the end of 18 months, the patient was completely asymptomatic and the tooth was free of any clinical and radiographic signs of inflammation and infection. PMID:27630966

  5. Molar crown inner structural organization in Javanese Homo erectus.

    Science.gov (United States)

    Zanolli, Clément

    2015-01-01

    This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans. In accordance with their outer occlusal morphology, the specimens exhibit a set of derived internal features, such as thick to hyperthick enamel, an incomplete expression of the crest patterns at the enamel-dentine junction (EDJ) level, a sharp EDJ topography. As a whole, these features differ from those expressed in some penecontemporaneous specimens/samples representing African H. erectus/ergaster and H. heidelbergensis, as well as in Neanderthals, but occur in recent human populations. Further research in virtual dental paleoanthropology to be developed at macroregional scale would clarify the polarity and intensity of the intermittent exchanges between continental and insular Southeast Asia around the Lower to Middle Pleistocene boundary, as well as should shed light on the still poorly understood longitudinal evolutionary dynamics across continental Asia. PMID:25209431

  6. Dietary inference from upper and lower molar morphology in platyrrhine primates.

    Directory of Open Access Journals (Sweden)

    Kari L Allen

    Full Text Available The correlation between diet and dental topography is of importance to paleontologists seeking to diagnose ecological adaptations in extinct taxa. Although the subject is well represented in the literature, few studies directly compare methods or evaluate dietary signals conveyed by both upper and lower molars. Here, we address this gap in our knowledge by comparing the efficacy of three measures of functional morphology for classifying an ecologically diverse sample of thirteen medium- to large-bodied platyrrhines by diet category (e.g., folivore, frugivore, hard object feeder. We used Shearing Quotient (SQ, an index derived from linear measurements of molar cutting edges and two indices of crown surface topography, Occlusal Relief (OR and Relief Index (RFI. Using SQ, OR, and RFI, individuals were then classified by dietary category using Discriminate Function Analysis. Both upper and lower molar variables produce high classification rates in assigning individuals to diet categories, but lower molars are consistently more successful. SQs yield the highest classification rates. RFI and OR generally perform above chance. Upper molar RFI has a success rate below the level of chance. Adding molar length enhances the discriminatory power for all variables. We conclude that upper molar SQs are useful for dietary reconstruction, especially when combined with body size information. Additionally, we find that among our sample of platyrrhines, SQ remains the strongest predictor of diet, while RFI is less useful at signaling dietary differences in absence of body size information. The study demonstrates new ways for inferring the diets of extinct platyrrhine primates when both upper and lower molars are available, or, for taxa known only from upper molars. The techniques are useful in reconstructing diet in stem representatives of anthropoid clade, who share key aspects of molar morphology with extant platyrrhines.

  7. Apparent Dissolution Kinetics of Diatomite in Alkaline Solution

    Institute of Scientific and Technical Information of China (English)

    DU Gaoxiang; L(U) Guocheng; HE Xuwen

    2013-01-01

    The dissolution kinetics of diatomite in alkaline solution is the theoretical basis for the process optimization of alkali-diatomite reaction and its applications.In this study,the dissolution kinetics of diatomite in NaOH solution is investigated.The results indicate that the dissolution reaction fits well the unreacted shrinking core model for solid-liquid heterogeneous reactions.The apparent reaction order for NaOH is 2 and the apparent activation energy for the reaction (Ea) is 28.06 kJ.mol-1.The intra-particle diffusion through the sodium silicate layer is the rate-controlling step.When the dissolution reaction occurs at the interface of unreacted diatomite solid core,the diffusion in the trans-layer (the liquid film around the wetted particle) reduces the rate of whole dissolution process.

  8. Crystalloids in apparent autophagic plastids: remnants of plastids or peroxisomes?

    Science.gov (United States)

    Papini, Alessio; van Doorn, Wouter G

    2015-02-01

    Plant macroautophagy is carried out by autophagosome-type organelles. Recent evidence suggests that plastids also can carry out macroautophagy. The double membrane at the surface of plastids apparently invaginates, forming an intraplastidial space. This space contains a portion of cytoplasm that apparently becomes degraded. Here we report, in Tillandsia sp. and Aechmaea sp., the presence of almost square or diamond-shaped crystalloids inside what seems the intraplastidial space of autophagous plastids. The same type of crystalloids were observed in chloroplasts and other plastids, but were not found in the cytoplasm or the vacuole. Peroxisomes contained smaller and more irregularly shaped crystalloids compared to the ones observed in 'autophagous' plastids. It is hypothesized that plastids are able to sequester chloroplasts and other plastids. PMID:25462964

  9. The Apparent and Intrinsic Shape of the APM Galaxy Clusters

    CERN Document Server

    Basilakos, S; Manolis, P; Basilakos, Spyros; Maddox, Steve; Plionis, Manolis

    2000-01-01

    We estimate the distribution of intrinsic shapes of APM galaxy clusters fromthe distribution of their apparent shapes. We measure the projected clusterellipticities using two alternative methods. The first method is based onmoments of the discrete galaxy distribution while the second is based onmoments of the smoothed galaxy distribution. We study the performance of bothmethods using Monte Carlo cluster simulations covering the range of APM clusterdistances and including a random distribution of background galaxies. We findthat the first method suffers from severe systematic biases, whereas the secondis more reliable. After excluding clusters dominated by substructure andquantifying the systematic biases in our estimated shape parameters, we recovera corrected distribution of projected ellipticities. We use the non-parametrickernel method to estimate the smooth apparent ellipticity distribution, andnumerically invert a set of integral equations to recover the correspondingdistribution of intrinsic ellipticiti...

  10. Apparent Viscosity of Active Nematics in Poiseuille Flow

    Science.gov (United States)

    Cui, Zhenlu; Su, Jianbing; Zeng, Xiaoming

    2015-09-01

    A Leslie-Erickson continuum hydrodynamic for flowing active nematics has been used to characterize active particle systems such as bacterial suspensions. The behavior of such a system under a plane pressure-driven Poiseuille flow is analyzed. When plate anchoring is tangential and normal, we find the apparent viscosity formula indicating a significant difference between tangential anchoring and normal anchoring conditions for both active rodlike and discoid nematics.

  11. Definition of apparent activation energy on DTG curves

    Directory of Open Access Journals (Sweden)

    A. K. Serikbayeva

    2016-07-01

    Full Text Available The article gives the results of sulphidation oxidized copper ores and tailings with sulfur. Defined by the apparent activation energy in the conditions of heating the mixture of substances interacting with a constant speed by differential thermogravimetry (DTG. It was established that the sulfiding may occur in a kinetic mode , since the interaction is charged, in the presence of liquid and gaseous sulfur , i.e. transport of sulfur to the surface of the mineral is not a limiting process.

  12. Definition of apparent activation energy on DTG curves

    OpenAIRE

    Serikbayeva, A. K.; Zhumashev, K.; N. Sh. Janaliyeva; M. Rakhimberdina

    2016-01-01

    The article gives the results of sulphidation oxidized copper ores and tailings with sulfur. Defined by the apparent activation energy in the conditions of heating the mixture of substances interacting with a constant speed by differential thermogravimetry (DTG). It was established that the sulfiding may occur in a kinetic mode , since the interaction is charged, in the presence of liquid and gaseous sulfur , i.e. transport of sulfur to the surface of the mineral is not a limiting process.

  13. Apparent disapperance of hypernatraemic dehydration from infant deaths in Sheffield.

    Science.gov (United States)

    Sunderland, R; Emery, J L

    1979-09-01

    The death certificates and necropsy reports of the 1115 Sheffield infants who died under 2 years of age in 1969-78 were examined. This study showed the apparent disappearance of deaths with hypernatraemia and in particular deaths presenting as cot deaths. The fall in incidence may be as much the result of an intensive local campaign on child care and infant feeding as of the change in the composition of dried milk for baby feeding.

  14. Information Limits on Identification of Natural Surfaces by Apparent Colour

    OpenAIRE

    Foster, David H.; Nascimento, Sérgio M. C.; Amano, Kinjiro

    2005-01-01

    By adaptational and other mechanisms, the visual system can compensate for moderate changes in the colour of the illumination on a scene. Although the colours of most surfaces are perceived to be constant (“colour constancy”), some are not. The effect of these residual colour changes on the ability of observers to identify surfaces by their apparent colour was determined theoretically from high-resolution hyperspectral images of natural scenes under different daylights with correlated colour ...

  15. Lead-Free Metamaterials with Enormous Apparent Piezoelectric Response.

    Science.gov (United States)

    Zhou, Wanfeng; Chen, Pan; Pan, Qi; Zhang, Xiaotong; Chu, Baojin

    2015-11-01

    Lead-free flexoelectric piezoelectric metamaterials are created by applying an asymmetric chemical reduction to Na1/2 Bi1/2 TiO3 -BaTiO3 ceramics. The reduction induces two gradient-generating mechanisms, curvature structure and chemical inhomogeneity, and enhances the flexoelectric effect. The ceramics behave like piezoelectric materials, exhibiting an enormous and high-temperature stable apparent piezoelectric response, outperforming existing lead-oxide-based piezoelectrics.

  16. Infants' perception of subjective contours from apparent motion.

    Science.gov (United States)

    Yamaguchi, Masami K; Kanazawa, So; Okamura, Hiromi

    2008-01-01

    We examined infants' perception of subjective contours in Subjective-Contour-from-Apparent-Motion (SCAM) stimuli [e.g., Cicerone, C. M., Hoffman, D. D., Gowdy, P. D., & Kim, J. S. (1995). The perception of color from motion. Perception & Psychophysics, 57, 761-777] using the preferential looking technique. The SCAM stimulus is composed of random dots which are assigned two different colors. Circular region assigned one color moved apparently, keeping all dots' location unchanged. In the SCAM stimulus, adults can perceive subjective color spreading and subjective contours in apparent motion (http://c-faculty.chuo-u.ac.jp/ approximately ymasa/okamura/ibd_demo.html). In the present study, we conducted two experiments by using this type of SCAM stimulus. A total of thirty-six 3-8-month-olds participated. In experiment 1, we presented two stimuli to the infants side by side: a SCAM stimulus consisting of different luminance, and a non-SCAM stimulus consisting of isoluminance dots. The results indicated that the 5-8-month-olds showed preference for the SCAM stimuli. In experiments 2 and 3, we confirmed that the infants' preference for the SCAM stimulus was not generated by the local difference and local change made by luminance of dots but by the subjective contours. These results suggest that 5-8-month-olds were able to perceive subjective contours in the SCAM stimuli. PMID:17727955

  17. The apparent state of droplets on a rough surface

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The factors influencing the state and wetting transition of droplets on a rough surface are both complex and obscure. The change in wetting is directly reflected by changes under the contact condition of the droplets with the surface. The recent study about the wettability of the superhydrophobic surface under the condensing condition arouses the new understanding about the apparent state of droplets on a rough surface. In this work, to validate the existence of droplets in an intermediate state, a microscale pillar topological polydimethylsiloxane (PDMS) surface was manufactured and its wettability under various conditions was studied. According to the experimental data, it is proposed that the wetting state of a rough surface may be embodied using the contact area ratio of a solid/liquid/gas droplet with the projective plane. A general calculation model for the apparent contact angle of droplets is given and expressed diagrammatically. It is found that the measured apparent contact angles of droplets at dif- ferent states on the surface falls within the range predicted by our proposed equation.

  18. Apparent directional spectral emissivity determination of semitransparent materials

    Science.gov (United States)

    Chun-Yang, Niu; Hong, Qi; Ya-Tao, Ren; Li-Ming, Ruan

    2016-04-01

    An inverse estimation method and corresponding measurement system are developed to measure the apparent spectral directional emissivities of semitransparent materials. The normal spectral emissivity and transmissivity serve as input for the inverse analysis. Consequently, the refractive index and absorption coefficient of the semitransparent material could be retrieved by using the pseudo source adding method as the forward method and the stochastic particle swarm optimization algorithm as the inverse method. Finally, the arbitrary apparent spectral directional emissivity of semitransparent material is estimated by using the pseudo source adding method given the retrieval refractive index and absorption coefficient. The present system has the advantage of a simple experimental structure, high accuracy, and excellent capability to measure the emissivity in an arbitrary direction. Furthermore, the apparent spectral directional emissivity of sapphire at 773 K is measured by using this system in a spectral range of 3 μm–12 μm and a viewing range of 0°–90°. The present method paves the way for a new directional spectral emissivity measurement strategy. Project supported by the National Natural Science Foundation of China (Grant Nos. 51476043 and 51576053) and the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51421063).

  19. Coherent and random apparent stresses in periodically unsteady flows

    Science.gov (United States)

    Kehoe, Anthony Byrd

    1990-08-01

    The transitional flow field downstream of a smooth, symmetrically constricted Sylgard pipe was measured with a two color, two component Laser Doppler Anemometer for both pulsatile and steady flows. Vibrations in the flow system were induced with an exciter/shaker and were monitored with an accelerator. The vibration has little effect on the value of the maximum axial and radial turbulence intensities. A frequency domain signal processing technique to separate the disturbance velocity into coherent and random components was modified to guarantee that the sum of the decomposed velocity components equaled the original disturbance velocity. Results of the velocity separation demonstrated that the velocity disturbances prior to turbulent transition consisted almost entirely of coherent velocity fluctuations. The maximum apparent shear stress was found to occur just after the turbulent transition and consisted almost entirely of the random component. The data suggest that if the absolute magnitude of the apparent stress is the determining factor in red blood cell destruction, then the coherent apparent stress is not a significant destruction mechanism. However, the exact mechanism in hemolysis are not identified.

  20. Physiologic Basis for Improved Pulmonary Function after Lung Volume Reduction

    OpenAIRE

    Fessler, Henry E.; Scharf, Steven M; Ingenito, Edward P.; McKenna, Robert J.; Sharafkhaneh, Amir

    2008-01-01

    It is not readily apparent how pulmonary function could be improved by resecting portions of the lung in patients with emphysema. In emphysema, elevation in residual volume relative to total lung capacity reduces forced expiratory volumes, increases inspiratory effort, and impairs inspiratory muscle mechanics. Lung volume reduction surgery (LVRS) better matches the size of the lungs to the size of the thorax containing them. This restores forced expiratory volumes and the mechanical advantage...

  1. Pulpal responses to cavity preparation in aged rat molars.

    Science.gov (United States)

    Kawagishi, Eriko; Nakakura-Ohshima, Kuniko; Nomura, Shuichi; Ohshima, Hayato

    2006-10-01

    The dentin-pulp complex is capable of repair after tooth injuries including dental procedures. However, few data are available concerning aged changes in pulpal reactions to such injuries. The present study aimed to clarify the capability of defense in aged pulp by investigating the responses of odontoblasts and cells positive for class II major histocompatibility complex (MHC) to cavity preparation in aged rat molars (300-360 days) and by comparing the results with those in young adult rats (100 days). In untreated control teeth, immunoreactivity for intense heat-shock protein (HSP)-25 and nestin was found in odontoblasts, whereas class-II-MHC-positive cells were densely distributed in the periphery of the pulp. Cavity preparation caused two types of pulpal reactions based on the different extent of damage in the aged rats. In the case of severe damage, destruction of the odontoblast layer was conspicuous at the affected site. By 12 h after cavity preparation, numerous class-II-MHC-positive cells appeared along the pulp-dentin border but subsequently disappeared together with HSP-25-immunopositive cells, and finally newly differentiated odontoblast-like cells took the place of the degenerated odontoblasts and acquired immunoreactivity for HSP-25 and nestin by postoperative day 3. In the case of mild damage, no remarkable changes occurred in odontoblasts after operation, and some survived through the experimental stages. These findings indicate that aged pulp tissue still possesses a defense capacity, and that a variety of reactions can occur depending on the difference in the status of dentinal tubules and/or odontoblast processes in individuals.

  2. Prevalence and features of distolingual roots in mandibular molars analyzed by cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Mi Ree; Moon, Young Mi; Seo, Min Seock [Dept. of Conservative Dentistry, Wonkang University Daejeon Dental Hospital, Daejeon (Korea, Republic of)

    2015-12-15

    This study evaluated the prevalence of distolingual roots in mandibular molars among Koreans, the root canal system associated with distolingual roots, and the concurrent appearance of a distolingual root in the mandibular first molar and a C-shaped canal in the mandibular second molar. Cone-beam computed tomographic images of 264 patients were screened and examined. Axial sections of 1056 mandibular molars were evaluated to determine the number of roots. The interorifice distances from the distolingual canal to the distobuccal canal were also estimated. Using an image analysis program, the root canal curvature was calculated. Pearson's chi-square test, the paired t-test, one-way analysis of variance, and post-hoc analysis were performed. Distolingual roots were observed in 26.1% of the subjects. In cases where a distolingual root was observed in the mandibular molar, a significant difference was observed in the root canal curvature between the buccolingual and mesiodistal orientations. The maximum root canal curvature was most commonly observed in the mesiodistal orientation in the coronal portion, but in the apical portion, maximum root canal curvature was most often observed in the buccolingual orientation. The canal curvature of distolingual roots was found to be very complex, with a different direction in each portion. No correlation was found between the presence of a distolingual root in the mandibular first molar and the presence of a C-shaped canal in the mandibular second molar.

  3. Evaluation of the distortion rate of panoramic and peri apical radiographs in erupted third molar inclination

    International Nuclear Information System (INIS)

    Panoramic and peri apical radiographs are normally used in impacted third molar teeth surgeries. The aim of the present study was to evaluate and compare the distortion of the erupted third molar teeth on panoramic and peri apical radiographs. Patients and Methods: A total of 44 radiographs were obtained of 22 patients (age range, 18-24 years) referred to the faculty of dentistry for orthodontic treatment. A plaster cast was prepared and panoramic radiography was taken for all patients to plan the orthodontic treatment and peri apical radiography was taken for investigation of tooth structure details. Therefore, a total of 66 views and samples were studied by two methods: 1) Measuring the angle between the longitudinal plane of the third molar and occlusal plane. 2) Measuring the angle between the longitudinal plane of second and third molar. Finally, 132 records were evaluated by one individual. Results: There was no significant statistical difference between the mean position of the third molar on panoramic, peri apical radiographs and the casts. However, measurements of the third molars on peri apical radiographs were slightly closer to the measurements of the casts compared to the panoramic radiographs. Conclusion: Distortion does not have a specific effect on the diagnosis of the position of the third erupted molars by peri apical or panoramic radiographs, though various studies have shown that these radiographs have an amount of distortion and peri apical radiographical distortion is less than that in panoramic radiography.

  4. Morphometric variation of extant platyrrhine molars: taxonomic implications for fossil platyrrhines.

    Science.gov (United States)

    Nova Delgado, Mónica; Galbany, Jordi; Pérez-Pérez, Alejandro

    2016-01-01

    The phylogenetic position of many fossil platyrrhines with respect to extant ones is not yet clear. Two main hypotheses have been proposed: the layered or successive radiations hypothesis suggests that Patagonian fossils are Middle Miocene stem platyrrhines lacking modern descendants, whereas the long lineage hypothesis argues for an evolutionary continuity of all fossil platyrrhines with the extant ones. Our geometric morphometric analysis of a 15 landmark-based configuration of platyrrhines' first and second lower molars suggest that morphological stasis may explain the reduced molar shape variation observed. Platyrrhine lower molar shape might be a primitive retention of the ancestral state affected by strong ecological constraints throughout the radiation of the main platyrrhine families. The Patagonian fossil specimens showed two distinct morphological patterns of lower molars, Callicebus-like and Saguinus-like, which might be the precursors of the extant forms, whereas the Middle Miocene specimens, though showing morphological resemblances with the Patagonian fossils, also displayed new, derived molar patterns, Alouatta-like and Pitheciinae-like, thereby suggesting that despite the overall morphological stasis of molars, phenotypic diversification of molar shape was already settled during the Middle Miocene. PMID:27190704

  5. Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars

    Science.gov (United States)

    Abarca, J.; Zaror, C.; Monardes, H.; Hermosilla, V.; Muñoz, C.; Cantin, M.

    2015-01-01

    SUMMARY Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3–5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24–0.33 mm in maxillary first molars and between 0.25–0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully. PMID:25937698

  6. Radiographic findings on 3rd molars removed in 20-year-old men.

    Science.gov (United States)

    Rajasuo, Ari; Peltola, Jaakko; Ventä, Irja; Murtomaa, Heikki

    2003-10-01

    In this study we assess radiographic findings characteristic of mandibular 3rd molars that had required either routine or surgical extraction. X-ray findings relating to acute pericoronitis were also examined. The material was collected by investigating patient records and rotational panoramic radiographs of 20-year-old Finnish male conscripts (n = 738) treated during military service because of 3rd-molar-related problems. The follicle around the crown of mandibular 3rd molars with acute pericoronitis was enlarged in 19% of cases and in 13% of chronic symptom-free pericoronitis cases (not statistically significant difference). Mandibular 3rd molars extracted surgically were more often mesially inclined than those extracted routinely (61% vs. 23%; P pericoronitis [around 27% vs. 39% of the teeth routinely extracted (OR 0.5, 95% CI 0.3-0.8)]. In 86% of cases the space between 2nd molar and ramus of the mandible was narrower than the 3rd molar extracted surgically, whereas this was 62% in routine extraction cases (P < 0.001). We conclude that there are some typical 3rd-molar findings in rotational panoramic radiographs that show a need for surgical extraction.

  7. Radiographic correlation of dental and skeletal age: Third molar, an age indicator

    Directory of Open Access Journals (Sweden)

    G N Suma

    2011-01-01

    Full Text Available Background: Age estimation plays a great role in forensic investigations, orthodontic and surgical treatment planning, and tooth transplantation. Teeth offer an excellent material for age determination by stages of development below the age of 25 years and by secondary changes after the age of 25 years. Third molar is often not included for this purpose due to its notorious developmental patterns. The aim of this study was to evaluate the development of third molar anlage in relation to skeletal maturities and the chronological age. Materials and Methods: One hundred and fifty-six young individuals, 78 males and 78 females, were selected. The stages of development of all the third molars in every individual were determined from panoramic radiographs. The skeletal development was assessed using hand wrist radiographs. Data were analyzed statistically for mean value, standard deviation and the relationship between the recorded characteristics. Results: A strong correlation was found between third molar development and skeletal maturity (in males: r=0.88, P<0.001; in females: r=0.77 for maxillary third molar and 0.89 for mandibular third molar, P<0.001. Conclusion: Hence, it is concluded that a strong correlation exists between chronological age, developmental stages of third molars and maturation of epiphyses of hand. Any of the three parameters could be used for the assessment of other maturities.

  8. Sex determination in modern Greeks using diagonal measurements of molar teeth.

    Science.gov (United States)

    Zorba, Eleni; Moraitis, Konstantinos; Eliopoulos, Constantine; Spiliopoulou, Chara

    2012-04-10

    Sex determination is a necessary step in the investigation of unidentified human remains from a forensic context. Teeth, as one of the strongest tissues in the human body, can be used for this purpose. Most studies of sexual dimorphism in teeth are based on the traditional mesiodistal and buccolingual crown measurements. The purpose of this study is to examine the degree of sexual dimorphism in permanent molars of modern Greeks using crown and cervical diagonal diameters, and to evaluate their applicability in sex determination. A total of 344 permanent molars in 107 individuals (53 male and 54 female) from the Athens Collection were examined. Crown and cervical diagonal diameters of both maxillary and mandibular molars were measured. It was found that males have larger molars than females and in 19 out of 24 dimensions measured male molars exceeded female molars significantly (Pdiagonal diameters have found to be more sexually diamorphic than crown diagonal diameters. In discriminant function analysis the variables entered more frequently were the cervical diagonal diameters mainly of mandibular molars. Classification accuracy was found to be 93% for the total sample, 77.4% for upper jaw, and 88.4% for the lower jaw. Accuracy rates were higher for cervical than crown diagonal diameters. The data generated from the present study suggest that this metric method can be useful and reliable for sex determination, especially when the traditional dental measurements are not applicable.

  9. Development of the first permanent mandibular molar in young children with unilateral complete cleft lip and palate (UCCLP)

    DEFF Research Database (Denmark)

    Hermann, Nuno Vibe; Darvann, Tron A; Kreiborg, Sven

    Development of the first permanent mandibular molar in young children with unilateral complete cleft lip and palate (UCCLP)......Development of the first permanent mandibular molar in young children with unilateral complete cleft lip and palate (UCCLP)...

  10. Allometric and metameric shape variation in Pan mandibular molars: a digital morphometric analysis.

    Science.gov (United States)

    Singleton, Michelle; Rosenberger, Alfred L; Robinson, Chris; O'neill, Rob

    2011-02-01

    The predominance of molar teeth in fossil hominin assemblages makes the patterning of molar shape variation a topic of bioanthropological interest. Extant models are the principal basis for understanding dental variation in the fossil record. As the sister taxon to the hominin clade, Pan is one such model and the only widely accepted extant hominid model for both interspecific and intraspecific variation. To explore the contributions of allometric scaling and meristic variation to molar variation in Pan, we applied geometric shape analysis to 3D landmarks collected from virtual replicas of chimpanzee and bonobo mandibular molars. Multivariate statistical analysis and 3D visualization of metameric and allometric shape vectors were used to characterize shape differences and test the hypothesis that species of Pan share patterns of metameric variation and molar shape allometry. Procrustes-based shape variables were found to effectively characterize crown shape, sorting molars into species and tooth-row positions with ≥ 95% accuracy. Chimpanzees and bonobos share a common pattern of M(1) -M(2) metameric variation, which is defined by differences in the relative position of the metaconid, size of the hypoconulid, curvature of the buccal wall, and proportions of the basins and foveae. Allometric scaling of molar shape is homogeneous for M(1) and M(2) within species, but bonobo and chimpanzee allometric vectors are significantly different. Nevertheless, the common allometric shape trend explains most molar-shape differences between P. paniscus and P. troglodytes. When allometric effects are factored out, chimpanzee and bonobo molars are not morphometrically distinguishable. Implications for hominid taxonomy and dietary reconstruction are discussed. PMID:21235007

  11. Developmental constraints revealed by co-variation within and among molar rows in two murine rodents.

    Science.gov (United States)

    Renaud, Sabrina; Pantalacci, Sophie; Quéré, Jean-Pierre; Laudet, Vincent; Auffray, Jean-Christophe

    2009-01-01

    Morphological integration corresponds to interdependency between characters that can arise from several causes. Proximal causes of integration include that different phenotypic features may share common genetic sets and/or interact during their development. Ultimate causes may be the prolonged effect of selection favoring integration of functionally interacting characters, achieved by the molding of these proximal causes. Strong and direct interactions among successive teeth of a molar row are predicted by genetic and developmental evidences. Functional constraints related to occlusion, however, should have selected more strongly for a morphological integration of occluding teeth and a corresponding evolution of the underlying developmental and genetic pathways. To investigate how these predictions match the patterns of phenotypic integration, we studied the co-variation among the six molars of the murine molar row, focusing on two populations of house mice (Mus musculus domesticus) and wood mice (Apodemus sylvaticus). The size and shape of the three upper and lower molars were quantified and compared. Our results evidenced similar patterns in both species, size being more integrated than shape among all the teeth, and both size and shape co-varying strongly between adjacent teeth, but also between occluding teeth. Strong co-variation within each molar row is in agreement with developmental models showing a cascade influence of the first molar on the subsequent molars. In contrast, the strong co-variation between molars of the occluding tooth rows confirms that functional constraints molded patterns of integration and probably the underlying developmental pathways despite the low level of direct developmental interactions occurring among molar rows. These patterns of co-variation are furthermore conserved between the house mouse and the wood mouse that diverged >10 Ma, suggesting that they may constitute long-running constraints to the diversification of the murine

  12. Lattice potential energy and standard molar enthalpy in the formation of 1-dodecylamine hydrobromide(1-C12H25NH3·Br)(s)

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-Pu; Di You-Ying; Dan Wen-Yan; He Dong-Hua; Kong Yu-Xia; Yang Wei-Wei

    2011-01-01

    This paper reports that 1-dodecylamine hydrobromide (1-C12H25NH3·Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3·Br and the ionic volume and radius of the 1-C12H25NH3+ cation are obtained from the crystallographic data and other auxiliary ther-modynamic data. The constant-volume energy of combustion of 1-C12H25NH3·Br(s) is measured to be △cUm°(1-C12H25NH3·Br, s) =-(7369.03±3.28) kJ·mol-1 by means of an RBC-Ⅱ precision rotating-bomb combustion calorimeter at T=(298.15±0.001) K. The standard molar enthalpy of combustion of the compound is derived to be △cHm°(1-C12H25NH3·Br, s)=-(7384.52±3.28) kJ·mol-1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be △fHm°(1-C12H25NH3·Br, s)=-(1317.86±3.67) kJ·mol-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.

  13. Mandibular third molars and anterior crowding in the lower jaw. A longitudinal study from 15 to 21 years

    OpenAIRE

    2009-01-01

    The aim of the study is to examine whether presence of third molars contribute to changes in anterior dental alignment in the lower jaw in individuals from adolescence to young adulthood, when compared to the development in individuals with congenitally missing third molars. Our study suggests that mandibular third molar is not a contributing factor to crowding in mandibular alignment. A greater reduction in intercanine width occured when mandibular third molars were missing when compa...

  14. Dental caries characteristics in the first permanent molar in school age children. Comportamiento de la caries dental en el primer molar permanente en escolares.

    Directory of Open Access Journals (Sweden)

    Ana Gloria Vázquez de León

    2009-04-01

    Full Text Available Background: Dental caries is one of the main health problems in children. The first permanent molar presents caries more frequently than any other. Objective: To describe the characteristics of dental caries in the first permanent molars in children between 6 and 13 years-old, and to assess oral hygiene and knowledge about the subject in all the patients treated in the stomatology consultation Barrio adentro “El Guapo”, from November 2005 to March 2006. Methods: A descriptive, transversal study showed that most of the patients had dental caries. It was proved that many of them had, at least, on of the first molars affected by dental caries. The quotient first molar affected/ patient was higher than one. Results: There was a decrease in the percentage of healthy permanent first molars. Poor oral hygiene prevailed, with a medium knowledge level on the subject. Most of the parents didn´t know about the first molar dental cavity. Conclusions: It was needed to perform educative tasks aimed at this age group to avoid further damage to this important tooth, central for the development of the stomatognathic system.Fundamento: La caries dental continúa siendo el principal problema de salud de la población infantil. El diente

  15. A New Orthodontic Appliance with a Mini Screw for Upper Molar Distalization

    Science.gov (United States)

    2016-01-01

    The aim of this study is to present a new upper molar distalization appliance called Cise distalizer designed as intraoral device supported with orthodontic mini screw for upper permanent molar distalization. The new appliance consists of eight main components. In order to understand the optimum force level, the appliance under static loading is tested by using strain gage measurement techniques. Results show that one of the open coils produces approximately 300 gr distalization force. Cise distalizer can provide totally 600 gr distalization force. This range of force level is enough for distalization of upper first and second molar teeth. PMID:27528796

  16. Unusual facial pain secondary to inferior alveolar nerve compression caused by impacted mandibular second molar

    Directory of Open Access Journals (Sweden)

    Urvashi Sharma

    2014-01-01

    Full Text Available Symptoms of inferior alveolar nerve (IAN compression are reported during endodontic procedures, placement of implants, third molar surgeries, inferior alveolar nerve block injections, trauma, orthognathic injuries, ablative surgeries or use of medicaments. Presented is a rare case of a 15-year-old girl who reported severe pain in relation to an impacted permanent mandibular left second molar, the roots of which had entrapped the mandibular canal causing compression of IAN. Timely surgical intervention and sectional removal of the impacted molar is indicated to relieve the symptoms and avoid permanent damage to the nerve.

  17. A New Anatomically Based Nomenclature for the Roots and Root Canals—Part 2: Mandibular Molars

    Directory of Open Access Journals (Sweden)

    Denzil Valerian Albuquerque

    2012-01-01

    Full Text Available Several terminologies have been employed in the dental literature to describe the roots and root canal systems of mandibular molars with no consensus being arrived at, thus far. The anatomical relation of roots and their root canals were identified and a naming system was formulated. The proposed nomenclature attempts to make certain essential modifications to the traditional approach to accommodate the naming of various aberrations presented in mandibular molars. A simple, yet extensive nomenclature system has been proposed that appropriately names the internal and external morphology of mandibular molars.

  18. Morphological and anthropological aspects of human triangular deciduous lower first molar teeth.

    Science.gov (United States)

    Kitagawa, Y; Manabe, Y; Oyamada, J; Rokutanda, A

    1996-04-01

    The crown and root morphology, and bilateral occurrence of human deciduous lower first molars that exhibited a triangular occlusal outline, taken from excavated samples of Japanese, Jomonese and Iraqi origin, were investigated. The crowns of triangular teeth had smaller mesiodistal and larger buccolingual diameters than normally shaped deciduous lower first molars. An elongated buccolingual diameter was derived from the buccal projection of the distobuccal cusp and lingual projection of the portion between the metaconid and distolingual cusp. In this analysis, all triangular deciduous lower first molars in which root morphology could be observed were accompanied by additional distolingual roots. Correlation between the right- and left-hand sides of this trait was high.

  19. Initial tooth movement under extraoral force and considerations for controlled molar movement.

    Science.gov (United States)

    Yoshida, N; Jost-Brinkmann, P G; Yamada, Y

    1995-01-01

    Initial movement of the maxillary first molars under the application of straight-pull, cervical-pull, and high-pull headgear was measured in human subjects. Facebow deflection can influence molar movement as the relationship of the force vector to the molar's center of resistance changes with an increase of force. The present study proposes using headgear with a combination of variable-pull headcap and short outer bow. A variable-pull headcap allows a great range in force direction. The direction of the headgear force system can be accurately determined using a short outer bow.

  20. Investigation of High Molar Ratio Potassium Solution Used in Zinc-Rich Coatings

    Institute of Scientific and Technical Information of China (English)

    LI Sheng; WU Hang; YAN Rui

    2004-01-01

    High molar ratio potassium silicate solution used in zinc-rich water-base coatings was prepared by adding the nanosize SiO2 to the low molar ratio potassium silicate solution, and its microstructure was investigated by SEM and IR.Furthermore, the zinc-rich coatings was prepared by adding the zinc powders to this type of solution, and the properties of the coatings were evaluated. The test results show that the high molar ratio potassium silicate solution is the bonder of zinc-rich inorganic coatings with excellent property.

  1. Volume of ionic sites in silicate glasses

    International Nuclear Information System (INIS)

    Molar volume data of alkali and alkaline earth silicate glasses have been used to calculate the free volume associated with the bridging and nonbridging oxygen and modifier ions. The free volume associated with the bridging oxygen is constant (15.39 x 10-24 cm3) for all modifier ions up to 33.3 mol% modifier oxide. It decreases (in alkali or alkaline earth silicate glasses) with increasing number of nonbridging oxygen ions per structural unit and/or radius of the modifier ion. The nonbridging oxygen ion is associated with a constant free volume (6.50 x 10-24 cm3) in all cases. Modifier ions are associated with free volume that increases with increasing number of nonbridging oxygen ions per structural unit and/or radius of the modifier ion. The used model explores the change in the free volume due to changing the concentration of alkali oxides in mixed alkali silicate glasses. The results show that, in such glasses, the free volume related to a certain type of alkali oxide increases with increasing content

  2. Ultrasonic backscatter from cancellous bone: the apparent backscatter transfer function.

    Science.gov (United States)

    Hoffmeister, Brent K; Mcpherson, Joseph A; Smathers, Morgan R; Spinolo, P Luke; Sellers, Mark E

    2015-12-01

    Ultrasonic backscatter techniques are being developed to detect changes in cancellous bone caused by osteoporosis. Many techniques are based on measurements of the apparent backscatter transfer function (ABTF), which represents the backscattered power from bone corrected for the frequency response of the measurement system. The ABTF is determined from a portion of the backscatter signal selected by an analysis gate of width τw delayed by an amount τd from the start of the signal. The goal of this study was to characterize the ABTF for a wide range of gate delays (1 μs ≤ τd ≤ 6 μs) and gate widths (1 μs ≤ τw ≤ 6 μs). Measurements were performed on 29 specimens of human cancellous bone in the frequency range 1.5 to 6.0 MHz using a broadband 5-MHz transducer. The ABTF was found to be an approximately linear function of frequency for most choices of τd and τw. Changes in τd and τw caused the frequency-averaged ABTF [quantified by apparent integrated backscatter (AIB)] and the frequency dependence of the ABTF [quantified by frequency slope of apparent backscatter (FSAB)] to change by as much as 24.6 dB and 6.7 dB/MHz, respectively. τd strongly influenced the measured values of AIB and FSAB and the correlation of AIB with bone density (-0.95 ≤ R ≤ +0.68). The correlation of FSAB with bone density was influenced less strongly by τd (-0.97 ≤ R ≤ -0.87). τw had a weaker influence than τd on the measured values of AIB and FSAB and the correlation of these parameters with bone density.

  3. Effectiveness of various sterilization methods of contaminated post-fitted molar band

    Directory of Open Access Journals (Sweden)

    Anggia Tridianti

    2013-06-01

    Full Text Available Background: Molar band as anchoring device may be contaminated during the fitting process. Thus, decontamination process is essential to prevent cross-infection between patients. Purpose: The objective of this research was to determine the amount of bacteria in molar band post-fitted on the patient teeth, after previously undergone pre-sterilization using alcohol and ultrasonic cleaning bath followed by sterilization using dry heat oven and steam autoclave, in order to find the best method in decontamination of post-fitted molar band. Methods: Four molar bands which already fitted on one patient then divided evenly into two groups. The first group was pre-sterilized using alcohol. One of the bands then sterilized using dry heat oven, while the other one was sterilized using steam autoclave. The second group was pre-sterilized using ultrasonic cleaning bath. One band from this group then sterilized using dry heat oven and the other was sterilized using steam autoclave. The next step was to immerse all the bands in a phosphate-buffered saline solution. Using micropipette, the solution was retrieved and dropped upon a petri dish containing Brain Heart Infusion broth. The dish was then stored in an incubator for 24 hours, prior to counting the number of bacteria existed. The same methods were used to the rest of the patients, with total 128 molar bands from 32 patients. Results: There was a profound difference in numbers of bacteria found between those methods of sterilization. However, there was a non significant difference between the two groups which were at the alcohol-steam autoclave group and at the ultrasonic cleaning bath-steam autoclave group. Conclusion: This study showed that steam autoclave is better than for sterilizing molar band, as it left the minimal amount of bacteria in post-fitted molar band.Latar belakang: Molar band merupakan suatu alat penjangkaran yang dapat mengalami kontaminasi selama proses fitting band, sehingga perlu

  4. Endodontic treatment of a mandibular second molar with four roots – A case report and literature review

    Directory of Open Access Journals (Sweden)

    Jorge N.R. Martins

    2014-06-01

    Conclusions: A configuration with four roots is rare for the mandibular molars. This configuration has an incidence of 0.04% in the first lower molar with only three in vivo case reports available. For the second lower molar, no incidence ratio was found.

  5. A discrete model for the apparent viscosity of polydisperse suspensions including maximum packing fraction

    CERN Document Server

    Dörr, Aaron; Mehdizadeh, Amirfarhang

    2012-01-01

    Based on the notion of a construction process consisting of the stepwise addition of particles to the pure fluid, a discrete model for the apparent viscosity as well as for the maximum packing fraction of polydisperse suspensions of spherical, non-colloidal particles is derived. The model connects the approaches by Bruggeman and Farris and is valid for large size ratios of consecutive particle classes during the construction process. Furthermore, a new general form of the well-known Krieger equation allowing for the choice of a second-order Taylor coefficient for the volume fraction is proposed and then applied as a monodisperse reference equation in the course of polydisperse modeling. By applying the polydisperse viscosity model to two different particle size distributions (Rosin-Rammler and uniform distribution), the influence of polydispersity on the apparent viscosity is examined. The extension of the model to the case of small size ratios as well as to the inclusion of shear rate effects is left for fut...

  6. Mechanical Components from Highly Recoverable, Low Apparent Modulus Materials

    Science.gov (United States)

    Padula, Santo, II (Inventor); Noebe, Ronald D. (Inventor); Stanford, Malcolm K. (Inventor); DellaCorte, Christopher (Inventor)

    2015-01-01

    A material for use as a mechanical component is formed of a superelastic intermetallic material having a low apparent modulus and a high hardness. The superelastic intermetallic material is conditioned to be dimensionally stable, devoid of any shape memory effect and have a stable superelastic response without irrecoverable deformation while exhibiting strains of at least 3%. The method of conditioning the superelastic intermetallic material is described. Another embodiment relates to lightweight materials known as ordered intermetallics that perform well in sliding wear applications using conventional liquid lubricants and are therefore suitable for resilient, high performance mechanical components such as gears and bearings.

  7. Discovery of an Apparent Nova in M81

    Science.gov (United States)

    Hornoch, K.; Vaduvescu, O.; Gonzalez, A.

    2013-04-01

    We report the discovery of an apparent nova in the M81 galaxy on a co-added 2000-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma in ~1.4" seeing on Apr. 5.946 UT. The new object is visible on individual 400-s frames and well visible on the co-added image (see the finding chart linked below), but is not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 21.7.

  8. Downscaling Smooth Tomographic Models: Separating Intrinsic and Apparent Anisotropy

    Science.gov (United States)

    Bodin, Thomas; Capdeville, Yann; Romanowicz, Barbara

    2016-04-01

    In recent years, a number of tomographic models based on full waveform inversion have been published. Due to computational constraints, the fitted waveforms are low pass filtered, which results in an inability to map features smaller than half the shortest wavelength. However, these tomographic images are not a simple spatial average of the true model, but rather an effective, apparent, or equivalent model that provides a similar 'long-wave' data fit. For example, it can be shown that a series of horizontal isotropic layers will be seen by a 'long wave' as a smooth anisotropic medium. In this way, the observed anisotropy in tomographic models is a combination of intrinsic anisotropy produced by lattice-preferred orientation (LPO) of minerals, and apparent anisotropy resulting from the incapacity of mapping discontinuities. Interpretations of observed anisotropy (e.g. in terms of mantle flow) requires therefore the separation of its intrinsic and apparent components. The "up-scaling" relations that link elastic properties of a rapidly varying medium to elastic properties of the effective medium as seen by long waves are strongly non-linear and their inverse highly non-unique. That is, a smooth homogenized effective model is equivalent to a large number of models with discontinuities. In the 1D case, Capdeville et al (GJI, 2013) recently showed that a tomographic model which results from the inversion of low pass filtered waveforms is an homogenized model, i.e. the same as the model computed by upscaling the true model. Here we propose a stochastic method to sample the ensemble of layered models equivalent to a given tomographic profile. We use a transdimensional formulation where the number of layers is variable. Furthermore, each layer may be either isotropic (1 parameter) or intrinsically anisotropic (2 parameters). The parsimonious character of the Bayesian inversion gives preference to models with the least number of parameters (i.e. least number of layers, and

  9. Discovery of Two Apparent Novae in M81

    Science.gov (United States)

    Hornoch, K.; McCormac, J.; Vaduvescu, O.

    2013-06-01

    We report the discovery of two apparent novae in the M81 galaxy on a co-added 1600-s, narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma in ~1.5" seeing on 2013 June 3.905 UT. The new objects are visible on individual 400-s frames and well visible on the co-added image (see the finding chart linked below), but are not present on numerous narrow-band H-alpha archival images from the INT down to a limiting magnitude as faint as H-alpha = 22.7.

  10. Discovery of Three Apparent Novae in M81

    Science.gov (United States)

    Hornoch, K.; Vaduvescu, O.; Oers, P. van

    2013-02-01

    We report the discovery of three apparent novae in the M81 galaxy on a co-added 3200-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma in ~1.4" seeing on Feb. 25.132 UT. The new objects are visible on individual 400-s frames and well visible on the co-added image (see the finding chart linked below), but are not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 22.5.

  11. Reduced central blood volume in cirrhosis

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik; Bendtsen, Flemming; Sørensen, T I;

    1989-01-01

    was inversely correlated to the systemic vascular resistance (r = -0.49, p less than 0.001), the latter being significantly reduced in the patient group. Patients with cirrhosis apparently are unable to maintain a normal central blood volume. This may be due to arteriolar vasodilation, portosystemic collateral......The pathogenesis of ascites formation in cirrhosis is uncertain. It is still under debate whether the effective blood volume is reduced (underfilling theory) or whether the intravascular compartment is expanded (overflow theory). This problem has not yet been solved because of insufficient tools...... for measuring the central blood volume. We have developed a method that enables us to determine directly the central blood volume, i.e., the blood volume in the heart cavities, lungs, and central arterial tree. In 60 patients with cirrhosis and 16 control subjects the central blood volume was assessed according...

  12. Mesomorphic phase behaviour of low molar mass PEP-PDMS diblock copolymers synthesized by anionic polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Vigild, M.E.

    1997-10-01

    The phase behaviour of low molar mass poly(ethylene-alt-propylene) -poly(dimethylsiloxane) (PEP-PDMS) is investigated in this thesis by the combination of dynamical mechanical spectroscopy (rheology) to measure phase transition temperatures, and small-angle x-ray scattering to identify the morphology of encountered phases. Samples of PEP-PDMS in the range of 0.2-0.7 in volume fraction of PEP are studied. This diblock copolymer system exhibits the three classical phases of lamellar sandwich structure (LAM), hexagonally packed cylinders (HEX), and spheres arranged on a body centered cubic lattice (BCC). Furthermore the gyroid phase (Ia3d symmetry) of two interpenetrating networks was also identified as a stable phase of the PEP-PDMS system. Time resolved measurements of small-angle neutron scattering in tandem with simultaneous in-situ rheological measurements are performed on samples showing transitions between different ordered phases. The identification of especially the BCC and gyroid phases from scattering experiments is treated. By performing mesoscopic crystallographic measurements using a custom built goniometer it was unambiguously shown that the application of shear to an unoriented powder-like sample introduces uniaxial orientation of the gyroid phase. The orientation of the ordered phase is otherwise random, causing a two-dimensional powder. Finally this dissertation presents a discussion of relevant parameters for the description of diblock copolymer phase behaviour together with descriptions of anionic polymerization for the synthesis of copolymers, and various experimental techniques for the characterization of diblocks. (au). 9 tabs., 40 ills., 81 refs.

  13. Apparent diffusion coefficient correlation with oesophageal tumour stroma and angiogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Aoyagi, Tomoyoshi; Shuto, Kiyohiko; Okazumi, Shinichi; Hayano, Kohichi; Satoh, Asami; Saitoh, Hiroshige; Shimada, Hideaki; Nabeya, Yoshihiro; Matsubara, Hisahiro [Chiba University, Department of Frontier Surgery, Graduate School of Medicine, Chiba (Japan); Kazama, Toshiki [Chiba University, Department of Radiology, Graduate School of Medicine, Chiba (Japan)

    2012-06-15

    Because diffusion-weighted imaging (DWI) can predict the prognosis of patients with oesophageal squamous cell carcinoma (ESCC), we hypothesised that apparent diffusion coefficient (ADC) values might be correlated with the collagen content and tumour angiogenesis. The purpose of this study was to determine the correlation between ADC values of ESCC before treatment and oesophageal tumour stroma and angiogenesis. Seventeen patients with ESCC were enrolled. The ADC values were calculated from the DWI score. Seventeen patients who had undergone oesophagectomy were analysed for tumour stroma, vascular endothelial growth factor (VEGF) and CD34. Tissue collagen was stained with azocarmine and aniline blue to quantitatively analyse the extracellular matrix in cancer stroma. Tissues were stained with VEGF and CD34 to analyse the angiogenesis. The ADC values decreased with stromal collagen growth. We found a negative correlation between the tumour ADC and the amount of stromal collagen (r = -0.729, P = 0.001), i.e. the ADC values decreased with growth of VEGF. We also found a negative correlation between the ADC of the tumours and the amount of VEGF (r = 0.538, P = 0.026). Our results indicated that the ADC value may be a novel prognostic factor and contribute to the treatment of oesophageal cancer. circle Magnetic resonance apparent diffusion coefficient values inversely indicate tumour stromal collagen circle There is also negative correlation between ADCs and vascular endothelial growth factor circle ADC values may contribute to the treatment of oesophageal cancer. (orig.)

  14. The apparently normal galaxy hosts for two luminous quasars

    CERN Document Server

    Bahcall, J N; Bahcall, John N; Schneider, Donald P

    1995-01-01

    HST images (with WFPC2) of PHL~909\\ (z = 0.171) and PG~0052+251\\ (z = 0.155) show that these luminous radio-quiet quasars each occur in an apparently normal host galaxy. The host galaxy of PHL~909 is an elliptical galaxy (\\sim E4) and the host of PG~0052+251 is a spiral (\\sim~Sb). Both host galaxies are several tenths of a magnitude brighter than L^*, the characteristic Schechter luminosity of field galaxies. The images of PHL~909 and PG~0052+251, when compared with HST images of other objects in our sample of 20 luminous, small-redshift (z \\leq 0.30) quasars, show that luminous quasars occur in a variety of environments. The local environments of the luminous quasars range from luminous ellipticals, to apparently normal host galaxies, to complex systems of interacting components, to faint (and as yet undetected) hosts. The bright HII regions of the host galaxy of PG~0052+251 provide an opportunity to measure directly the metallicity of the host of a luminous quasar, to establish an upper limit to the mass of...

  15. Molar incisor hypomineralization: Considerations about treatment in a controlled longitudinal case

    Directory of Open Access Journals (Sweden)

    Daniela Cristina de Oliveira

    2015-01-01

    Full Text Available Molar incisor hypomineralization (MIH is a defect in the tooth enamel of systemic origin and may affect one or all four first permanent molars frequently associated with the permanent incisors. This case reports a 7-year-old child with severe MIH in the permanent molars associated with tooth decay and intense pain. In the first stage of treatment, therapy was performed with fluoride varnish and restoration with glass ionomer cement (GIC. After 6 years of clinical and radiographic follow-up, the restorations presented wear and fractures on the margins, indicating their replacement with composite resin. Severe cases of MIH in the early permanent molars can be treated with varnish and GIC to restore the patient′s comfort and strengthen the hypomineralized dental structures. The clinical and radiographic monitoring frequently indicated when the restoration with composite resin should be performed.

  16. Management of Chronic Hyperplastic Pulpitis in Mandibular Molars of Middle Aged Adults- A Multidisciplinary Approach

    Science.gov (United States)

    Lingeswaran, Somiya; Ari, Geetha; Thyagarajan, Ramakrishnan; Logaranjani, Anitha

    2016-01-01

    The molar tooth of children and young adults is a common site for chronic hyperplastic pulpitis (pulp polyp). It rarely occurs in middle aged adults. This condition is usually characterized by extensive involvement of the pulp, dictating the extraction of involved tooth. Extraction of permanent molars can lead to transient or permanent malocclusion, aesthetic, phonetic and functional problems. Here we report a case of pulp polyp in mandibular first molar of a 33-year-old woman that grew into the carious cavity. The aim of this case report is to describe the diagnosis of a chronic hyperplastic pulpitis involving the permanent molar as well as to describe its management in order to preserve them as a functional unit of the dentition. PMID:26894192

  17. Modified Willet′s appliance for bilateral loss of multiple deciduous molars: A case report

    Directory of Open Access Journals (Sweden)

    Dhindsa A

    2008-09-01

    Full Text Available No other factor plays a more significant role in preventive and interceptive dentistry than the preservation of deciduous dentition till its normal time of exfoliation. Premature loss of a deciduous tooth or a group of teeth might lead to wide range of implications. When the deciduous second molar is lost before the eruption of first permanent molar, intra-alveolar type of space maintainer is indicated. But in cases of bilateral loss of these teeth the conventional design generally poses a variety of problems. Thus, the conventional designs are required to be modified according to the needs of the patient. Therefore, this paper describes an entirely new design of the Willet′s appliance in cases of bilateral loss of deciduous molars before the eruption of first permanent molar.

  18. Association between third mandibular molar impaction and degree of root development in adolescents

    DEFF Research Database (Denmark)

    Lauesen, Søren Rødsgaard; Andreasen, Jens O; Gerds, Thomas Alexander;

    2013-01-01

    of the mandibular third molar region from 132 subjects (71 male and 61 female) from 15 to 20 years of age. Based on the films, 264 lower third molars were classified into an eruption and an impaction group. Root development was recorded according to a quantitative method described by Haavikko (1970......: Delayed mandibular third molar root development is associated with impaction. Radiographs taken at age 15 may predict the risk of impaction and thereby guide decision making for the orthodontist or the oral and maxillofacial surgeon.......Abstract Objective: To compare the root development and the growth rate of the mandibular third molar (M3 inf) in individuals where the M3 inf erupted vs individuals exhibiting M3 inf impaction. Materials and Methods: Serial standardized intraoral radiographs (Eggen technique) were taken annually...

  19. Predicting lower third molar eruption on panoramic radiographs after cephalometric comparison of profile and panoramic radiographs

    DEFF Research Database (Denmark)

    Begtrup, Anders; Grønastøð, Halldis Á; Christensen, Ib Jarle;

    2012-01-01

    and to find a simple and reliable method for predicting the eruption of the mandibular third molar by measurements on panoramic radiographs. The material consisted of profile and panoramic radiographs, taken before orthodontic treatment, of 30 males and 23 females (median age 22, range 18-48 years......Previous studies have suggested methods for predicting third molar tooth eruption radiographically. Still, this prediction is associated with uncertainty. The aim of the present study was to elucidate the association between cephalometric measurements on profile and panoramic radiographs...... the length from the ramus to the incisors (olr-id) showed a statistically significant correlation. By combining this length with the mesiodistal width of the lower second molar, the prediction of eruption of the lower third molar was strengthened. A new formula for calculating the probability of eruption...

  20. Third molar development: evaluation of nine tooth development registration techniques for age estimations.

    Science.gov (United States)

    Thevissen, Patrick W; Fieuws, Steffen; Willems, Guy

    2013-03-01

    Multiple third molar development registration techniques exist. Therefore the aim of this study was to detect which third molar development registration technique was most promising to use as a tool for subadult age estimation. On a collection of 1199 panoramic radiographs the development of all present third molars was registered following nine different registration techniques [Gleiser, Hunt (GH); Haavikko (HV); Demirjian (DM); Raungpaka (RA); Gustafson, Koch (GK); Harris, Nortje (HN); Kullman (KU); Moorrees (MO); Cameriere (CA)]. Regression models with age as response and the third molar registration as predictor were developed for each registration technique separately. The MO technique disclosed highest R(2) (F 51%, M 45%) and lowest root mean squared error (F 3.42 years; M 3.67 years) values, but differences with other techniques were small in magnitude. The amount of stages utilized in the explored staging techniques slightly influenced the age predictions.

  1. Accidental Displacement of Third Molar into the Sublingual Space: a Case Report

    Directory of Open Access Journals (Sweden)

    Rubens Jorge

    2014-10-01

    Full Text Available Background: Successful extraction of third molars depends on preoperative diagnosis and planning. Gold standard preoperative examinations are performed through computed tomography, decreasing risks and avoiding potential accidents. The present report highlights the value of preoperative examinations in face of accidentally displaced third molars. Methods: An 18-years-old female patient underwent a third mandibular molar extraction with a general dentist. Accidentally, the mandibular left third molar was displaced into the sublingual space, making necessary a second surgical step. The surgery was interrupted and the patient was referred to an expert in maxillofacial surgery. Results: After 21 days awaiting an asymptomatic health status, the second surgical step was successfully performed using multislice computed tomography as preoperative imaging guide. Conclusions: The present case report highlights the clinical usefulness of imaging planning and informed consents in face of legal and ethic potential complaints.

  2. Periodontal healing after impacted lower third molar surgery in adolescents and adults. A prospective study.

    Science.gov (United States)

    Kugelberg, C F; Ahlström, U; Ericson, S; Hugoson, A; Kvint, S

    1991-02-01

    The effects of impacted lower 3rd molar surgery on periodontal tissues in the adjacent 2nd molar area have been investigated in a prospective study comprising 176 cases from 2 age groups: less than or equal to 20 years (n = 93) and greater than or equal to 30 years (n = 83), respectively. The preoperative and 1-year postoperative examinations included both clinical and radiographic variables. All patients were subjected to a standardized surgical procedure and optimal plaque control pre-, intra- and postoperatively. Early removal of impacted lower 3rd molars with large angulation and close positional relationship to the adjacent 2nd molar proved to have a beneficial effect on periodontal health. PMID:2019777

  3. Treatment of space loss caused by submerged maxillary second primary molar

    Directory of Open Access Journals (Sweden)

    Karacay S

    2007-03-01

    Full Text Available Submersion is a clinical term describing a tooth depressed below the occlusal plane. In this case report, we present the treatment of a patient who had totally submerged primary maxillary second molar, which caused impaction of the second premolar and space loss in the maxillary arch due to tipping of adjacent teeth. A 12-year-old girl was referred to the pediatric dentistry clinic. The intra-oral examination revealed that right maxillary second primary molar was localized buccal side of posterior maxillary alveolar process, being almost completely covered by gingiva and adjacent teeth inclined closing the space of the related teeth completely. Periapical radiograph demonstrated that maxillary second premolar was impacted. Based on clinical and radiographic findings, maxillary primary second molar was extracted. Headgear was used for the distalization of maxillary right first molar in order to create space for the impacted second premolar. Eruption begun spontaneously 6 months later.

  4. Root Canal Morphology of Mandibular First Permanent Molars in an Indian Population

    Directory of Open Access Journals (Sweden)

    Hemant Ramesh Chourasia

    2012-01-01

    Full Text Available An in vitro study was performed to determine the number of roots, root canals per tooth, root canal configurations, and frequency of isthmi and apical deltas in mandibular first permanent molars in an Indian population. Hundred and fifty mandibular first permanent molars were collected and subjected to clearing technique. The cleared teeth were examined in a stereomicroscope under 7.5x magnifications. The canal configurations were categorized using Vertucci's classification. Overall 94.6% of the mandibular first molars had two roots, and 5.3% had extradistal roots (distolingual root. In addition, 64% of the specimens had three root canals, and 36% had four root canals. The most common canal configurations of mesial and distal roots were Vertucci type IV (54% and type I (65.3%, respectively. Clinician should be aware of the complex root canal morphology of mandibular first molars among the Indian population before and during the root canal treatment.

  5. Endodontic Management of Mandibular First Molar with Middle Distal Canal: A Case Report

    Directory of Open Access Journals (Sweden)

    Vijay Reddy Venumuddala

    2012-01-01

    Full Text Available The knowledge of variations in root canal morphology is critical for a successful endodontic treatment. This article presents the endodontic management of a unique case of mandibular molar with middle distal canal which is quite uncommon.

  6. Mandibular second molar with 3 mesial canals and a radix paramolaris

    Directory of Open Access Journals (Sweden)

    N Ragavendran

    2014-01-01

    Full Text Available Mandibular first molar commonly has two roots, the mesial and the distal root. Surprisingly in some mandibular first molar has an unusual extra third root in between mesial and distal root. This extra root is the most commonly seen in lingual side and is called as radix entomolaris. If this extra root is seen on the buccal side, it is termed as radix paramolaris (RP, which is a very rare phenomenon. Recently, various case report studies has shown the presence of third canal in the mesial and distal roots of mandibular molars. They are named as middle mesial and middle distal canal, respectively. Here, we present a case report of mandibular second molar showing three canals in the mesial root and a RP.

  7. Simplifying Chemical Reactor Design by using Molar Quantities Instead of Fractional Conversion.

    Science.gov (United States)

    Brown, Lee F.; Falconer, John L.

    1987-01-01

    Explains the advantages of using molar quantities in chemical reactor design. Advocates the use of differential versions of reactor mass balances rather than the integrated forms. Provides specific examples and cases to illustrate the principles. (ML)

  8. The Effect of Sutureless Surgery on Postoperative Pain and Swelling Following Mandibular Third Molar Surgery

    OpenAIRE

    Mozhgan Kazemian; Majid Eshghpour; Sina Ilkhani; Nafise Ghadirimoghaddam

    2016-01-01

    Introduction: surgeons have always sought to use techniques to decrease pain and swelling. One of the solutions that can minimize these complications is closing the wound with the minimum number of sutures or sutureless technique. The goal of this study was to evaluate the role of sutureless technique in decreasing pain and swelling after impacted mandibular third molar surgery. Methods: nineteen patients with bilaterally mandibular impacted third molars (one side as control and the other as ...

  9. Alternative approach to management of early loss of second primary molar: a clinical case report.

    Science.gov (United States)

    Agarwal, Ravi; Chaudhry, Kalpna; Yeluri, Ramakrishna; Singh, Chanchal; Munshi, Autar K

    2014-05-01

    Preservation of space after premature loss of the second primary molar is essential to prevent mesial drifting of the permanent first molar. Various modifications of distal shoe space maintainers, which have been documented, are all nonfunctional in nature. This paper describes an innovative design of a functional distal shoe space maintainer that is intended to overcome the disadvantages of conventional non-functional space maintainers and that does not hamper the periodontal status of the abutment tooth.

  10. Analisi alla Micro-TC dell’ Anatomia Complessa del Primo Molare Superiore

    OpenAIRE

    Formisano, Anna

    2013-01-01

    Il primo molare superiore presenta un'anatomia complessa tale da interessare numerosi studiosi nel corso dei decenni. Lo scopo di questo lavoro è stato caratterizzare l’anatomia esterna ed interna delle radici mesiovestibolare (MV), distovestibolare (DV) e palatale (P) del primo molare superiore mediante microtomografia compiuterizzata (μCT). Particolare attenzione è stata posta nel trovare la distanza orizzontale tra gli imbocchi principali MV1 della radice mesiovestibolare e quelli dei...

  11. Molar Incisor Hypomineralization: An Epidemiological Study with Prevalence and Etiological Factors in Indian Pediatric Population

    OpenAIRE

    Mishra, Apurva; Ramesh K Pandey

    2016-01-01

    ABSTRACT Aims: To determine the prevalence of molar incisor hypomineralization (MIH) in Indian children and to analyze the possible etiological factors. Materials and methods: First permanent molars and all permanent incisors were examined in 1,369 children aged 8 to 12 years. Examinations were performed by two calibrated observers. The subjects were evaluated using judgment criteria proposed by Weerheijm et al in 2003. The parents accompanying children were given a questionnaire regarding pr...

  12. Radiographic Evaluation of Third Molar Development in 5- to 25 Year Olds in Tehran, Iran

    OpenAIRE

    Jafari, A; SZ. Mohebbi; MR Khami; M. Shakur Shahabi; Naseh, M.; F. Elhami; Shamshiri AR "

    2012-01-01

    Objective: Radiographic evaluation of the third molar tooth to determine its position and degree of development is an important part in diagnosis and treatment planning, as well as in forensic dentistry procedures. The objective was to investigate the developmental stages of third molars in relation to chronologic age, gender and location (maxillary/mandibular) in an Iranian population. Materials and Methods: The data were collected in departments of pediatric dentistry and orthodontics, Tehr...

  13. Multivariate Analysis of Factors Affecting Presence and/or Agenesis of Third Molar Tooth

    OpenAIRE

    Alam, Mohammad Khursheed; Hamza, Muhammad Asyraf; Khafiz, Muhammad Aizuddin; Rahman, Shaifulizan Abdul; Shaari, Ramizu; Hassan, Akram

    2014-01-01

    To investigate the presence and/or agenesis of third molar (M3) tooth germs in orthodontics patients in Malaysian Malay and Chinese population and evaluate the relationship between presence and/or agenesis of M3 with different skeletal malocclusion patterns and sagittal maxillomandibular jaw dimensions. Pretreatment records of 300 orthodontic patients (140 males and 160 females, 219 Malaysian Malay and 81 Chinese, average age was 16.27±4.59) were used. Third-molar agenesis was calculated with...

  14. Occlusal morphology of permanent mandibular first and second molars in Gujarati population

    Directory of Open Access Journals (Sweden)

    Bhavik Dholia

    2015-01-01

    Full Text Available Background: Dental identification has been used since long time for disaster victim identification protocol. There is a difference of opinion regarding whether ethnicity influences dental morphology or not. Few studies have shown the associations between these dental features and crown traits in humans using quantitative methods. The present study is an attempt to find correlation of occlusal morphology of Gujarati population with forensic Odontology. Aim: To study different occlusal morphology of permanent mandibular first and second molars in Gujarati Population. Materials and Methods: This study comprised of a total of 100 participants of Gujarati origin, selected by random sampling method. Total number of cusps and groove patterns of mandibular first and second molar were examined clinically and photographs of the same were taken. A descriptive statistics, Chi-square test and Student t-test were used for analysis of data. Results: Mandibular first molar with 5 cusps in 71%, 4 cusps in 18% and 6 cusps in 11% were noted in the study. Mandibular first molars with "+" groove pattern in 39.5% and "Y" groove pattern in 60.5% were recorded. Mandibular second molar with 5 cusps in 6.5% and 4 cusps in 93.5% were recorded in the study. Mandibular second molars with "+" groove pattern in 93.5% and "Y" groove pattern in 6.5% were recorded. Conclusion: The most common occlusal morphology in permanent mandibular first molar is "5 cusp" and "Y" groove pattern in about 47% and for second molar is "4 cusp" and "+" groove pattern in 88.5% of Gujarati population. It may be concluded that variation in degree of expression and frequency of teeth in dentitions of different populations is different, which may help in forensic identification.

  15. PERAWATAN PULPOTOMI MORTAL SATU KALI KUNJUNGAN PADA MOLAR SULUNG NON VITAL (Laporan Kasus)

    OpenAIRE

    Bariah Bariah; Ismu Suharsono Suwelo

    2015-01-01

    Non-vital teeth are supposed to be treated with root canal treatment and root canal filling. However, the problem on root canal treatment on deciduous molars, especially with children who is noncooperative because the difficulty to get access to the root canal on children and root canals on deciduous molars are very complex. Mortal pulpotomy is the way to eliminate necrotic pulp tissue in pulp chamber and replace it with material filling. The material is a combination between formocresol and ...

  16. A ray of hope for the hopeless: Hemisection of mandibular molar with socket preservation

    OpenAIRE

    Pushpendra K Verma; Ruchi Srivastava; Harak C Baranwal; Anju Gautam

    2012-01-01

    Introduction: The management, treatment and long-term retention of mandibular molar teeth with furcation involvement have always been a challenge in periodontal therapy. Hemisection has been used successfully to retain teeth with furcation involvement. The term hemisection refers to the sectioning of a molar tooth, with the removal of an unrestorable root which may be affected by periodontal, endodontic, structural (cracked roots), or caries. Case Report : This case report describes a simple ...

  17. Evaluation of the anatomical alterations of lower molars mesial root?s apical third

    Directory of Open Access Journals (Sweden)

    FRÖNER Izabel Cristina

    1999-01-01

    Full Text Available The anatomical apex of the mesial root of the lower molars presents a morphological complexity related to the number and shape of the root canals as well as of the apical foramen and isthmus presence. The knowledge of the complexity of the endodontic system of the molar root area is essencial to select more carefully the best instrumentation and obturation technique, to obtain a more successful endodontic therapy.

  18. Osteomyelitis of the condyle secondary to pericoronitis of a third molar: a case and literature review.

    Science.gov (United States)

    Wang, R; Cai, Y; Zhao, Y F; Zhao, J H

    2014-09-01

    In this study, we report a very unusual case of a patient with osteomyelitis of the condyle secondary to pericoronitis of an impacted third molar. The patient was treated by removal of the impacted third molar, opening of the drainage, combined with systemic application of antibiotics for two weeks. This treatment option did not lead to any functional defects or facial asymmetry. The patient fully recovered and the disease did not recur.

  19. Deeply Impacted Primary Second Molar with Agenesis of the Succeeding Premolar: A Rare Case

    OpenAIRE

    Komerık, Nurgul; Kırzıoglu, Zuhal; Erdogan, Yildirim

    2013-01-01

    Tooth impaction is seen relatively commonly in the permanent dentition with the most frequently involved teeth being the third molars and canines. Impaction of primary teeth, particularly primary type of impaction, is considered a rare event. This report focuses on impaction of mandibular right second primary molar and absence of mandibular permanent second premolar with dens invaginatus in maxillary incisors in a 11 year old girl. Case report (J Int Dent Med Res 2013; 6: (1), pp. 45-48)

  20. Agenesis of premolar associated with submerged primary molar and a supernumerary premolar: An unusual case report

    Directory of Open Access Journals (Sweden)

    S. V. S. G. Nirmala

    2012-01-01

    Full Text Available The combination of submerged primary molar, agenesis of permanent successor with a supernumerary in the same place is very rare. The purpose of this article is to report a case of submerged mandibular left second primary molar with supernumerary tooth in the same region along with agenesis of second premolar in an 11-year-old girl, its possible etiological factors, and a brief discussion on treatment options.

  1. A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

    Science.gov (United States)

    Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

    2015-05-01

    Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. PMID:25840859

  2. Efficiency of gaseous ozone in reducing the development of dry socket following surgical third molar extraction

    OpenAIRE

    Ahmedi, Jehona; Ahmedi, Enis; Sejfija, Osman; Agani, Zana; Hamiti, Vjosa

    2016-01-01

    Objective: The objective of this study was to assess the efficacy of ozone gas (O3) on the reduction of dry socket (DS) occurrence following surgical extraction of lower jaw third molars, influence of the indication for the extraction, and the difficulty of extraction on the incidence of DS. Materials and Methods: This study included thirty patients with bilaterally impacted third molars of mandible requiring surgical procedure for extraction. Following extraction, in the control group, salin...

  3. The Influence of Post in Endodontically Treated Molar Abutment on Fixed Dentures Success Rate

    OpenAIRE

    Pralita Kusumawardhini; Alysia Henrietta; Saraventi Saraventi

    2013-01-01

    Many dentists believe that the tooth need reinforcement provided by post before the definite restoration is placed. However, others suggest not to use post when posterior teeth especially molars, still have significant amount of tooth structure. Therefore, when endodontically treated molar is considered to be used as fixed denture abut-ment, clinicians must have proper knowledge about the impact of post placement. This literature will describe considerations regarding post placement in endodo...

  4. Long-Term Clinical Performance of Aesthetic Restorations in Primary Molars: A Case Report

    OpenAIRE

    Pomarico, Luciana; Neves, Beatriz Gonçalves; Maia, Lucianne Cople; Primo, Laura Guimarães

    2011-01-01

    There is a great diversity of restorative materials and techniques for deciduous molars with significant coronal destruction, including resin composite restorations and biologic restorations (portions of natural teeth). By using 4 evaluation methods, this study aimed at longitudinally evaluating the effectiveness of restorations in the deciduous molars of a patient having high caries activity, using adhesive techniques. The evaluation methods consisted of the fibre-optic transillumination met...

  5. Fracture Resistance of Pulpotomized Primary Molar Restored with Extensive Class II Amalgam Restorations

    Directory of Open Access Journals (Sweden)

    F. Mazhari

    2008-06-01

    Full Text Available Objective: The aim of the present study was to evaluate fracture resistance of pulpoto-mized primary molar teeth restored with extensive multisurface amalgam restorations.Materials and Methods: Eighty extracted carious human primary molar teeth were se-lected forpresent study. Teeth were divided in to eight groups of ten. Mesio- or disto-occlusal and Mesio-occluso-distal cavities with different cavity wall thickness (1.5 or 2.5mm were prepared in both first and second primary molar teeth. After restoring teeth with amalgam, all specimens were stored in distilled water at 37°C for 7 days. Then samples were thermocycled for 1000 cycles from 5°C to 55°C. The specimens then were subjected to a compressive load in a universal testing machine at a crosshead speed of 0.5 mm min-1. ANOVA and t-test were used for statistical analysis.Results: Mean fracture resistance of first and second molar teeth were 975.5 N (SD=368.8 and 1049.2 N (SD=540.1 respectively. In the first molar group, fracture resis-tance of two-surface cavities was significantly more than three-surface cavities (P<0.001, however this difference was not statistically significant in the second molar group. In both first and second molar group, fracture resistance incavities with 2.5 mm wall thickness, was significantly more than the group with 1.5 mm wall thickness.Conclusion: The mean fracture resistance in pulpotomized primary molar restored with amalgam restorations was higher than reported maximum bite force in primary teeth even in extensive multi-surface restorations. Therefore, the teeth with large proximal carious lesions in schoolchildren could be restored with amalgam.

  6. Occlusal morphology of permanent mandibular first and second molars in Gujarati population

    Science.gov (United States)

    Dholia, Bhavik; Manjunatha, Bhari Sharanesha

    2015-01-01

    Background: Dental identification has been used since long time for disaster victim identification protocol. There is a difference of opinion regarding whether ethnicity influences dental morphology or not. Few studies have shown the associations between these dental features and crown traits in humans using quantitative methods. The present study is an attempt to find correlation of occlusal morphology of Gujarati population with forensic Odontology. Aim: To study different occlusal morphology of permanent mandibular first and second molars in Gujarati Population. Materials and Methods: This study comprised of a total of 100 participants of Gujarati origin, selected by random sampling method. Total number of cusps and groove patterns of mandibular first and second molar were examined clinically and photographs of the same were taken. A descriptive statistics, Chi-square test and Student t-test were used for analysis of data. Results: Mandibular first molar with 5 cusps in 71%, 4 cusps in 18% and 6 cusps in 11% were noted in the study. Mandibular first molars with “+” groove pattern in 39.5% and “Y” groove pattern in 60.5% were recorded. Mandibular second molar with 5 cusps in 6.5% and 4 cusps in 93.5% were recorded in the study. Mandibular second molars with “+” groove pattern in 93.5% and “Y” groove pattern in 6.5% were recorded. Conclusion: The most common occlusal morphology in permanent mandibular first molar is “5 cusp” and “Y” groove pattern in about 47% and for second molar is “4 cusp” and “+” groove pattern in 88.5% of Gujarati population. It may be concluded that variation in degree of expression and frequency of teeth in dentitions of different populations is different, which may help in forensic identification. PMID:26005303

  7. Comparison of sexual dimorphism of permanent mandibular canine with mandibular first molar by odontometrics

    Science.gov (United States)

    Agrawal, Aditi; Manjunatha, Bhari Shranesha; Dholia, Bhavik; Althomali, Yousef

    2015-01-01

    Background and Objectives: Sexual dimorphism is one of important tool of forensic science. The objective of this study is to assess the dimorphic status of mesio-distal (MD) and bucco-lingual (BL) diameter of mandibular canine with mandibular first molar among the students of dental college. This study is of definite significance as sex chromosomes and hormonal production influenced tooth morphology. Materials and Methods: The descriptive study adopted the purposive sampling technique, of 50 male and 50 female aged 17-25 years, using study casts for mesio-distal and bucco-lingual dimensions of mandibular canine with mandibular first molar were taken using digital Vernier caliper. The data obtained were subjected to statistical analysis using descriptive statistics and t-test to compare MD and BL dimensions in male and female populations and P ≤ 0.05 was found statistically significant. Results: Sexual dimorphism can be predicted by measuring mesiodistal dimension of mandibular canine and mandibular first molar. The left mandibular canine showed more sexual dimorphism (12.66%) in comparison to left mandibular first molar (0.824%) only. Right mandibular canine showed greater dimorphism in MD dimensions (10.94%) in comparison to right mandibular first molar (6.96%). In bucco-lingual dimensions mandibular canine showed less variability when compared with mandibular first molar, thus our study showed more significance on mesio-distal dimensions of both teeth. Conclusion: The present study concludes statistically significant sexual dimorphism in mandibular canine over mandibular first molar on study casts. The MD dimensions in mandibular canine and mandibular first molar can help in determining sex and identification of unknown person. PMID:26816466

  8. Morphometric evaluation and planning of anticurvature filing in roots of maxillary and mandibular molars

    OpenAIRE

    Maria Antonieta Veloso Carvalho OLIVEIRA; Jessyca Figueira VENÂNCIO; Luís Henrique Araújo RAPOSO; Nelson BARBOSA JÚNIOR; João Carlos Gabrielli BIFFI

    2015-01-01

    This study aimed to guide the planning of anticurvature filing using pre-determined anatomical points on teeth to establish directions for proper implementation of the technique. Two hundred digital periapical radiographs of human molar teeth were selected and divided into two groups (n = 100): MX (maxillary) and MD (mandibular) molars. Mesiobuccal roots were considered for the MX group and mesial roots for the MD group. Pre-determined anatomical points required for planning the anticurvature...

  9. An In Vitro Study of Mesiobuccal Root Thickness of Maxillary First Molars

    OpenAIRE

    Mohammadzadeh Akhlaghi, Nahid; Ravandoust, Yasaman; Najafi, Mohammad; Dadresanfar, Bahareh

    2012-01-01

    Introduction Understanding the internal anatomy of root canal system can significantly influence outcomes of root canal treatment. The aim of this in vitro study was to measure the thickness of mesiobuccal root at different levels in maxillary first molars. Materials and Methods In this cross-sectional study, forty extracted human maxillary first molars were radiographed; accordingly, the mesial and distal root thicknesses of mesiobuccal (MB) roots were measured at four parallel horizontal le...

  10. Evaluation of the flaring in mandibular molars danger zone using ProTaper rotatory system

    OpenAIRE

    Fernanda Missao Brugin MATSUBARA; Janaina Glaucia Trevizan PEREIRA; Flares BARATTO FILHO; Gisele Aihara HARAGUSHIKU; Flávia Sens FAGUNDES

    2005-01-01

    The aim of this study was to evaluate in vitro the flaring in mandibular molars danger zone, after root canal instrumentation with the ProTaper rotatory instrument system. Sixty extracted mandibular molars with fully formed apices had the mesial roots sectioned. The specimens were divided into four groups and instrumented until Shaping X, Shaping 1 and Shaping 2 files, respectively. One group was kept as control with no instrumentation. The results submitted to statistical analysis, showed ...

  11. Anatomical Relationship of Lingual Nerve to the Region of Mandibular Third Molar

    OpenAIRE

    Marcelo Breno Meneses Mendes; Carla Maria de Carvalho Leite Leal Nunes; Maria Cândida de Almeida Lopes

    2014-01-01

    ABSTRACT Objectives This study evaluated the relationship of the lingual nerve with the adjacent anatomical structures of the mandibular third molar region, influencing the dentist to be aware of the variability of these relationships. Material and Methods Samples of 24 human corpse half-heads were selected and divided according with the presence or absence of the mandibular third molars. The lingual nerve (LN) was explored, showing its run from the oblique line until its crossing with the su...

  12. Revolution vs status quo? Non-intervention strategy of asymptomatic third molars causes harm.

    Science.gov (United States)

    Toedtling, V; Yates, J M

    2015-07-10

    The Faculty of Dental Surgery of the Royal College of Surgeons of England has prompted the National Institute for Health and Care Excellence to urgently re-assess the TA1 guidance on extractions of wisdom teeth and highlighted required amendments to the present version in light of published evidence concerning the harm caused by wisdom tooth retention. This article seeks to address the recent concerns relating the increasing frequency of distal-cervical caries in lower second molar teeth when associated with asymptomatic partially erupted mesial or horizontal impacted mandibular third molars. Such acute angle impactions are classified as partially erupted when one of the third molar cusps breached the epithelial attachment of the distal aspect of the second molar, thus prevents the formation of a gingival seal. At its earliest stage the wisdom tooth appears clinically absent or unerupted, yet histologically the architecture of the gingival epithelium has been disrupted allowing ingress of microbes, demineralisation and succeeding cavitation to take place on the distal aspect of the second molar. We hope to highlight the difficulties faced in addressing this growing clinical problem and encourage clinicians to re-evaluate their own caries risk assessment and caries prevention strategy in relation to mesial and horizontal third molar extractions. PMID:26159975

  13. Efficacy of the technique of piezoelectric corticotomy for orthodontic traction of impacted mandibular third molars.

    Science.gov (United States)

    Ma, Zhigui; Xu, Guangzhou; Yang, Chi; Xie, Qianyang; Shen, Yuqing; Zhang, Shanyong

    2015-04-01

    Our aim was to assess the efficacy of piezoelectric corticotomy for orthodontic traction of mandibular third molars close to the inferior alveolar nerve. Thirty patients with impacted third molars close to the nerve were included in the study, 15 of whom were treated with conventional orthodontic traction and 15 with piezoelectric corticotomy. We recorded duration of treatment including exposure and orthodontic traction, and time to the final extraction. Postoperative complications including trismus, swelling, and pain were also noted. Alveolar bone levels mesial and distal to the second molars were evaluated on cone-beam computed tomographic (CT) images. Student's t test was used to assess the significance of differences between the groups. After orthodontic treatments all impacted third molars were successfully removed from the inferior alveolar nerve without neurological damage. The mean (SD) duration of surgical exposure in the piezoelectric corticotomy group was significantly longer than that in the conventional group (p=0.01). The mean (SD) duration of traction was 4 (2.3) months after piezoelectric corticotomy, much shorter than the 7.5 (1.3) months in the conventional group (p=0.03). There were no significant differences in postoperative complications between the groups. There was a significant increase in the distal alveolar height of second molars after treatment in both groups (pcorticotomy allows more efficient and faster traction of third molars with a close relation between the root and the inferior alveolar nerve, although it took longer than the traditional technique. PMID:25638568

  14. Dental age estimation from the developmental stage of the third molars in western Chinese population.

    Science.gov (United States)

    Li, Guo; Ren, Jiayin; Zhao, Shuping; Liu, Yuanyuan; Li, Na; Wu, Wanhong; Yuan, Shanshan; Wang, Hu

    2012-06-10

    The purpose of this study is to provide reference data about estimating dental age from third molars of the western Chinese population for comparing with other populations and being applied to the age estimation of western Chinese juveniles and adolescents. A total of 2078 digital panoramic radiographs of 989 male and 1089 female Chinese subjects aged between 5 and 23 years were examined. The mineralization status of the third molars was assessed using the formation stages described by Demirjian et al. with two modifications. The results showed that the development of third molars in the western Chinese population was likely to begin at age 5 in both males and females. The third molars 28 and 48 showed significantly higher frequency in females than in males. The third molars 18 in the stage 1, 38 in the stages 1, A and G, and 48 in the stage H showed significantly older average age in females than in males. The Demirjian's stages C and D could be used as a reference stage to determine dichotomously whether a western Chinese is more likely to be under or above age 14 or 16, respectively. This study provided reference data for the age estimation of western Chinese juveniles and adolescents by the mineralization stages of the third molar. Apart from forensic age determination in living subjects, the presented reference data can also be used for age estimations of unidentified corpses and skeletons.

  15. Third-molar development in relation to chronologic age in young adults of central China.

    Science.gov (United States)

    Bai, Yuming; Mao, Jing; Zhu, Shengrong; Wei, Wei

    2008-08-01

    The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages (A-H) method of Demirjian and the third-molar development was compared, in terms of sex and age, with results of previous studies. The samples consisted of 291 orthopantomograms from young Chinese subjects of known chronologic age and sex (including 139 males with a mean age of 14.67+/-3.62 y and 152 females with a mean age of 14.85+/-3.70 y). Statistical analysis was performed by employing the Mann-Whitney U-test and the t-test. Regression analysis was conducted to obtain regression formulas for calculating dental age from the chronologic age. Our results showed statistically significant differences (Pthird-molar development between males and females, at the calcification stages D, E and H. And a strong correlation was found between age and third-molar development in both males (r (2)=0.65) and females (r (2)=0.61). New equations (Age=8.76+1.32 Development stage) for estimating chronologic age were derived. It is concluded that third-molar genesis took place earlier in males than in females. The use of third molars as a developmental marker is appropriate in young adults of Central China. The formula obtained in the present study can be used as a guide for estimation of dental maturity and a standard for age estimation for young adults of Central China.

  16. Success Rate of Zinc Oxide Eugenol in Pulpectomy of Necrotic Primary Molars: A Retrospective Study

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2015-06-01

    Full Text Available Introduction: Pulpectomy is a conservative treatment plan for primary necrotic teeth and Zinc Oxide Eugenol is still a good choice as root canal filling material but long term studies on poor prognosis molars are limited and almost contradictory. The purpose of this study is to evaluate the clinical and radiographical success rate of pulpectomy of necrotic primary molars using ZOE as the root canal filling material. Methods: 152 records of 76 primary molars on which two-visit pulpectomy had been performed were selected. The records with a complete and enough clinical history and high quality radiographs of before the treatment and follow up sessions were included to the study. The least follow up was 6 months and the most one was 59 months (with the mean follow up of 24 months. The treatments were noted successful if clinically had no signs and symptoms and radiographically, the size of pathologic radiolucencies of before the treatment have been reduced or at least remained without any changes. Then obtained information was analyses in SPSS 17 and by Chi- square and Log Rank tests. Results: From all 76 cases 5 teeth (6.6% were radiographically failed that all of them were second primary molars and 2 teeth were clinically failed (2.6% that both were second primary molars. Conclusion: Two-visit pulpectomy of primary molars with ZOE as root canal filling materials is one of the most successful treatments for necrotic teeth

  17. Occlusal migration of the maxillary first primary molars subsequent to the loss of antagonists.

    Science.gov (United States)

    Yonezu, T; Machida, Y

    1997-08-01

    The purpose of this study was to observe the vertical changes in unopposed maxillary first primary molars longitudinally. The subjects of this study were 17 children whose lower first primary molars had to be extracted. Space closure were prevented by crown-loop space maintainers for all these children. Plaster casts were made every 4 months for 16 to 24 months after the extraction. These series of casts were standardized, and vertical changes of the maxillary first primary molars against the occlusal plane were measured using a micro-reader. The mean changes indicated that maxillary first primary molars without intercuspidation tend to drift toward the extraction space. On the control side with antagonists, the maxillary first molars seemed to move reversed to apical throughout the observation period. Accordingly, the results of this study showed new trends after the premature loss of primary molars. The vertical changes toward extraction space varied from -0.40 mm to 1.43 mm at the 16 months after extraction. Mean changes were small, but there were some individual differences in reaction, giving negative values. However, we should always be concerned about loss of arch length and also occlusal drift of unopposed teeth, because the vertical changes were greater than 1 mm at 16 months after extraction in some cases.

  18. Dental caries characteristics in the first permanent molar in school age children.

    Directory of Open Access Journals (Sweden)

    Yoel González Beriau

    2009-04-01

    Full Text Available Background: Dental caries is one of the main health problems in children. The first permanent molar presents caries more frequently than any other. Objective: To describe the characteristics of dental caries in the first permanent molars in children between 6 and 13 years-old, and to assess oral hygiene and knowledge about the subject in all the patients treated in the stomatology consultation Barrio adentro “El Guapo”, from November 2005 to March 2006. Methods: A descriptive, transversal study showed that most of the patients had dental caries. It was proved that many of them had, at least, on of the first molars affected by dental caries. The quotient first molar affected/ patient was higher than one. Results: There was a decrease in the percentage of healthy permanent first molars. Poor oral hygiene prevailed, with a medium knowledge level on the subject. Most of the parents didn´t know about the first molar dental cavity. Conclusions: It was needed to perform educative tasks aimed at this age group to avoid further damage to this important tooth, central for the development of the stomatognathic system.

  19. Sharp mandibular bone irregularities after lower third molar extraction: Incidence, clinical features and risk factors

    Science.gov (United States)

    Alves-Pereira, Daniela; Valmaseda-Castellón, Eduard; Laskin, Daniel M.; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

    2013-01-01

    Objectives: The purpose of this study was to determine the incidence and clinical symptoms associated with sharp mandibular bone irregularities (SMBI) after lower third molar extraction and to identify possible risk factors for this complication. Study Design: A mixed study design was used. A retrospective cohort study of 1432 lower third molar extractions was done to determine the incidence of SMBI and a retrospective case-control study was done to determine potential demographic and etiologic factors by comparing those patients with postoperative SMBI with controls. Results: Twelve SMBI were found (0.84%). Age was the most important risk factor for this complication. The operated side and the presence of an associated radiolucent image were also significantly related to the development of mandibular bone irregularities. The depth of impaction of the tooth might also be an important factor since erupted or nearly erupted third molars were more frequent in the SMBI group. Conclusions: SMBI are a rare postoperative complication after lower third molar removal. Older patients having left side lower third molars removed are more likely to develop this problem. The treatment should be the removal of the irregularity when the patient is symptomatic. Key words:Third molar, postoperative complication, bone irregularities, age. PMID:23524429

  20. A novel chitin binding crayfish molar tooth protein with elasticity properties.

    Directory of Open Access Journals (Sweden)

    Jenny Tynyakov

    Full Text Available The molar tooth of the crayfish Cherax quadricarinatus is part of the mandible, and is covered by a layer of apatite (calcium phosphate. This tooth sheds and is regenerated during each molting cycle together with the rest of the exoskeleton. We discovered that molar calcification occurs at the pre-molt stage, unlike calcification of the rest of the new exoskeleton. We further identified a novel molar protein from C. quadricarinatus and cloned its transcript from the molar-forming epithelium. We termed this protein Cq-M13. The temporal level of transcription of Cq-M13 in an NGS library of molar-forming epithelium at different molt stages coincides with the assembly and mineralization pattern of the molar tooth. The predicted protein was found to be related to the pro-resilin family of cuticular proteins. Functionally, in vivo silencing of the transcript caused molt cycle delay and a recombinant version of the protein was found to bind chitin and exhibited elastic properties.

  1. MOLAR. Measuring and modelling the dynamic response of remote mountain lake ecosystems to environmental change: A programme of Mountain Lake Research. MOLAR Project Manual. Draft of September 1996

    Energy Technology Data Exchange (ETDEWEB)

    Wathne, B.M.

    1996-09-01

    This report lays down the practical working methods of the MOLAR project. Requirements on preparatory work and methods for sampling in the field are given in detail. Also sample handling after field work, where to send the sample material for further analysis and how to treat the results are described. 97 refs., 10 figs., 14 tabs.

  2. Danger zone in mandibular molars before instrumentation: an in vitro study Zona de risco em molares inferiores previamente a instrumentação: estudo "in vitro"

    Directory of Open Access Journals (Sweden)

    Paulo Ferreira Garcia Filho

    2003-12-01

    Full Text Available The aim of this work was to measure the danger zone in mandibular molars, relating to strip perforations that might affect the mesial root during canal instrumentation. One hundred mesial roots were sectioned 2mm below the furcation and the distal concavities were measured with a microscope from the border of the canals to the outer dentin of the root. The average thickness of the danger zone of the mesial roots was 0.789 +/- 0.182mm. No significant statistical differences were observed comparing the danger zone of mesiobuccal and mesiolingual canals.O objetivo deste estudo foi medir as zonas de risco de raízes mesiais de molares inferiores, demonstrando porque perfurações radiculares podem ocorrer durante o preparo do sistema de canais radiculares. Cem raízes mesiais de molares inferiores foram seccionadas horizontalmente 2mm abaixo da bifurcação e as concavidades distais foram medidas com o auxílio de um microscópio, desde a borda dos canais até a superfície externa da raiz. A espessura média para as zonas de risco das raízes mesiais foi 0,789 +/- 0,182 mm. Não houve diferença estatística significante entre as medidas das zonas de risco nos canais mésio-vestibulares e mésio-linguais de molares inferiores.

  3. Energy Dissipation and Apparent Viscosity of Semi-solid Metal during Rheological Processes Part Ⅱ: Apparent Viscosity

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study investigated the rheological properties of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry preparing,delivering and model filling. The rheological properties of SSM (semi-solid metal) slurry was described by an analytical model in terms of microstructural parameters, which consist of effective solid fraction, particle size and shape, and flow parameters such as mean velocity, fluctuant velocity and relative velocity between liquid and solid phase. The model was verified in the experiment of A356 alloys with a coaxial double-bucket rheometer. And the maximum relative error between the theoretical value and measured one is less than 10%.The results of experiment and theoretical calculation also indicate that the microstructural parameters and flow parameters are two major factors that affect the apparent viscosity of semi-solid alloys, and fluctuant velocity and relative velocity between liquid and solid phase are the key factors to distinguish between steady and transient rheological properties.

  4. Radiographic evaluation of third molar genesis in Greek orthodontic patients

    Directory of Open Access Journals (Sweden)

    Barka G

    2013-09-01

    Full Text Available Georgia Barka,1 Konstantinos Marathiotis,2 Michael Protogerakis,3 Andreas Zafeiriadis4 1Department of Dentoalveolar Surgery, Implant Surgery and Radiology, School of Dentistry, Aristotle University of Thessaloniki, 2School of Biology, Faculty of Science and School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece; 3Clinical Implant Dentistry, School of Dental Sciences, Newcastle University, Newcastle Upon Tyne, UK; 4Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece Objectives: The study reported here investigated the first radiographic evidence of third molar (M3 formation, their incidence and distribution as well as their congenital absence on the right or the left side in either the maxilla or the mandible, in both male and female Greek orthodontic patients. Materials and methods: A total of 618 panoramic radiographs were initially examined. After the application of inclusion/exclusion criteria, the group finally selected consisted of 428 patients (mean age 11.64 years, range 5–18: 179 males (mean age 11.73 ± 2.46 and 249 females (mean age 11.57 ± 2.45. The collected data were analyzed using SPSS software (IBM, Armonk, New York, NY, USA. The level of significance for all analyses was set to p = 0.05. The chi-square (χ2 test was used to assess the relationships between variables. The Wilcoxon’s signed-rank test and the Mann–Whitney U test were also used for comparisons as well as the Spearman’s rho test for correlations. Results: M3s were first detected in females at the age of 7 years whereas males followed one year later at the age of 8 years. A strong correlation between age and M3 development was revealed for both sexes (Spearman’s rho = 0.177, p = 0.05. Presence of all four M3s was the most common incidence (present in 70.8% of study subjects, followed by the agenesis of two (12.1%, agenesis of all four (8.4%, one (6.8%, and three (1.9% M3s

  5. Pictet's experiment: The apparent radiation and reflection of cold

    Science.gov (United States)

    Evans, James; Popp, Brian

    1985-08-01

    Towards the end of the eighteenth century it was discovered by Marc-Auguste Pictet of Geneva that cold emanations from a flask of snow could be reflected and focused by mirrors in the same way as the emanations from a heated object. Pictet's discovery had an invigorating effect on research on radiant heat. We sketch the scientific milieu in which Pictet worked, describe the line of investigation that led him to his discovery, and summarize the theoretical explanations offered by Pictet and his contemporaries for this and related experiments. A simple qualitative explanation in modern terms is offered for the apparent radiation and reflection of cold. Finally, detailed directions are provided for replicating the experiment as a demonstration for the lecture hall.

  6. Considerations about the apparent superluminal expansions in astrophysics

    International Nuclear Information System (INIS)

    The ortodox models devised to explain the apparent ''superluminal expansions'' observed in astrophysics, and here briefly summarized and discussed together with th experimental data, do not seem to be to much successful. Especially when confronted with the most recent observations, suggesting complicated expansion patterns, even with possible accelerations. At this point it may be, therefore, of some interest to explore the possible alternative models in which actual superluminal motion take place. To prepare the ground one starts from a variational principle, introduces the elements of a tachyon mechanics within special relativity, and argues about the expected behaviour of tachyonic objects when interacting (gravitationally, for instance) among themselves or with ordinary matter. Then the simplest ''superluminal models'', paying particular attention to the observations which they would give rise to are revie wed and developed. It is concluded that some of them appear to be physically acceptable and are statistically favoured with respect to the ortodox ones

  7. When luminance increment thresholds depend on apparent lightness.

    Science.gov (United States)

    Maertens, Marianne; Wichmann, Felix A

    2013-05-31

    A fundamental question in visual perception research is whether the sensitivity to stimulus differences is limited by the sensory representation of the external stimulus, that is, the proximal stimulus, or by its perceptual representation, i.e., stimulus appearance. In the domain of lightness perception, the question translates into whether discrimination thresholds depend on the local luminance in the retinal image or on the apparent lightness of the corresponding image region. The majority of findings seem to indicate that sensitivity is limited by the sensory stimulus representation, which would imply different mechanisms for stimulus discrimination and appearance. We think this conclusion needs to be qualified. We report data suggesting that the relationship between discrimination and appearance judgments depends on how exactly they are being measured. We propose a theoretical account that provides a common mechanism for appearance and sensitivity. An interesting corollary of this model is that it also accounts for the perceptual phenomenon of assimilation.

  8. Apparent diffusion coefficient measurements in progressive supranuclear palsy

    International Nuclear Information System (INIS)

    We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes. (orig.)

  9. Apparent diffusion coefficient measurements in progressive supranuclear palsy

    Energy Technology Data Exchange (ETDEWEB)

    Ohshita, T.; Oka, M.; Imon, Y.; Yamaguchi, S.; Mimori, Y.; Nakamura, S. [Hiroshima Univ. (Japan). School of Medicine

    2000-09-01

    We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes. (orig.)

  10. Plant-mediated 'apparent effects' between mycorrhiza and insect herbivores.

    Science.gov (United States)

    Gilbert, Lucy; Johnson, David

    2015-08-01

    Plants mediate indirect 'apparent' effects between above-ground herbivores and below-ground mutualistic mycorrhizal fungi. The herbivore-plant-mycorrhiza continuum is further complicated because signals produced by plants in response to herbivores can be transmitted to other plants via shared fungal networks below ground. Insect herbivores, such as aphids, probably affect the functioning of mycorrhizal fungi by changing the supply of recent photosynthate from plants to mycorrhizas, whereas there is evidence that mycorrhizas affect aphid fitness by changing plant signalling pathways, rather than only through improved nutrition. New knowledge of the transfer of signals through fungal networks between plant species means we now need a better understanding of how this process occurs in relation to the feeding preferences of herbivores to shape plant community composition and herbivore behaviour in nature.

  11. Vitrectomy for bilateral macular schisis without apparent optic disc anomalies

    Science.gov (United States)

    Andonegui, José; Maya, José Ramón; Echeverría, Marta; Alcaine, Araceli

    2016-01-01

    A 78-year-old man complained of bilateral visual acuity loss. Optical coherence tomography examination showed bilateral macular schisis with fluid accumulation in the external retinal layers without vitreous traction. Fundus examination and fluorescein angiography were normal in both eyes. Both eyes were treated by phacoemulsification, intraocular lens implantation, and vitrectomy without laser, gas exchange, or retinal fenestration. Slow and progressive fluid resorption and improvement in VA were observed in both eyes. Macular schisis similar to the one associated with optic disc anomalies is a possibility in patients without apparent disc anomalies. Vitrectomy without laser, gas, or retinal fenestration may be a good therapeutic option even in patients with a PVD preoperatively. PMID:27703873

  12. Galvanic apparent internal impedance: an intrinsic tissue property.

    Science.gov (United States)

    Golberg, Alex; Rabinowitch, Haim D; Rubinsky, Boris

    2009-11-01

    Using basic galvanic cell principles, the ability of tissues to generate electrical current through electrolysis was characterized. Studying Zn/Cu electrolysis in animal organs revealed a fundamental and measurable tissue-specific property - the galvanic apparent internal impedance (GAII), that is most likely related to the salt bridge function of tissues delineated by electrodes. Further to the fundamental knowledge acquired, GAII enables a new diagnostic method to distinguish between tissue types and to determine their health status without a need for expensive calibration, as often required when external power source is used. We demonstrated the GAII sensitivity in detecting tissue ablation with microwave heating or irreversible electroporation. The results open the way for a novel, inexpensive self-powered tissue diagnostic system for a wide range of applications such as minimally invasive tissue health status, ischemia, hydration, real time intra-operative control of minimally invasive surgery, medical imaging, virtual biopsy and many others.

  13. On the apparent CO2 absorption by alkaline soils

    Directory of Open Access Journals (Sweden)

    X. Chen

    2014-02-01

    Full Text Available Alkaline soils in the Gubantonggut Desert were recently demonstrated socking away large quantities of CO2 in an abiotic form. This demands a better understanding of abiotic CO2 exchange in alkaline sites. Reaction of CO2 with the moisture or dew in the soil was conjectured as a potential mechanism. The main goal of this study is to determine the extent to which the dew deposition modulates Land–Atmosphere CO2 exchange at highly alkaline sites (pH ~ 10. Experiments were conducted at the most barren sites (canopy coverage 2 fluxes were measured using a micro-lysimeters and an automated flux system (LI-COR, Lincoln, Nebraska, USA, respectively. There is an evident increase of dew deposition in nocturnal colder temperatures and decrease in diurnal warmer temperatures. Variations of soil CO2 flux are almost contrary, but the increase in diurnal warmer temperatures is obscure. It was shown that the accumulation and evaporation of dew in the soil motivates the apparent absorption and release of CO2. It was demonstrated that dew amounts in the soil has an exponential relation with the part in Fc beyond explanations of the worldwide utilized Q10 model. Therefore dew deposition in highly alkaline soils exerted a potential CO2 sink and can partly explain the apparent CO2 absorption. This implied a crucial component in the net ecosystem carbon balance (NECB at alkaline sites which occupies approximately 5% of the Earth's land surface (7 million km. Further explorations for its mechanisms and representativeness over other arid climate systems have comprehensive perspectives in the quaternary research.

  14. Standard Molar Enthalpy of Formation of RE(C5H8NS2)3(o-phen)

    Institute of Scientific and Technical Information of China (English)

    MENG Xiang-Xin; GAO Sheng-Li; CHEN San-Ping; YANG Xu-Wu; XIE Gang; SHI Qi-Zhen

    2005-01-01

    Five solid ternary complexes of RE(C5H8NS2)3(o-phen) (RE=Ho, Er, Tm, Yb, Lu) have been synthesized in absolute ethanol by rare earth chloride low hydrate reacting with the mixed ligands of ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline·H2O (o-phen·H2O) in the ordinary laboratory atmosphere without any cautions against moisture or air. IR spectra of the complexes showed that the RE3+ coordinated with six sulfur atoms of three PDC- and two nitrogen atoms of o-phen·H2O. It was assumed that the coordination number of RE3+was eight. The constant-volume combustion energies of the complexes, △cU, were determined as (-16788.46±7.74), (- 15434.53± 8.28), (- 15287.807.31), (- 15200.50±7.22) and (- 15254.34±6.61) kJ·mol-1, respectively, by a precise rotating-bomb calorimeter at 298.15 K. Its standard molar enthalpies of combustion, △cH m,and standard molar enthalpies of formation, △fH m, were calculated as (-16803.95 ±7.74), (-15450.02±8.28),(-15303.29±9.28), (-15215.99±7.22), (-15269.83±6.61) kJ·mol-1 and (-1115.42±8.94), (-2477.80±9.15), (-2619.95 ±10.44), (-2670.17 ± 8.22), ( -2650.06± 8.49) kJ·mol-1, respectively.

  15. Site Environmental Report for 2009, Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Suying

    2010-08-19

    Volume II of the Site Environmental Report for 2009 is provided by Ernest Orlando Lawrence Berkeley National Laboratory as a supplemental appendix to Volume I, which contains the body of the report. Volume II contains the environmental monitoring and sampling data used to generate summary results of routine and nonroutine sampling at the Laboratory, except for groundwater sampling data, which may be found in the reports referred to in Chapter 4 of Volume I. The results from sample collections are more comprehensive in Volume II than in Volume I: for completeness, all results from sample collections that began or ended in calendar year (CY) 2009 are included in this volume. However, the samples representing CY 2008 data have not been used in the summary results that are reported in Volume I. (For example, although ambient air samples collected on January 6, 2009, are presented in Volume II, they represent December 2008 data and are not included in Table 4-2 in Volume I.) When appropriate, sampling results are reported in both conventional and International System (SI) units. For some results, the rounding procedure used in data reporting may result in apparent differences between the numbers reported in SI and conventional units. (For example, stack air tritium results reported as < 1.5 Bq/m3 are shown variously as < 39 and < 41 pCi/m3. Both of these results are rounded correctly to two significant digits.)

  16. Renormalized Volume

    CERN Document Server

    Gover, A Rod

    2016-01-01

    For any conformally compact manifold with hypersurface boundary we define a canonical renormalized volume functional and compute an explicit, holographic formula for the corresponding anomaly. For the special case of asymptotically Einstein manifolds, our method recovers the known results. The anomaly does not depend on any particular choice of regulator, but the coefficients of divergences do. We give explicit formulae for these divergences valid for any choice of regulating hypersurface; these should be relevant to recent studies of quantum corrections to entanglement entropies. The anomaly is expressed as a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. We show that the variation of these energy functionals is exactly the obstruction to solving a singular Yamabe type problem with boundary data along the...

  17. The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Jacob G. [Washington River Protection Solutions, Richland, WA (United States)

    2013-01-11

    Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH{sub 4}H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results detennined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

  18. Movimentação de molares inferiores ancorados em mini-parafusos Mandibular molar uprighting, using mini-screw as anchorage

    Directory of Open Access Journals (Sweden)

    Rosana Canteras Di Matteo

    2005-08-01

    Full Text Available Freqüentemente a movimentação ortodôntica exige recursos adicionais de ancoragem. Os mini-parafusos têm-se apresentado como uma possível solução. O propósito deste trabalho foi estabelecer um método para a verticalização de molares inferiores inclinados para mesial, utilizando ancoragem em mini-parafusos colocados na região de linha oblíqüa externa da mandíbula. Foram selecionados três pacientes entre 40 a 48 anos (dois do gênero feminino, um do gênero masculino, com molares inferiores inclinados para mesial e distalmente posicionados às áreas edêntulas. Os pacientes foram tratados ortodonticamente durante um período de 6 a 12 meses, com técnica ortodôntica MD3. Mini-parafusos de titânio foram colocados bilateralmente com anestesia local. Uma incisão sobre a linha oblíqüa externa da mandíbula, medindo aproximadamente 1 cm foi realizada em cada lado, distalmente aos molares inclinados. Após descolamento muco-periosteal, mini-parafusos foram implantados e foram realizadas suturas deixando suas cabeças exteriorizadas. Uma semana após a remoção das suturas, cargas ortodônticas (entre 150 a 200 gramas/força foram aplicadas através de forças elásticas. Verificamos que alguma inflamação foi observada ao redor dos mini-parafusos, mas foi controlada com procedimentos de higienização. O procedimento cirúrgico é simples, podendo ser realizado pelo ortodontista; as formas dimensionais dos mini-parafusos são adequadas e estes são de fácil remoção após uso. Concluímos que o uso de mini-parafusos representa uma alternativa efetiva de ancoragem ortodôntica na verticalização de molares inferiores.Tooth movement frequently requires additional anchorage resources. Mini-screws have been used as a possible solution to this matter. The purpose of this study was to establish a method of mandibular molar uprighting, using mini-screw as anchorage, positioned on the mandibular external oblique line, behind and

  19. Contribution of Chlorophyll Fluorescence to the Apparent Reflectance of Vegetation

    Science.gov (United States)

    Campbell, P. K. Entcheva; Middleton, E. M.; Kim, M. S.

    2007-01-01

    Current strategies for monitoring the physiologic status of terrestrial vegetation rely on remote sensing reflectance (R) measurements, whi ch provide estimates of relative vegetation vigor based primarily on chlorophyll content. Vegetation chlorophyll fluorescence (CF) offers a non-destructive alternative and a more direct approach for diagnosis of vegetation stress before a significant reduction in chlorophyll content has occurred. Thus, monitoring of vegetation vigor based on CF may allow earlier stress detection and more accurate carbon sequestra tion estimates, than is possible using R data alone. However, the observed apparent vegetation reflectance (Ra) in reality includes contrib utions from both the reflected and fluoresced radiation. The aim of t his study is to determine the relative R and CF fractions contributing to Ra from the vegetation in the red to near-infrared region of the spectrum. The practical objectives of the study are to: 1) evaluate t he relationship between CF and R at the foliar level for corn, soybean, maple; and 2) for corn, determine if the relationship established f or healthy (optimal N) vegetation changes under N defiiency. To obtai n generally applicable results, experimental measurements were conducted on unrelated crop and tree species (maple, soybean and corn), unde r controlled conditions and a gradient of inorganic N fertilization l evels. Optical R spectra and actively induced CF emissions were obtained on the same foliar samples, in conjunction with measurements of p hotosynthetic function, pigment levels, and C and N content. The comm on spectral trends or similarities were examined. On average, 10-20% of apparent R at 685 nm was actually due to CF. The spectral trends in steady and maximum F varied significantly, with Fs (especially red) showing higher ability for species and treatment separation. The relative contribution of ChF to R varied significantly among species, with maple emitting much higher F amounts, as

  20. Sonographic Quantification of Ovarian Volumes in an adult Nigeria population

    OpenAIRE

    Dr. Nzotta Christian; Ugwu Anthony Chukwuka; Mr. Eze Joseph

    2009-01-01

    This study was conducted to establish the normal values of ovarian volumes in this locality. A convenience sample of 141 apparently and gynecologically healthy and non pregnant females was studied using transabdominal sonography. The length, width and anteroposterior dimensions of both the right and left ovaries were measured. Volumes of the ovaries were determined using the prolate ellipsoid formula. The mean ovarian volumes were found to be a 9.5cm3 and 10.cm3 for the right and left ovari...

  1. Restorasi mahkota logam dengan pasak fiber komposit pada molar permanen muda (Metal crown restoration with fiber composite post in young permanent molar

    Directory of Open Access Journals (Sweden)

    Theresia Dhearine Pratiwi

    2013-09-01

    Full Text Available Background: The first permanent molar has a high prevalence of caries with the most rapid progression in the first two years after eruption. The destruction can extend to the pulp and require endodontic treatment. After endodontic treatment the teeth should have a final restoration due to the possibilities of fracture. The teeth with a few remaining tissue need a restoration such as crown with post and core support. Fiber composite post is widely used today because it has a similar modulus elasticity as dentin. Purpose: The case report was aimed to share the endodontic treatment which was followed by fiber composite post and metal crown insertion on young permanent molar. Case: An 11 years old girls was referred to Pediatric Dentistry clinic at Universitas Indonesia Dental Hospital due to caries #36 that extend to the pulp. Case management: Endodontic treatment with metal crown supported by fiber composite post and composite core was done as final restoration. One month after procedure there was no subjective complaints or inflammation. Conclusion: The case report showed that endodontic treatment followed by fiber composite post and metal crown insertion could be done succesfully on young permanent molar of 11 years old patient.Latar belakang: Gigi molar pertama permanen muda (M1 merupakan gigi dengan angka kejadian karies yang tinggi dengan kerusakan paling cepat terjadi pada dua tahun pertama setelah gigi tersebut erupsi. Kerusakan tersebut dapat mencapai pulpa sehingga diperlukan perawatan endodontik. Gigi yang sudah dirawat memerlukan restorasi akhir yang baik, karena kemungkinan terjadi fraktur. Sisa jaringan gigi yang sedikit membutuhkan restorasi akhir berupa mahkota tiruan dengan dukungan pasak dan inti. Pasak fiber komposit merupakan pasak yang saat ini sering digunakan karena memiliki keunggulan modulus elastisitas yang menyerupai dentin. Tujuan: Tujuan penulisan laporan kasus ini adalah untuk melaporkan perawatan endodontik yang

  2. Two Qatari siblings with cystic fibrosis and apparent mineralocorticoid excess

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    Khalid Zahraldin

    2015-01-01

    Full Text Available Cystic fibrosis (CF and apparent mineralocorticoid excess (AME syndrome are both autosomal recessive disorders that result from mutations of specific identified genes for each condition. CF is caused by defects in the Cystic fibrosis trans membrane conductance regulator (CFTR gene which encodes for a protein that functions as a chloride channel and regulates the flow of other ions across the apical surface of epithelial cells. AME is due to the deficiency of 11β-hydroxysteroid dehydrogenase type 2 enzyme (11βHSD2, which is responsible for the peripheral inactivation of cortisol to cortisone. Cortisol excess stimulates the mineralocoritoid receptors (MR resulting in intense sodium retention, hypokalemia and hypertension. We report on a consanguineous Arab family, in which two sibs inherited both CF and AME. Gene testing for AME revealed previously unreported mutation in the 11βHSD2 gene. This report draws attention to the importance of recognizing the possibility of two recessive disorders in the same child in complex consanguineous families. Moreover, it provides a unique opportunity to highlight the implications of the coexistence of two genetic disorders on patient care and genetic counseling of the family.

  3. Estimating phosphorus concentrations following alum treatment using apparent settling velocity

    Science.gov (United States)

    Panuska, John; Robertson, Dale M.

    2009-01-01

    he apparent settling velocity (Vs) is a term used in empirical, steady-state, mass-balance lake models to represent the net phosphorus flux from the water column. The Vollenweider (1969) mixed-reactor lake model was rearranged and used to calculate Vs values for total phosphorus (TP) for three lakes treated with alum to reduce the internal flux of P to the water column (Delavan Lake, Wisconsin; Lake Morey, Vermont; and West Twin Lake, Ohio). An analysis of Vs values was conducted using data from these three lakes for both the pre- and post-alum treated conditions. Analysis of Vs values for both the pre- and post-alum conditions in Lake Morey and West Twin Lake resulted in a post-treatment mean Vs value of 7 ± 2.0 m·yr−1. The effect of the alum treatment, although short-lived in Delavan Lake, resulted in a mean post-treatment Vs value of 3.4 ± 0.3 m·yr−1. The consistency in the post-treatment Vs values in Lake Morey and West Twin Lake is used to demonstrate a predictive analysis method for water column TP concentrations in lakes following a successful treatment of the anoxic sediment area with alum. Additional pre- and post-alum in-lake and watershed loading data are needed to advance this concept into a management model.

  4. Severe cytomegalovirus infection in apparently immunocompetent patients: a systematic review

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    Varbobitis Ioannis C

    2008-03-01

    Full Text Available Abstract Background The morbidity and mortality associated with cytomegalovirus (CMV infection in immunocompromised patients (especially in HIV-infected patients and transplant recipients, as well as with congenital CMV infection are well known. In contrast, relatively little attention has been paid to the morbidity and mortality that CMV infection may cause in immunocompetent patients. Methods We reviewed the evidence associated with severe manifestations of CMV infection in apparently immunocompetent patients and the potential role of antiviral treatment for these infections. We searched in PubMed, Scopus, and the Cochrane Library for the period of 1950–2007 to identify relevant articles. Results We retrieved 89 articles reporting on severe CMV infection in 290 immunocompetent adults. Among these reports, the gastrointestinal tract (colitis and the central nervous system (meningitis, encephalitis, transverse myelitis were the most frequent sites of severe CMV infection. Manifestations from other organ-systems included haematological disorders (haemolytic anaemia, thrombocytopenia, thrombosis of the venous or arterial vascular system, ocular involvement (uveitis, and lung disease (pneumonitis. The clinical practice reported in the literature has been to prescribe antiviral treatment for the most severe manifestations of monophasic meningoencephalitis (seizures and coma, ocular involvement, and lung involvement due to CMV. Conclusion Severe life-threatening complications of CMV infection in immunocompetent patients may not be as rare as previously thought.

  5. Earth's Climate Sensitivity: Apparent Inconsistencies in Recent Assessments

    Science.gov (United States)

    Schwartz, Stephen E.; Charlson, Robert J.; Kahn, Ralph; Rodhe, Henning

    2014-12-01

    Earth's equilibrium climate sensitivity (ECS) and forcing of Earth's climate system over the industrial era have been re-examined in two new assessments: the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), and a study by Otto et al. (2013). The ranges of these quantities given in these assessments and also in the Fourth (2007) IPCC Assessment are analyzed here within the framework of a planetary energy balance model, taking into account the observed increase in global mean surface temperature over the instrumental record together with best estimates of the rate of increase of planetary heat content. This analysis shows systematic differences among the several assessments and apparent inconsistencies within individual assessments. Importantly, the likely range of ECS to doubled CO2 given in AR5, 1.5-4.5 K/(3.7 W m-2) exceeds the range inferred from the assessed likely range of forcing, 1.2-2.9 K/(3.7 W m-2), where 3.7 W m-2 denotes the forcing for doubled CO2. Such differences underscore the need to identify their causes and reduce the underlying uncertainties. Explanations might involve underestimated negative aerosol forcing, overestimated total forcing, overestimated climate sensitivity, poorly constrained ocean heating, limitations of the energy balance model, or a combination of effects.

  6. Apparent Optical Properties in Waters Influenced by the Mississippi River

    Science.gov (United States)

    D'Sa, E.; Miller, R. L.; McKee, B. A.; Trzaska, R.

    2002-01-01

    In-water downwelling irradiance (E(sub d)) and upwelling radiance (L(sub u)) were measured in coastal waters influenced by the Mississippi River at wavelengths corresponding to SeaWiFS spectral bands in April of 2000. Results of derived apparent optical properties (AOP's) such as spectral diffise attenuation coefficient for downwelling irradiance (K(sub d)) suggest that they are mainly influenced by phytoplankton chlorophyll. Large variations in chlorophyll concentrations (0.2 to greater than 10 mg per cubic meters) correspond to variations in K(sub d) at 443 nm ranging from about 0.1 to greater than 1.5 per meter. Attenuation values at 443 nm generally peaked (or were minimal at 555 nm) at depths where chlorophyll concentrations were high. Above water remote sensing reflectance R(sub rs) (443) derived from E(sub d) and L(sub u) shows good agreement to surface chlorophyll. Ratios of remote sensing reflectance, R(sub rs)(443/R(sub rs)(555)versus chlorophyll suggests a potential for obtaining a suitable bio-optical algorithm for the region influenced by the Mississippi River.

  7. Knoop Hardness - Apparent Yield Stress Relationship in Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Swab, Jeffrey J [ORNL; LaSalvia, Jerry [U.S. Army research Laboratory, Adelphi, MD; Wereszczak, Andrew A [ORNL; Strong, Kevin T [ORNL; Danna, Dominic [U.S. Army research Laboratory, Adelphi, MD; Ragan, Meredith E [ORNL; Ritt, Patrick J [ORNL

    2012-01-01

    In Tabor's classical studies of the deformation of metals, the yield stress (Y) and hardness (H) were shown to be related according to H/Y {approx} 3 for complete or fully plastic deformation. Since then it has been anecdotally shown for ceramics that this ratio is <3. Interest exists to explore this further so Hertzian indentation was used to measure the apparent yield stress of numerous ceramics and metals and their results were compared with each material's load-dependent Knoop hardness. The evaluated ceramics included standard reference materials for hardness (silicon nitride and tungsten carbide), silicon carbide, alumina, and glass. Several steel compositions were also tested for comparison. Knoop hardness measurements at 19.6 N (i.e., toward 'complete or fully plastic deformation'), showed that 2 < H/Y < 3 for the metals and 0.8 < H/Y < 1.8 for the glasses and ceramics. Being that H/Y {ne} 3 for the ceramics indicates that Tabor's analysis is either not applicable to ceramics or that full plastic deformation is not achieved with a Knoop indentation or both.

  8. Mixed quotation: The grammar of apparently transparent opacity

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    Emar Maier

    2014-05-01

    Full Text Available The phenomenon of mixed quotation exhibits clear signs of both the apparent transparency of compositional language use and the opacity of pure quotation. I argue that the interpretation of a mixed quotation in- volves the resolution of a metalinguistic presupposition. The leading idea behind my proposal is that a mixed-quoted expression, say, “has an anomalous feature”, means what x referred to with the words ‘has an anomalous feature’. To understand how this solves the paradox, I set up a precise grammatical framework, explicitly connecting various levels of linguistic analysis: phonological forms, categorial syntax, and a dynamic picture of the semantics–pragmatics interface. In this framework I formalize and evaluate a presuppositional account of mixed quotation. Finally, I address the phenomenon of unquotation and argue that it is an essential ingredient for an elegant and empirically adequate analysis of mixed quotation in natural language. http://dx.doi.org/10.3765/sp.7.7 BibTeX info

  9. Microlensing optical depth as a function of source apparent magnitude

    CERN Document Server

    Wood, Alexander

    2007-01-01

    Measurements of the microlensing optical depth, tau, towards the Galactic bulge appear to depend on the method used to obtain them. Those values based on the lensing of red clump giants (RCGs) appear to be significantly lower than those based on the lensing of all stars along the line of sight. This discrepancy is still not understood. Through Monte Carlo simulations, it is found that the discrepancy cannot be explained by a dependance on the flux limits of the two methods. The optical depth is expected to be generally constant as a function of source apparent magnitude for I_0 >~ 13.0, except in the range 13.5 <~ I_0 <~ 15.5. Here many RCGs are detected, causing a significant oscillation in tau. The amplitude of this oscillation is a function of the inclination angle of the Galactic bar, theta_bar, which may thus be constrained. A further constraint comes from a similar dependance of tau with theta_bar: combining the predicted trends with the measured values provides 1-sigma upper limits, which exclude...

  10. Evc regulates a symmetrical response to Shh signaling in molar development.

    Science.gov (United States)

    Nakatomi, M; Hovorakova, M; Gritli-Linde, A; Blair, H J; MacArthur, K; Peterka, M; Lesot, H; Peterkova, R; Ruiz-Perez, V L; Goodship, J A; Peters, H

    2013-03-01

    Tooth morphogenesis involves patterning through the activity of epithelial signaling centers that, among other molecules, secrete Sonic hedgehog (Shh). While it is known that Shh responding cells need intact primary cilia for signal transduction, the roles of individual cilia components for tooth morphogenesis are poorly understood. The clinical features of individuals with Ellis-van Creveld syndrome include various dental anomalies, and we show here that absence of the cilial protein Evc in mice causes various hypo- and hyperplasia defects during molar development. During first molar development, the response to Shh signaling is progressively lost in Evc-deficient embryos and, unexpectedly, the response consistently disappears in a buccal to lingual direction. The important role of Evc for establishing the buccal-lingual axis of the developing first molar is also supported by a displaced activity of the Wnt pathway in Evc mutants. The observed growth abnormalities eventually manifest in first molar microdontia, disruption of molar segmentation and symmetry, root fusions, and delayed differentiation. Analysis of our data indicates that both spatially and temporally disrupted activities of the Shh pathway are the primary cause for the variable dental anomalies seen in patients with Ellis-van Creveld syndrome or Weyers acrodental dysostosis.

  11. Efficacy of fentanyl transdermal patch in pain control after lower third molar surgery: A preliminary study

    Science.gov (United States)

    Vasovic, Miroslav; Andric, Miroslav; Todorovic, Ljubomir; Kokovic, Vladimir

    2016-01-01

    Background Surgical removal of impacted lower third molars is a common oral surgical procedure, generally followed by moderate to severe postoperative pain. Transdermal drug delivery as a concept offers interesting possibilities for postoperative pain control. The aim of this study was to evaluate the efficacy of transdermal system with fentanyl in relieving pain following impacted lower third molar surgery. Material and Methods Seventeen patients with bilateral impacted lower third molars were included in this preliminary study. For postoperative pain control, patients randomly received a fentanyl patch plus placebo tablet after the first operation and regular (placebo) patch and an analgesic, after the second operation. Analgesia was evaluated during first 24 hours postoperatively according to patients’ reports about time of first pain appearance and additional analgesic consumption. Pain severity was rated using a 10 cm long visual analogue scale (VAS). Results Intensity of postoperative pain and postoperative analgesic consumption were significantly lower after the Fentanyl Transdermal System (FTS) was applied (p<0.05). Duration of postoperative analgesia was significantly higher with FTS when compared to control treatment (p<0.05). Conclusions Based on the results of this preliminary study, transdermal system with fentanyl significantly reduced postoperative pain after third molar surgery. Key words:Analgesia, fentanyl, transdermal administration, third molar surgery, acute pain, postoperative care. PMID:27475691

  12. Mineralization of mandibular third molars can estimate chronological age--Brazilian indices.

    Science.gov (United States)

    de Oliveira, Fernando Toledo; Capelozza, Ana Lúcia Álvares; Lauris, José Roberto Pereira; de Bullen, Izabel Regina Fischer Rubira

    2012-06-10

    Forensic age estimation is an important element of anthropological research, as it produces one of the primary sources of data that researchers use to establish the identity of a person living or the identity of unknown bodily remains. The aim of this study was to determine if the chronology of third molar mineralization could be an accurate indicator of estimated age in a sample Brazilian population. If so, mineralization could determine the probability of an individual being 18 years or older. The study evaluated 407 panoramic radiographs of males and females from the past 5 years in order to assess the mineralization status of the mandibular third molars. The evaluation was carried out using an adaptation of Demirjian's system. The results indicated a strong correlation between chronological age and the mineralization of the mandibular third molars. The results indicated that modern Brazilian generation tends to demonstrate an earlier mandibular third molar mineralization than older Brazilian generation and people of other nationalities. Males reached developmental stages slightly earlier than females, but statistically significant differences between the sex were not found. The probability that an individual with third molar mineralization stage H had reached an age of 18 years or older was 96.8-98.6% for males and females, respectively.

  13. The chronological age estimation of third molar mineralization of Han population in southwestern China.

    Science.gov (United States)

    Qing, Maofeng; Qiu, Lihua; Gao, Zhi; Bhandari, Kishor

    2014-05-01

    The purpose of the study was to estimate the chronology of third molar mineralization in Han population of southwestern China and find its unique characteristics so that it would provide a reference in several legal cases like forensic age estimation. The study used Demirjian's staging method to study 2192 orthopantomograms of 984 male and 1208 female subjects aged between 8 and 25 years. The statistical data was analyzed by Student's t test and ANOVA. The conclusions of the study are: (1) The chronological mineralization age of third molars of Han population in Southwestern China is similar to the Turkish and the Japanese, was earlier than the Austrian and Han of South China, but later than the Spanish. (2) The mineralization timing of the third molars between two sides in maxilla or mandible has no significant differences in the same gender group. (3) There is no significant difference in mineralization of third molars between male and female, except for tooth 48 in Demirjian's stage E. (4) The mineralization of third molar in maxilla is earlier than mandible.

  14. Awareness of the Complications from Impacted Third Molar Surgeries among General Dental Practitioners

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    Farokh Farhadi

    2016-04-01

    Full Text Available Introduction: Surgery of impacted third molars and the resultant complications are common occurrences in dental offices. Therefore, the present study was undertaken to determine the awareness of general dental practitioners in Tabriz of complications of surgeries of impacted third molars. Materials and methods: In the present study a researcher-made questionnaire was completed by 186 randomly selected general dentists in Tabriz. After collecting the questionnaires and extractions of data, descriptive statistical methods and chi-squared test were used to evaluate the relationship between personal demographic variables (independent and the dependent variable of the study with SPSS 14. Statistical significance was set at P<0.05. Results: The mean ± standard deviation of the awareness of the subjects of complications of surgery of impacted third molars was 9.87±2.66, with minimum and maximum scores of 2 and 16, respectively. Of 186 dentists included in the study, 15 (8.1% had low awareness, 152 (81.7% had moderate awareness and 19 (10.2% had high awareness. Chi-squared test showed no significant relationship between awareness and other variables (age, gender and job experience (P>0.05. Conclusion: Based on the results, the awareness of general dental practitioners in Tabriz of the complications of impacted third molar surgeries was at a moderate level. Key words: Awareness; general dental practitioner; impacted third molar; complications;

  15. Bone resorption in incompletely impacted mandibular third molars and acute pericoronitis

    Directory of Open Access Journals (Sweden)

    Minoru Yamaoka

    2009-04-01

    Full Text Available Minoru Yamaoka, Yusuke Ono, Masahiro Takahashi, Ryosuke Doto, Kouichi Yasuda, Takashi Uematsu, Kiyofumi FurusawaMatsumoto Dental University, School of Dentistry, Shiojiri, Nagano, JapanAbstract: Acute pericoronitis (AP arises frequently in incompletely impacted mandibular third molars, but it remains unknown whether bone resorption in aging is associated with acute inflammation of the third molar. We conducted an experiment to compare the ratio of bone resorption to root length in the distal surface of the second molar (A, the proximal surface (B, and distal surface (C in mesio-angular, incompletely impacted third molars in 27 young and 58 older adults with AP and 77 young and 79 older adults without a history of AP. Bone resorption in A, B, and C in older adults with AP demonstrated a significantly higher ratio when compared to those without AP, whereas there was no difference between those with and without AP in young adults except for B in women. However, there were no differences between bone resorption in B with AP in young and older women, and between bone resorption in C with AP in young and older adults. These indicate that AP and bone resorption are associated with incompletely impacted mandibular third molars in older adults.Keywords: bone resorption, pericoronitis, mandible, acute inflammation, elderly

  16. The predictivity of mandibular third molar position as a risk indicator for pericoronitis.

    Science.gov (United States)

    Yamalik, Kemal; Bozkaya, Süleyman

    2008-03-01

    The aim of this study was to describe the characteristics of the mandibular third molar at highest risk for acute pericoronitis using clinical and radiographic analysis. A total of 102 volunteers, including 40 (39%) male and 62 (60%) female patients presenting with acute pericoronitis, participated in the study. The mean age of the participants was 23.4 years (range 17-30 years). The variables tested included the percentage of soft tissue coverage, availability of impinging maxillary dentition, and the angulation and eruption level of the mandibular third molar. While vertical impaction was the most frequent angulation (51%), horizontal impaction was quite rare (3%). Mesioangular impaction (25%) was slightly higher than distoangular impaction (21%). Difference between type of angulation was statistically significant for all groups (p pericoronitis was associated with the third molars that erupted at the same level of the adjacent tooth occlusal plane. The difference among the three levels of eruption was significant (p pericoronitis (41%). Evidence of impinging maxillary dentition did not have a statistically significant impact on presence of pericoronitis (p = 0.075). Mandibular third molars at or near to the same level of the occlusal plane of the arch and exhibiting vertical inclination were considered at highest risk for developing pericoronitis. Such third molars can be given high priority for prophylactic care due to the possibility of severe consequences of acute pericoronitis.

  17. Bone resorption in incompletely impacted mandibular third molars and acute pericoronitis.

    Science.gov (United States)

    Yamaoka, Minoru; Ono, Yusuke; Takahashi, Masahiro; Doto, Ryosuke; Yasuda, Kouichi; Uematsu, Takashi; Furusawa, Kiyofumi

    2009-01-01

    Acute pericoronitis (AP) arises frequently in incompletely impacted mandibular third molars, but it remains unknown whether bone resorption in aging is associated with acute inflammation of the third molar. We conducted an experiment to compare the ratio of bone resorption to root length in the distal surface of the second molar (A), the proximal surface (B), and distal surface (C) in mesio-angular, incompletely impacted third molars in 27 young and 58 older adults with AP and 77 young and 79 older adults without a history of AP. Bone resorption in A, B, and C in older adults with AP demonstrated a significantly higher ratio when compared to those without AP, whereas there was no difference between those with and without AP in young adults except for B in women. However, there were no differences between bone resorption in B with AP in young and older women, and between bone resorption in C with AP in young and older adults. These indicate that AP and bone resorption are associated with incompletely impacted mandibular third molars in older adults.

  18. Molar Incisor Hypomineralization: An Epidemiological Study with Prevalence and Etiological Factors in Indian Pediatric Population

    Science.gov (United States)

    Pandey, Ramesh K

    2016-01-01

    ABSTRACT Aims: To determine the prevalence of molar incisor hypomineralization (MIH) in Indian children and to analyze the possible etiological factors. Materials and methods: First permanent molars and all permanent incisors were examined in 1,369 children aged 8 to 12 years. Examinations were performed by two calibrated observers. The subjects were evaluated using judgment criteria proposed by Weerheijm et al in 2003. The parents accompanying children were given a questionnaire regarding pre- and postnatal history of the children. Results: A total of 191 children were diagnosed with MIH with a prevalence of 13.9%. Chi-square/Fisher exact test was used to compare the dichotomous variables. The relative risk with its 95% confidence interval was calculated to find the risk of clinical infections, such as chicken pox, jaundice, renal disorders, cardiac disorders, and affected molars with sex and type of delivery. Pre- and postnatal history of infection in a child was significantly correlated with the prevalence of MIH. Conclusion: The prevalence of MIH was 13.9% in the age group of 8 to 12 years. Prenatal and postnatal infections play an important role in hypomineralization of molars and incisors. How to cite this article: Mishra A, Pandey RK. Molar Incisor Hypomineralization: An Epidemiological Study with Prevalence and Etiological Factors in Indian Pediatric Population. Int J Clin Pediatr Dent 2016;9(2):167-171. PMID:27365942

  19. An evaluation of third molar eruption for assessment of chronologic age: A panoramic study

    Directory of Open Access Journals (Sweden)

    Monica Tuteja

    2012-01-01

    Full Text Available Objectives: The identity of a person can be established by assessing one′s age, and in order to be entitled to civil rights and social benefits, verification of the chronological age is required and thereby age estimation has gained an increasing significance in recent years. Tooth eruption is one of the criteria of developmental morphology that can be evaluated by either clinical examination or by evaluation of dental radiographs to determine the dental age. The present study was aimed to evaluate the reliability of the third molar eruption stage as a parameter for forensic age estimation in living subjects. Materials and Methods: The stage of wisdom tooth eruption in 77 male and 73 female Indian subjects aged between 12-26 years was determined by subjecting them to conventional orthopantomograms and was interpreted to assess the third molar eruption stages to evaluate the dental age. Results: Predicted minimum age and mean age of the study sample were found to be significant predictors (P<0.001 of actual age. Minimum age was able to explain 58.3% of the variation in actual age and the mean age was able to explain 60.3% of variation in actual age. Conclusion: Third molar is fairly a reliable indicator to determine the age of alveolar, gingival, and complete emergence of third molar in the occlusal plane in adolescents and young adults. Minimum and most probable ages of examined subjects can also be evaluated using third molar eruption stage.

  20. In vitro evaluation of an alternative method to bond molar tubes

    Directory of Open Access Journals (Sweden)

    Célia Regina Maio Pinzan-Vercelino

    2011-02-01

    Full Text Available Despite the advances in bonding materials, many clinicians today still prefer to place bands on molar teeth. Molar bonding procedures need improvement to be widely accepted clinically. OBJECTIVE: The purpose of this study was to evaluate the shear bond strength when an additional adhesive layer was applied on the occlusal tooth/tube interface to provide reinforcement to molar tubes. MATERIAL AND METHODS: Sixty third molars were selected and allocated to the 3 groups: group 1 received a conventional direct bond followed by the application of an additional layer of adhesive on the occlusal tooth/tube interface, group 2 received a conventional direct bond, and group 3 received a conventional direct bond and an additional cure time of 10 s. The specimens were debonded in a universal testing machine. The results were analyzed statistically by ANOVA and Tukey's test (α=0.05. RESULTS: Group 1 had a significantly higher (p0.05. CONCLUSIONS: The present in vitro findings indicate that the application of an additional layer of adhesive on the tooth/tube interface increased the shear bond strength of the bonded molar tubes.