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1

Partial Molar Volume of Helium Dissolved in Hydrogen  

NASA Astrophysics Data System (ADS)

We have determined the partial molar volume v ^' of helium dissolved in hydrogen, by analyzing existing data on the concentrations of the liquid and the coexisting vapor phase at high pressures. The partial molar volume can be found from the chemical potential of the helium in solution (v ^' =?2/ p |T,X2, where ?2 is the chemical potential of the helium in solution, and X2 its concentration), and the chemical potential can be determined from pressure and the concentration of the vapor phase, after applying virial corrections. Both v ^' and the virial terms lead to corrections to Henry's law. Over the range studied (0-50 bar and 15.5-29 K), we find that the partial molar volume of helium is equal to the molar volume of pure hydrogen, within a few percent. The results are relevant to recent experiment on the wetting of cesium by helium/hydrogen solutions, and may also have astrophysical applications.

Smith, Madeline; Pettersen, M. S.

2009-03-01

2

Partial molar volumes of amino acid derivatives in water  

Microsoft Academic Search

The partial molar volumes at infinite dilution for a number of hydrochlorides and sodium salts of N-methyl derivatives of a, ?-aminocarboxylic acids in water at 25°C are measured and related to their van der Waals volumes. Results indicate that 4.96±0.48 water molecules hydrate a betaine hydrochloride. Volumes of proton ionization and interaction terms are evaluated. Group contributions to the partial

Fereidoon Shahidi

1983-01-01

3

Partial molar volume of water in phonolitic glasses and liquids  

Microsoft Academic Search

The volumes and expansivities of four hydrous phonolite glasses and liquids have been measured by dilatometry from 300 K up to the glass transition and over a 50 K interval just above the glass transition. The partial molar volume of water is independent of the water content for the glass and liquid phases, with values of about 11.0ǂ.5 and 17.1ǂ.9

Ali M. Bouhifd; Alan Whittington; Pascal Richet

2001-01-01

4

Determination of partial molar volumes from free energy perturbation theory.  

PubMed

Partial molar volume is an important thermodynamic property that gives insights into molecular size and intermolecular interactions in solution. Theoretical frameworks for determining the partial molar volume (V°) of a solvated molecule generally apply Scaled Particle Theory or Kirkwood-Buff theory. With the current abilities to perform long molecular dynamics and Monte Carlo simulations, more direct methods are gaining popularity, such as computing V° directly as the difference in computed volume from two simulations, one with a solute present and another without. Thermodynamically, V° can also be determined as the pressure derivative of the free energy of solvation in the limit of infinite dilution. Both approaches are considered herein with the use of free energy perturbation (FEP) calculations to compute the necessary free energies of solvation at elevated pressures. Absolute and relative partial molar volumes are computed for benzene and benzene derivatives using the OPLS-AA force field. The mean unsigned error for all molecules is 2.8 cm(3) mol(-1). The present methodology should find use in many contexts such as the development and testing of force fields for use in computer simulations of organic and biomolecular systems, as a complement to related experimental studies, and to develop a deeper understanding of solute-solvent interactions. PMID:25589343

Vilseck, Jonah Z; Tirado-Rives, Julian; Jorgensen, William L

2015-04-01

5

Partial Molar Volumes for Lanthanide Sesquioxides in Sodium Silicate Melts  

NASA Astrophysics Data System (ADS)

Lanthanides are of great interest in igneous petrology as trace indicators of magmatic processes that control the origin and evolution of igneous rocks. A key to the petrogenetic modelling of magmatic processes and to determine the phase diagrams of lanthanide host phases is the accurate determination of the physico-chemical and thermodynamic properties of lanthanide-containing materials, such as the volumetric properties of lanthanide-bearing silicate melts. Therefore, we have undertaken to provide a new reliable volumetric data set for lanthanide-bearing silicate melts which allows the available models in the literature to be extended to lanthanide-bearing melts. For this purpose, the densities of various lanthanide-bearing silicate melts distributed along various pseudo-binary joins, where the end-members are Na-disilicate and one of the lanthanide sesquioxides (i.e., Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3), have been measured using the double-bob Archimedean method. The present results show that the addition of any lanthanide to Na-disilicate leads to an increase in the melt density and that the melt density increases with increasing atomic number of the lanthanide. From the present density data set, the molar volumes of these melts have been calculated and the partial molar volumes of each lanthanide sesquioxide in these melts have been determined using a linear regression through each pseudo-binary join (i.e., Na-disilicate - lanthanide sesquioxide). This study indicates ideal behaviour with respect to the molar volume (i.e., a linear variation of the molar volume along each pseudo-binary join) for Na-silicate melts containing up to 10 mol% of lanthanide oxide. Comparison between the partial molar volumes of lanthanide sesquioxides obtained in this study and the molar volumes of molten lanthanide sesquioxides given in the literature raise the possibility however that this ideality is not maintained along the entire Na-disilicate - lanthanide sesquioxide pseudo-binary joins. Excess volumes of mixing appear to be required to describe the combined volumetric data set.

Courtial, P.; Dingwell, D. B.

2004-12-01

6

Partial molar volumes of isoniazid solutions in aqueous-ethanol mixtures at 298.15 K  

NASA Astrophysics Data System (ADS)

Densities (?) of antitubercular drug isoniazid solutions in water, aqueous-ethanol (20-80 vol % EtOH) and in pure ethanol at 298.15 K with different molar concentrations (0.01-0.16 mol dm-3) were measured. Experimental density data were used to calculate apparent molar volumes (? v ) of isoniazid in different media. The ? v data were fitted to Massons relation and partial molar volumes (?{/v 0}) of drug for infinitely dilute solution were determined for each solution. Experimental and derived properties were interpreted in terms of drug-solvent molecular interactions and structural fittings in studied systems.

Deosarkar, S. D.; Sawale, R. T.; Tawde, P. D.; Kalyankar, T. M.

2015-02-01

7

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses  

NASA Astrophysics Data System (ADS)

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

8

Apparent molar and partial molar volumes of aqueous ceric ammonium nitrate solutions at 20, 25, 30, and 35°C  

NASA Astrophysics Data System (ADS)

Present paper reports the measured densities (?) and refractive indices ( n D) of aqueous solutions of ceric ammonium nitrate (CAN) at 20, 25, 30, and 35°C in different concentrations of solution. Apparent molar volumes (?v) have been calculated from the density data at different temperatures and fitted to Massons relation to get limiting partial molar volumes (?{v/0}) of CAN. Refractive index data were fitted to linear dependence over concentration of solutions and values of constant K and n {D/0} for different temperatures were evaluated. Specific refractions ( R D) of solutions were calculated from the refractive index and density data. Concentration and temperature effects on experimental and derived properties have been discussed in terms of structural interactions.

Deosarkar, S. D.; Wanale, S. G.; Shelke, M. P.

2014-07-01

9

Note: Nonpolar solute partial molar volume response to attractive interactions with water  

SciTech Connect

The impact of attractive interactions on the partial molar volumes of methane-like solutes in water is characterized using molecular simulations. Attractions account for a significant 20% volume drop between a repulsive Weeks-Chandler-Andersen and full Lennard-Jones description of methane interactions. The response of the volume to interaction perturbations is characterized by linear fits to our simulations and a rigorous statistical thermodynamic expression for the derivative of the volume to increasing attractions. While a weak non-linear response is observed, an average effective slope accurately captures the volume decrease. This response, however, is anticipated to become more non-linear with increasing solute size.

Williams, Steven M.; Ashbaugh, Henry S., E-mail: hanka@tulane.edu [Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118 (United States)

2014-01-07

10

Determination Of Partial Molar Volumes Of Iron Species In Silicate Melts  

NASA Astrophysics Data System (ADS)

One of the major questions of planetary geology is the composition and conditions of the Earth interior. Magmas are among our most important windows into the interior. Iron, being a major element with multiple valence states, is an important influence on redox state. One way to investigate redox state is via a volume equation of state. Density data are used in computing partial molar volumes, which may then be used to construct a volume equation of state. We have devised an apparatus which permits high-quality density measurements in silicate melts at high temperatures (up to ?1500 °C) and reduced oxygen fugacity at atmospheric pressure using the Archimedean single-bob method. With this apparatus, we have collected the first high-quality density data of iron-bearing silicate melts which had their iron predominately as ferrous. We measured the density of Columbia River Basalt (approximate temperature range: 1250 °C -- 1450 °C) and an artificial composition in the FeO-FeO1.5-CaO-SiO2 system (?1460 °C) at the oxygen fugacity corresponding to the Iron-Wüstite buffer. We used these data in conjunction with literature density data gathered at thermodynamic equilibrium to calculate the partial molar volume of the iron species as a function of temperature at standard pressure. We speciated iron according to: 0.4 FeO + 0.6 FeO1.5 ? FeO1.3 The partial molar volumes of FeO, FeO1.5, and FeO1.3 were fit well with no compositional dependence, despite the wide range of compositions included in this study. To the extent that melt structure can be inferred from partial molar volumes, this result suggests that there is no compositional dependency to the structure of any of these iron species. Our partial molar volumes of FeO and FeO1.5 are consistent within one standard error of those found by Lange & Carmichael (1987) and Ghiorso & Kress (2004). However, our partial molar volume for FeO1.3 at reference temperature was one-third that of Ghiorso & Kress (2004) (Lange & Carmichael (1987) did not include this species in their fit), which would result in greater conversion of FeO and FeO1.5 into FeO1.3 at pressure.

Dwyer, C. A.; Kress, V. C.

2009-12-01

11

Fluctuation-based computer calculation of partial molar properties. I. Molecular dynamics simulation of constant volume fluctuations  

Microsoft Academic Search

Partial molar volumes, energies, and enthalpies are calculated via the (N,U,V) molecular dynamics implementation of their corresponding operational definitions in terms of constant volume fluctuations. The method is exact for the former property but only approximate for the latter two. The partial molar volume operational definition satisfies Euler’s homogeneous function theorem identically. The corresponding energy definition is based upon a

Pablo G. Debenedetti

1987-01-01

12

Partial molar volumes and activity coefficients of the water in aqueous polyol solutions and the osmotic pressures of these solutions  

Microsoft Academic Search

The freezing-point depression and density of aqueous polyol (alditol) solutions were measured, and the osmotic pressure and\\u000a the partial molar volume of the water of these solutions were calculated. The osmotic pressures calculated from the freezing-point\\u000a depression data were compared with those calculated with van't Hoff's equation and fairly good agreement was found. The partial\\u000a molar volumes of the water

Keitaro Kiyosawa

1992-01-01

13

Determination of Partial Molar Volume of Ferrous Iron in Silicate Melts  

NASA Astrophysics Data System (ADS)

The density of silicate liquids and partial molar volumes of oxide components have been a topic of intense study over several decades. Nevertheless, only a handful of density measurements have been performed in ferrous- iron dominated melts. Ferrous iron is among the most important elements in the crust and mantle. Knowledge of the partial molar volume of ferrous iron is critical to calculating phase saturation, exchange equilibrium, density etc. in major rock-forming phases as a function of pressure. We have developed a protocol for measuring density of silicate melts under reducing conditions using a single-bob Archimedean device. We are currently performing density measurements in the CaO-FeO-Al2O3-SiO2 system with the goal of accurately constraining the partial molar volume of ferrous iron as a function of temperature and composition. The device as currently configured uses a Mo crucible and Mo bob assembly. Preliminary work in mildly reducing melts suggest that up to 3 mol% Mo oxide in the silicate melt can coexist with Mo metal. On quench, Mo comes out of solution forming globular "micro-nuggets" and/or dendritic crystals. Under more reducing conditions in Fe-rich compositions, Fe in the silicate reacts with Mo metal to form "micro-nuggets" of equilibrium immiscible Fe-Mo liquid alloy. We believe that under these conditions the Fe content of the melt and the formation of "micro-nuggets" are governed by the reactions: \\begin{eqnarray} {Mo(s) + \\frac{y}{2} O2 \\ (g)} &?& {MoO y \\ ( silicate \\ melt) ? Mo( alloy) + \\frac{y}{2} O2 \\ (g)}\

Dwyer, C. A.; Kress, V. C.

2007-12-01

14

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

15

Reply to ``Comment on `Hydrophobic effects on partial molar volume' '' [J. Chem. Phys. 123, 167103 (2005)  

NASA Astrophysics Data System (ADS)

In the Comment on our paper [J. Chem. Phys. 123, 167103 (2005), preceding paper], Graziano argues based on the scaled particle theory that the partial molar volume change in the transfer of a hydrophobic solute from "hypothetical nonpolar water" to water can be explained simply by the difference in the effective size of solvent molecules. Opposing to the argument, we clarify using the reference interaction site model theory that the attractive interactions represented by the hydrogen bonding play an essential role for the volume change, and that the explanation given by Graziano replaces the real physics by a fake model based on an "effective" molecular diameter. We also make a general argument against the use of hard-sphere models when one considers the properties of hydration.

Imai, Takashi; Hirata, Fumio

2005-10-01

16

Quadrupole terms in the Maxwell equations: Born energy, partial molar volume, and entropy of ions.  

PubMed

A new equation of state relating the macroscopic quadrupole moment density Q to the gradient of the field ?E in an isotropic fluid is derived: Q = ?Q(?E - U?·E/3), where the quadrupolarizability ?Q is proportional to the squared molecular quadrupole moment. Using this equation of state, a generalized expression for the Born energy of an ion dissolved in quadrupolar solvent is obtained. It turns out that the potential and the energy of a point charge in a quadrupolar medium are finite. From the obtained Born energy, the partial molar volume and the partial molar entropy of a dissolved ion follow. Both are compared to experimental data for a large number of simple ions in aqueous solutions. From the comparison the value of the quadrupolar length LQ is determined, LQ = (?Q/3?)(1/2) = 1-4 Å. Data for ion transfer from aqueous to polar oil solution are analyzed, which allowed for the determination of the quadrupolarizability of nitrobenzene. PMID:24559353

Slavchov, Radomir I; Ivanov, Tzanko I

2014-02-21

17

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

PubMed

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. PMID:25681917

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

2015-02-14

18

Why Is the Partial Molar Volume of CO2 So Small When Dissolved in a Room Temperature Ionic Liquid? Structure and  

E-print Network

Why Is the Partial Molar Volume of CO2 So Small When Dissolved in a Room Temperature Ionic Liquid is dissolved in an ionic liquid, its partial molar volume is much smaller than that observed in most other and dynamics occurring across the boundary of the CO2 ionic liquid interface. We find that the liquid structure

Berne, Bruce J.

19

Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections  

E-print Network

Molecular Density Functional Theory (MDFT) offers an efficient implicit- solvent method to estimate molecule solvation free-energies whereas conserving a fully molecular representation of the solvent. Even within a second order ap- proximation for the free-energy functional, the so-called homogeneous reference uid approximation, we show that the hydration free-energies computed for a dataset of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by two to three orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canoni- cal to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justifcation to empirical partial molar volume corrections that have been proposed recently.

Volodymyr P. Sergiievskyi; Guillaume Jeanmairet; Maximilien Levesque; Daniel Borgis

2014-06-11

20

Partial Molar Volumes of Components and Species in O-S-Fe-Ni Oxide and Sulfide Liquids  

NASA Astrophysics Data System (ADS)

High-quality thermochemical models are now available for sulfide liquids at one bar pressure. An accurate description of the volume mixing properties of these liquids is required in order to apply these one-bar models to important problems at elevated pressure, including sulfide-hosted ore formation, sulfur cycling in convergent margin settings and core formation. Our experimental data have been combined with select density data from other laboratories to calibrate a comprehensive model for density and partial molar volumes of liquids in the O-S- Fe-Ni system. Our results indicate significant negative deviation from linear mixing across the Fe-S, Ni-S and Cu-S binaries. This result is in qualitative agreement with those from prior studies. In the context of associated homogeneous speciation models for sulfide liquids (Kress, 2000, 2007), this negative volume of mixing can be interpreted as a strongly negative volume of reaction for the formation for intermediate melt species from end member elemental components (? Vf). Our regression yields ? Vf values of -6.2, -9.4 and -9.1 cc/mol for FeS, NiS and CuS respectively. There is insufficient oxygen in experimental liquids to resolve a composition dependence for v¯O, but the unrealistic negative regressed value for oxygen partial molar volume suggests a negative ? Vf for FeO and FeO1.5. Partial molar volumes of Fe, Ni and Cu liquid species are calculated from Nash and Steinemann (1995). All other v¯i are assumed to be linear mixtures of component species volumes. This assumption also implies a moderate negative ? Vf for the species in question. The resulting model reproduces experimental densities from our laboratory with a 3.6% average error. This is comparable to the estimated measurement error. The larger 5.1% error for the full data set can be attributed to lower precision in some of the other studies and the effects of inter-laboratory error. The sulfide volume model can be applied to calculate thermochemical properties of sulfide liquids to moderate pressures. This model is used in conjunction with literature experiments on coexisting sulfide and silicate liquids at pressure to explore complex interactions between the pressure dependences of oxygen fugacity, sulfur fugacity and sulfide saturation.

Kress, V. C.

2007-12-01

21

Standard partial molar volumes of some aqueous alkanolamines and alkoxyamines at temperatures up to 325 degrees C: functional group additivity in polar organic solutes under hydrothermal conditions.  

PubMed

Apparent molar volumes of dilute aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N,N-dimethylethanolamine (DMEA), ethylethanolamine (EAE), 2-diethylethanolamine (2-DEEA), and 3-methoxypropylamine (3-MPA) and their salts were measured at temperatures from 150 to 325 degrees C and pressures as high as 15 MPa. The results were corrected for the ionization and used to obtain the standard partial molar volumes, Vo2. A three-parameter equation of state was used to describe the temperature and pressure dependence of the standard partial molar volumes. The fitting parameters were successfully divided into functional group contributions at all temperatures to obtain the standard partial molar volume contributions. Including literature results for alcohols, carboxylic acids, and hydroxycarboxylic acids yielded the standard partial molar volume contributions of the functional groups >CH-, >CH2, -CH3, -OH, -COOH, -O-, -->N, >NH, -NH2, -COO-Na+, -NH3+Cl-, >NH2+Cl-, and -->NH+Cl- over the range (150 degrees C partial molar volume of aqueous organic solutes composed of these groups at temperatures up to approximately 310 degrees C and pressures of 10-20 MPa to within a precision of +/-5 cm3 x mol(-1). The model could not be extended to higher temperatures because of uncertainties caused by thermal decomposition. At temperatures above approximately 250 degrees C, the order of the group contributions to Vo2 changes from that observed at 25 degrees C, to become increasingly consistent with the polarity of each functional group. The effect of the dipole moment of each molecule on the contribution to Vo2 from long-range solvent polarization was calculated from the multipole expansion of the Born equation using dipole moments estimated from restricted Hartree-Fock calculations with Gaussian 03 (Gaussian, Inc., Wallingford, CT) and the Onsager reaction-field approximation for solvent effects. Below 325 degrees C, the dipole contribution was found to be less than 2 cm3 x mol(-1) for all the solute molecules studied. At higher temperatures and pressures near steam saturation, the effect is much larger and may explain anomalies in functional group additivity observed in small, very polar solutes. PMID:18412415

Bulemela, E; Tremaine, Peter R

2008-05-01

22

Towards a universal method for calculating hydration free energies: a 3D reference interaction site model with partial molar volume correction  

NASA Astrophysics Data System (ADS)

We report a simple universal method to systematically improve the accuracy of hydration free energies calculated using an integral equation theory of molecular liquids, the 3D reference interaction site model. A strong linear correlation is observed between the difference of the experimental and (uncorrected) calculated hydration free energies and the calculated partial molar volume for a data set of 185 neutral organic molecules from different chemical classes. By using the partial molar volume as a linear empirical correction to the calculated hydration free energy, we obtain predictions of hydration free energies in excellent agreement with experiment (R = 0.94, ? = 0.99 kcal mol - 1 for a test set of 120 organic molecules).

Palmer, David S.; Frolov, Andrey I.; Ratkova, Ekaterina L.; Fedorov, Maxim V.

2010-12-01

23

New Measurements of the Densities of Copper- and Nickel-Sulfide Liquids and Preliminary Estimates of the Partial Molar Volumes of Cu, Ni, S and O  

NASA Astrophysics Data System (ADS)

We present the results of density measurements in Ni- and Cu-sulfide liquids. Density measurements were performed in-situ at 1250° C under controlled-atmosphere conditions using the modified single-bob (MSB) Archimedean method. The MSB consists of a ~2 mm diameter rod with a ~6 mm long ~7 mm diameter cylindrical bob attached ~7 mm from the base of the rod. The bob and crucible were constructed from Yt stabilized zirconia to minimize reaction with the corrosive sulfide liquid. Zirconia density at temperature was calibrated against the known density of molten Cu metal (Drotning 1981, High Temp-High Press 13: 441-458). Density was determined by measuring buoyancy as a function of immersed volume. Buoyancy was measured with a 0.1 mg resolution analytical balance interfaced with a computer. The crucible is mounted on a micrometer "elevator" allowing regulation of immersion with .005 mm resolution. Temperature was measured with an S-type thermocouple in contact with the bottom of the crucible. We explored log(fO2) from -8.2 to -12.6 and log(fS2) from -1.9 to -3.3. Five measurements have been made so far. Cu-sulfide densities range from 6.32 to 6.36 g/cc and were reproducible to +/-0.7%. Measured Ni-sulfide densities were lower, ranging from 5.27 to 5.79 g/cc. Wetting problems in Ni-sulfide compositions made these measurements more difficult. Reproducibility in Ni-sulfide melts was roughly +/-5%. Measured density values were used to regress preliminary partial molar volumes of sulfide liquids in the Cu-Ni-S-O system. A linear least squares fit was derived from the five density measurements along with the densities of pure molten Cu (Drotning 1981, ibid.) and Ni (Nasch 1995, Phys Chem Liq 29: 43-58) at 1250° C. Melt compositions under experimental conditions were estimated using the thermodynamic model of Kress (submitted). The molar volume of the system (V) can be expressed as: V = 8.18 XCu + 7.38 XNi + 30.33 XS where XI is the mole fraction of component i. Oxygen contents were too low to estimate the partial molar volume of this component.

Kress, V. C.; Ghiorso, M. S.

2001-12-01

24

Variation and decomposition of the partial molar volume of small gas molecules in different organic solvents derived from molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

The partial molar volumes, bar V_i, of the gas solutes H2, CO, and CO2, solvated in acetone, methanol, heptane, and diethylether are determined computationally in the limit of infinite dilution and standard conditions. Solutions are described with molecular dynamics simulations in combination with the OPLS-aa force field for solvents and customized force field for solutes. bar V_i is determined with the direct method, while the composition of bar V_i is studied with Kirkwood-Buff integrals (KBIs). Subsequently, the amount of unoccupied space and size of pre-formed cavities in pure solvents is determined. Additionally, the shape of individual solvent cages is analyzed. Calculated bar V_i deviate only 3.4 cm3 mol-1 (7.1%) from experimental literature values. Experimental bar V_i variations across solutions are reproduced qualitatively and also quantitatively in most cases. The KBI analysis identifies differences in solute induced solvent reorganization in the immediate vicinity of H2 (<0.7 nm) and solvent reorganization up to the third solvation shell of CO and CO2 (<1.6 nm) as the origin of bar V_i variations. In all solutions, larger bar V_i are found in solvents that exhibit weak internal interactions, low cohesive energy density and large compressibility. Weak internal interactions facilitate solvent displacement by thermal solute movement, which enhances the size of solvent cages and thus bar V_i. Additionally, attractive electrostatic interactions of CO2 and the solvents, which do not depend on internal solvent interactions only, partially reversed the bar V_i trends observed in H2 and CO solutions where electrostatic interactions with the solvents are absent. More empty space and larger pre-formed cavities are found in solvents with weak internal interactions, however, no evidence is found that solutes in any considered solvent are accommodated in pre-formed cavities. Individual solvent cages are found to be elongated in the negative direction of solute movement. This wake behind the moving solute is more pronounced in case of mobile H2 and in solvents with weaker internal interactions. However, deviations from a spherical solvent cage shape do not influence solute-solvent radial distribution functions after averaging over all solvent cage orientations and hence do not change bar V_i. Overall, the applied methodology reproduces bar V_i and its variations reliably and the used bar V_i decompositions identify the underlying reasons behind observed bar V_i variations.

Klähn, Marco; Martin, Alistair; Cheong, Daniel W.; Garland, Marc V.

2013-12-01

25

Management of a partial molar pregnancy: a case study report.  

PubMed

Partial molar pregnancy with coexisting fetus is a rare complication of pregnancy and carries significant risks to both the mother and the fetus. Maternal risks include abnormal bleeding and the development of preeclampsia. The fetus frequently develops abnormally, often due to abnormal karyotype. This case presents a woman with a partial molar pregnancy with coexisting fetus, including diagnosis, plan of care, and delivery information. PMID:19474581

Drummond, Susan; Fritz, Elizabeth

2009-01-01

26

Anesthetic implications of a partial molar pregnancy and associated complications.  

PubMed

In the United States, molar pregnancy occurs between 1 in 1,200 and 1 in 2,500 pregnancies. The critical nature of complications associated with a molar pregnancy requires advanced perioperative anesthetic management. This case report details the perioperative events of a 34-year-old gravida 5, para 3, with a partial molar pregnancy who underwent general anesthesia for a dilatation and curettage procedure, following therapeutic termination of a coexisting fetus at 18 weeks' gestation. Her initial presentation, anesthetic and operative management, and postoperative course are described clearly. The medical and anesthetic interventions required for treatment of molar pregnancy are reviewed. Of molar pregnancies, 80% are uncomplicated and follow an unremarkable course. However, for the remaining 20%, complications can be severe and may lead to substantial morbidity and mortality in otherwise healthy women. PMID:11759139

Celeski, D; Micho, J; Walters, L

2001-02-01

27

Oxygen from Hydrogen Peroxide. A Safe Molar Volume-Molar Mass Experiment.  

ERIC Educational Resources Information Center

Describes a molar volume-molar mass experiment for use in general chemistry laboratories. Gives background technical information, procedures for the titration of aqueous hydrogen peroxide with standard potassium permanganate and catalytic decomposition of hydrogen peroxide to produce oxygen, and a discussion of the results obtained in three…

Bedenbaugh, John H.; And Others

1988-01-01

28

40 CFR Table 1 to Subpart Ja of... - Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents  

Code of Federal Regulations, 2014 CFR

...Environment 7 2014-07-01 2014-07-01 false Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents 1 Table...Ja, Table 1 Table 1 to Subpart Ja of Part 60—Molar Exhaust Volumes and Molar Heat Content of Fuel...

2014-07-01

29

40 CFR Table 1 to Subpart Ja of... - Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents  

Code of Federal Regulations, 2013 CFR

...Environment 7 2013-07-01 2013-07-01 false Molar Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents 1 Table...Ja, Table 1 Table 1 to Subpart Ja of Part 60—Molar Exhaust Volumes and Molar Heat Content of Fuel...

2013-07-01

30

Density and sound speed measurements on model basalt (An-Di-Hd) liquids at one bar: New constraints on the partial molar volume and compressibility of the FeO component  

NASA Astrophysics Data System (ADS)

Density and sound speed measurements were obtained over a wide range of temperature for three model basalt liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system. High-temperature (1585-1838 K) double-bob density measurements were combined with low-temperature (943-930 K) measurements at the limiting fictive temperature for each sample to provide liquid volume data over a temperature interval of ?900 K. In addition, relaxed sound speeds were obtained with a frequency sweep acoustic interferometer from 1665-1876 K. An ideal mixing model for molar volume, thermal expansivity, and isothermal compressibility recovers the new data from this study and leads to the following fitted values (±2?) at 1723 K for VbarFeO (12.86±0.32 cm/mol), ?VbarFeO/?T((3.69±1.16)×10-3 cm/mol-K) and ?barT,FeO((4.72±0.46)×10-2 GPa). These volumetric properties for the FeO component are estimated to reflect Fe2+ in an average coordination of 5.7 (±0.2), based on the relationship between VbarFeO and Fe2+ coordination derived by a comparison to mineral molar volumes (Guo et al., 2013). Application of these volumetric data to a calculation of the pressure dependence of the Fe-Mg exchange reaction between orthopyroxene and basaltic liquid results in a small decrease in Fe-MgKD with pressure. In contrast, partial melting experiments of peridotite show a small increase in Fe-MgKD(opx-liq) with pressure (e.g., Walter, 1998). This difference in the pressure dependence is proposed to reflect the role of alkalis in reducing the average coordination number of Fe2+ toward five compared to the alkali-free model basalt compositions in this study, thus changing the volume and compressibility of the FeO liquid component. The results from this study may be most appropriately applied to lunar basalts, which are impoverished in alkalis.

Guo, Xuan; Lange, Rebecca A.; Ai, Yuhui

2014-02-01

31

Correlations between elastic moduli and molar volume in metallic glasses  

SciTech Connect

We report clear correlations between bulk modulus (K) and average molar volume V{sub m}, and between Poisson's ratio {nu} and V{sub m} for various bulk metallic glasses. The origin for the correlations between elastic moduli and V{sub m} are discussed. The established correlation, associated with Poisson's ratio {nu}, and since the {nu} correlates with plasticity of metallic glasses, indicates that the average molar volume is important factor to be considered for plastic metallic glasses searching. The found correlations also suggest a close relation between the mechanical properties and the short-range atomic bonding, and assist in understanding deformation behavior in metallic glasses.

Wang, J. Q.; Wang, W. H.; Yu, H. B.; Bai, H. Y. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2009-03-23

32

Reduced radiation-absorbed dose to tissues with partial panoramic radiography for evaluation of third molars  

SciTech Connect

The radiation-absorbed doses from panoramic radiography, distal molar radiography, and a partial panoramic radiographic technique that exposes only the third molar region to radiation are compared. Doses of radiation to the submandibular salivary gland were comparable by all three techniques, but doses of radiation to the head and neck were reduced greatly by the partial panoramic radiographic technique. Partial panoramic radiography is a diagnostically satisfactory and a radiologically safer technique for evaluation of third molar pathosis than is panoramic or distal molar radiography.

Kircos, L.T.; Eakle, W.S.; Smith, R.A.

1986-05-01

33

Molar volumes of molten indium at high pressures measured in a diamond Guoyin Shen,a)  

E-print Network

Molar volumes of molten indium at high pressures measured in a diamond anvil cell Guoyin Shen for publication 18 June 2002 Molar volumes of molten indium have been measured in an isothermal compression up the molar volume of amorphous materials in a DAC and report the results on molten indium in an isothermal

Shen, Guoyin

34

Excess molar volumes and excess molar enthalpies of quinoline + aromatic hydrocarbons at 303. 15 K  

SciTech Connect

Excess molar volumes V[sub m][sup E] and excess molar enthalpies H[sub m][sup E][sub m] for quinoline + benzene, toluene, o-xylene, or p-xylene for the whole range of compositions have been measured at 303.15 K. The values of H[sub m][sup E] and V[sub m][sup E] for these mixtures suggest that quinoline is partly self-associated and there is strong interaction (weak hydrogen bonding) between quinoline and aromatic hydrocarbons. The values of V[sub m][sup E] and H[sub m][sup E] have also been computed from the Flory and Abe theory and Sanchez and Lacombe theory as well as from the Graph theory. All the theories correctly predict the sign or magnitude of H[sub m][sup E]. Only the Graph theory is able to predict correctly the sign or magnitude of V[sub m][sup E]; the other theories give a poor estimate of V[sub m][sup E].

Kalra, K.C.; Singh, K.C.; Spah, D.C.; Batra, R.; Maken, S. (Maharshi Dayanand Univ., Rohtak (India). Dept. of Chemistry)

1993-01-01

35

The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses  

SciTech Connect

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.

Reynolds, Jacob G. [Washington River Protection Solutions, Richland, WA (United States)

2013-01-11

36

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  

Microsoft Academic Search

Ultrasonic velocities, u, densities, ?, 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=308.15K. Using the experimental results, the excess molar volume, VmE, partial molar volumes, V¯m,1, V¯m,2, and excess partial molar volumes, V¯m,1E,

M. Kondaiah; D. Sravana Kumar; K. Sreekanth; D. Krishna Rao

2011-01-01

37

The partial molar sound speed of TiO2 in sodium silicate melts: Evidence for an exceptionally compressible component  

NASA Astrophysics Data System (ADS)

Longitudinal acoustic velocities were measured at one bar by an ultrasonic frequency sweep acoustic interferometer for ten Na2O-TiO2-SiO2 (NTS) liquids for which previous density and thermal expansion measurements were made (Liu and Lange, 2001). This previous study showed that the partial molar volume of the TiO2 component varied systematically with composition and reflected changes in the average coordination of Ti4+ from values of ~4.6 to ~5.4. Sound speed data were collected at frequencies of 4.5, 5, and 6 MHz between 1233 and 1896 K; in all cases, the sound speeds decrease with increasing temperature. Six of the liquids share a similar (~25 mol%) TiO2 concentration, so that the effect of varying Na:Si ratio on the partial molar sound speed of the TiO2 component can be evaluated. The results for these ten NTS liquids were combined with sound speed data on Na2O-SiO2 liquids from the literature to derive the partial molar sound speed of the TiO2 component in these liquids. The results show that, at 1573 K, it is inversely correlated with SiO2 concentration, from values as low as 571±56 m/s to those as high as 1235±54 m/s, a variation of more than 100%. Fitted values for the partial molar sound speeds of the SiO2 and Na2O components at 1573 K are constants at 2538±52 and 2713±52 m/s, respectively. When the sound speed data are combined with density data to calculate melt compressibility, the results show that the TiO2 component is 3-15 more compressible than either the Na2O or SiO2 component. The partial molar compressibility of the TiO2 component is also strongly correlated to its partial molar thermal expansivity. It is shown that the TiO2 component is most compressible and most expansive when the average Ti4+ coordination in these sodium silicate liquids is near five, which strongly suggests that the abundance of five-coordinated Ti4+ enhances topological mechanisms of both compression and thermal expansion.

Liu, Q.; Ai, Y.; Lange, R. A.

2005-12-01

38

Density, partial, and excess volumes of solutions of methacrylic acid in organic solvents at 293 K  

NASA Astrophysics Data System (ADS)

The densities of solutions of methacrylic acid in acetonitrile, benzene, hexane, 1,2-dichloroethane, and acetic acid at a temperature of 293 K and atmospheric pressure are determined by means of pycnometry. The values of the excess molar volume for the studied systems and those of the partial molar volumes of the components are calculated. It is found that the excess molar volume of binary systems of methacrylic acid with benzene, hexane, 1,2-dichloroethane, and acetic acid is positive over the range of concentrations and is negative in the methacrylic acid-acetonitrile system.

Sergeev, V. V.; Van-Chin-Syan, Yu. Ya.

2015-03-01

39

Sealing versus partial caries removal in primary molars: a randomized clinical trial  

PubMed Central

Background The resin-based pit and fissure sealant is considered a successful tool in caries prevention, however there is a growing evidence of its use in controlling already established caries in posterior teeth. The aim of this clinical trial is to verify the efficacy of pit and fissure sealants in arresting dentinal caries lesions compared to partial excavation and restorative treatment in primary molar teeth. Methods Thirty six patients with occlusal cavitated primary molar reaching outer half of dentin were selected. The patients were randomly allocated into two groups: sealant application (experimental group – n?=?17) and restoration with composite resin (control group – n?=?19). Clinical and radiograph evaluation were performed after 6, 12 and 18 months. The chi-square test was used to verify the distribution of characteristics variables of the sample among the groups. The survival rate of treatments was evaluated using Kaplan–Meier survival and log-rank test. Fisher’s Exact and logistic regression tests were calculated in each evaluation period (??=?5%). Results The control group showed significantly better clinical survival after 18 months (p?=?0.0025). In both groups, no caries progression was registered on the radiographic evaluations. Conclusions Sealing had similar efficacy in the arrestment of caries progression of cavitated occlusal lesions compared to partial excavation of the lesions, even though the frequency of re-treatments was significantly higher in sealed lesions. Trial registration Registro Brasileiro de Ensaios Clínicos (ReBEC): RBR-9kkv53 PMID:24884684

2014-01-01

40

Changes in Apparent Molar Water Volume and DKP Solubility Yield Insights on the Hofmeister Effect  

PubMed Central

This study examines the properties of a 4 × 2 matrix of aqueous cations and anions at concentrations up to 8.0 M. The apparent molar water volume, as calculated by subtracting the mass and volume of the ions from the corresponding solution density, was found to exceed the molar volume of ice in many concentrated electrolyte solutions, underscoring the non-ideal behavior of these systems. The solvent properties of water were also analyzed by measuring the solubility of diketopiperazine (DKP) in 2.000 M salt solutions prepared from the same ion combinations. Solution rankings for DKP solubility were found to parallel the Hofmeister series for both cations and anions, whereas molar water volume concurred with the cation series only. The results are discussed within the framework of a desolvation energy model that attributes solute-specific changes in equilibria to solute-dependent changes in the free energy of bulk water. PMID:22029390

Payumo, Alexander Y.; Huijon, R. Michael; Mansfield, Deauna D.; Belk, Laurel M.; Bui, Annie K.; Knight, Anne E.; Eggers, Daryl K.

2011-01-01

41

The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses and Aluminate Solutions - 13099  

SciTech Connect

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 NaOHNaAl(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 determined 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. (authors)

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)] [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)

2013-07-01

42

The component slope linear model for calculating intensive partial molar properties /application to waste glasses and aluminate solutions  

SciTech Connect

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 determined 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.

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, Richland, WA (United States)

2013-01-11

43

Partial molar volumes of oxide components in silicate liquids  

Microsoft Academic Search

Densities of 21 silicate liquids have been determined from 1,000 ° to 1,600 ° C. The compositions studied contain from two to eight oxide components and have the following ranges in composition (mole %): SiO2, 35–79%; TiO2, 4–36%; Al2O3, 5–25%; FeO, 11–41%; MgO, 7–28%; CaO, 7–35%; Na2O, 5–50%; and K2O, 4–20%. The compositions thus cover the upper range observed in

S. A. Nelson; I. S. E. Carmichael

1979-01-01

44

Raman studies of hydration of hydroxy complexes and the effect on standard partial molar heat capacities  

NASA Astrophysics Data System (ADS)

Raman spectroscopic studies of aqueous hydroxy complexes B(OH) 3, B(OH) 42-, Al(OH) 4-, Zn(OH) 42-, and their deuterated analogues provide compelling evidence for the presence of strong hydrogen bonding of water in the outer solvation sphere to the oxygen of the hydroxy ligand in the first coordination sphere. The deuterated complexes are more strongly hydrogen bonded than the hydrogen complexes. The fact that these hydrogen-bonding effects for the hydroxy borates are much more pronounced than for the aluminate and zincate anions can account for the unexpectedly large differences in the standard partial molar heat capacities of B(OH) 4- and A1(OH) 4-. The extension of semi-empirical solvation models based on the Born approximation for aqueous hydrolyzed species will need to consider the rather large and specific effect of hydrogen bonding of water to the hydroxide ion.

Brooker, Murray H.; Tremaine, Peter R.

1992-06-01

45

Partial molar enthalpies and reaction enthalpies from equilibrium molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

We present a new molecular simulation technique for determining partial molar enthalpies in mixtures of gases and liquids from single simulations, without relying on particle insertions, deletions, or identity changes. The method can also be applied to systems with chemical reactions. We demonstrate our method for binary mixtures of Weeks-Chandler-Anderson particles by comparing with conventional simulation techniques, as well as for a simple model that mimics a chemical reaction. The method considers small subsystems inside a large reservoir (i.e., the simulation box), and uses the construction of Hill to compute properties in the thermodynamic limit from small-scale fluctuations. Results obtained with the new method are in excellent agreement with those from previous methods. Especially for modeling chemical reactions, our method can be a valuable tool for determining reaction enthalpies directly from a single MD simulation.

Schnell, Sondre K.; Skorpa, Ragnhild; Bedeaux, Dick; Kjelstrup, Signe; Vlugt, Thijs J. H.; Simon, Jean-Marc

2014-10-01

46

Partial molar enthalpies and reaction enthalpies from equilibrium molecular dynamics simulation.  

PubMed

We present a new molecular simulation technique for determining partial molar enthalpies in mixtures of gases and liquids from single simulations, without relying on particle insertions, deletions, or identity changes. The method can also be applied to systems with chemical reactions. We demonstrate our method for binary mixtures of Weeks-Chandler-Anderson particles by comparing with conventional simulation techniques, as well as for a simple model that mimics a chemical reaction. The method considers small subsystems inside a large reservoir (i.e., the simulation box), and uses the construction of Hill to compute properties in the thermodynamic limit from small-scale fluctuations. Results obtained with the new method are in excellent agreement with those from previous methods. Especially for modeling chemical reactions, our method can be a valuable tool for determining reaction enthalpies directly from a single MD simulation. PMID:25318729

Schnell, Sondre K; Skorpa, Ragnhild; Bedeaux, Dick; Kjelstrup, Signe; Vlugt, Thijs J H; Simon, Jean-Marc

2014-10-14

47

Strongly Composition-Dependent Partial Molar Compressibility of Water in Silicate Glasses  

NASA Astrophysics Data System (ADS)

Water and other volatiles have long been known to play a fundamental role in igneous processes, yet their influence on the physical properties of melts are still not well enough understood. Of particular interest is the density contrast between liquid and solid phases, which facilitates melt extraction and migration. Owing to its low molecular weight, dissolved water must decrease magma density, but the way it does so as a function of pressure remains largely to be determined. Studies on quenched melts (glasses) provide useful information because the glass has the same structure as the melt. We measured compressional and shear wave velocities of seven series of hydrous aluminosilicate glasses by Brillouin scattering at room temperature and pressure. The glasses were quenched from high temperature and 2 or 3 kbar pressure. The dry end-members range from highly polymerized albitic and granitic compositions, to depolymerized synthetic analogues of mantle-derived melts. For each set of glasses, the adiabatic shear and bulk moduli have been calculated from the measured sound velocities and densities. These moduli are linear functions of water content up to 5 wt % H2O, the highest concentration investigated, indicating that both are independent of water speciation in all series. For water-free glasses, the bulk modulus decreases from about 65 to 35 GPa with increasing degree of polymerization. Sympathetically, the partial molar bulk modulus of the water component decreases from 114 to 8 GPa, such that dissolved water amplifies the differences in rigidity between the anhydrous glasses. This strong variation indicates that the solubility mechanisms of water depend strongly on silicate composition. Depolymerized liquids are also much less compressible than their polymerized counterparts, suggesting that the partial molar compressibility of dissolved water approaches zero in depolymerized liquids. If this is correct, hydrous mantle melts formed beneath volcanic arcs would be more buoyant at depth than previously thought, facilitating their extraction and rapid ascent.

Whittington, A. G.; Richet, P.; Polian, A.

2010-12-01

48

Temperature Dependence of Excess Molar Volumes of Ethanol + Water + Ethyl Acetate  

Microsoft Academic Search

In order to design and optimize equipment needed for production of distilled alcoholic beverages, an adequate knowledge of their physical properties and phase equilibria is necessary. The key thermodynamic information needed is for those chemicals that are the main components in terms of nonideal behavior. In this paper we present the temperature dependence of the excess molar volumes of the

J. M. Resa; C. González; J. M. Goenaga; M. Iglesias

2004-01-01

49

Determination of the Molar Volume of Hydrogen from the Metal-Acid Reaction: An Experimental Alternative.  

ERIC Educational Resources Information Center

Describes an alternative technique for determining the molar volume of hydrogen from the metal-acid reaction in which the metal sample is encased in a specially prepared cage and a pipette filler is used to fill an inverted burette with water. Eliminates some difficulties encountered with the conventional technique. (JRH)

de Berg, Kevin; Chapman, Ken

1996-01-01

50

Hydration effects on molar volume and compressibility of olivine  

NASA Astrophysics Data System (ADS)

Hydrous olivines have been synthesized at 12 GPa at various conditions of temperature, silica activity, and fayalite content. Samples were characterized by FTIR and Raman spectroscopy and single crystal X-ray diffraction. We observe a maximum water content of 8800 parts per million by weight H2O at 1250°C in both Fo90 and Fo100 compositions, with lower H2O contents at 1100°C and 1400°C. We observe similar amounts of hydration and FTIR spectra in samples coexisting with clinoenstatite and with clinohumite. We observe a systematic expansion of the unit cell volume with hydration so that an addition of 5000 ppmw H2O has the same effect on density as raising the temperature by 240°C. Compression experiments have been carried out in the diamond anvil cell to 8 GPa. We observe a decrease in the isothermal bulk modulus from about 128 GPa to about 120 GPa at 8000 ppmw H2O, which is similar in magnitude to the elastic softening of wadsleyite and ringwoodite with hydration. FTIR spectra and X-ray structure refinements indicate that the principal hydration mechanism is substitution of 2H+ for Mg2+ so that the geochemical compatibility of H appears to dramatically increase with pressure in the upper mantle near the 410 km discontinuity.

Smyth, J. R.; Nestola, F.; Frost, D. J.; Holl, C. M.; Bromiley, G.

2005-12-01

51

Partial specific volume of amylose  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

52

Partial specific volume of Pullulan  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

53

Spectrum of excess partial molar absorptivity. I. Near infrared spectroscopic study of aqueous acetonitrile and acetone.  

PubMed

We study the mixing schemes or the molecular processes occurring in aqueous acetonitrile (ACN) and acetone (ACT) by near-infrared spectroscopy (NIR). Both solutions (any other aqueous solutions) are not free from strong and complex intermolecular interactions. To tackle such a many-body problem, we first use the concept of the excess molar absorptivity, epsilonE, which is a function of solute mole fraction in addition to that of wavenumber, nu. The plots of epsilonE calculated from NIR spectra for both aqueous solutions against nu showed two clearly separated bands at 5020 and 5230 cm(-1); the former showed negative and the latter positive peaks. At zero and unity mole fractions of solute, epsilonE is identically zero independent of nu. Similar to the thermodynamic excess functions, both negative and positive bands grow in size from zero to the minimum (or the maximum) and back to zero, as the mole fraction varies from 0 to 1. Since the negative band's nu-locus coincides with the NIR spectrum of ice, and the positive with that of liquid H(2)O, we suggest that on addition of solute the "ice-likeness" decreases and the "liquid-likeness" increases, reminiscent of the two-mixture model for liquid H(2)O. The modes of these variations, however, are qualitatively different between ACN-H(2)O and ACT-H(2)O. The former ACN is known to act as a hydrophobe and ACT as a hydrophile from our previous thermodynamic studies. To see the difference more clearly, we introduced and calculated the excess partial molar absorptivity of ACN and ACT, epsilon(E)(N) and epsilon(E)(T), respectively. The mole fraction dependences of epsilon(E)(N) and epsilon(E)(T) show qualitatively different behavior and are consistent with the detailed mixing schemes elucidated by our earlier differential thermodynamic studies. Furthermore, we found in the H(2)O-rich region that the effect of hydrophobic ACN is acted on the negative band at 5020 cm(-1), while that of hydrophilic ACT is on the positive high-energy band. Thus, the present method of analysis adds more detailed insight into the difference between a hydrophobe and a hydrophile in their effects on H(2)O. PMID:19678652

Koga, Yoshikata; Sebe, Fumie; Minami, Takamasa; Otake, Keiko; Saitow, Ken-ichi; Nishikawa, Keiko

2009-09-01

54

Partial volume correction in quantitative amyloid imaging.  

PubMed

Amyloid imaging is a valuable tool for research and diagnosis in dementing disorders. As positron emission tomography (PET) scanners have limited spatial resolution, measured signals are distorted by partial volume effects. Various techniques have been proposed for correcting partial volume effects, but there is no consensus as to whether these techniques are necessary in amyloid imaging, and, if so, how they should be implemented. We evaluated a two-component partial volume correction technique and a regional spread function technique using both simulated and human Pittsburgh compound B (PiB) PET imaging data. Both correction techniques compensated for partial volume effects and yielded improved detection of subtle changes in PiB retention. However, the regional spread function technique was more accurate in application to simulated data. Because PiB retention estimates depend on the correction technique, standardization is necessary to compare results across groups. Partial volume correction has sometimes been avoided because it increases the sensitivity to inaccuracy in image registration and segmentation. However, our results indicate that appropriate PVC may enhance our ability to detect changes in amyloid deposition. PMID:25485714

Su, Yi; Blazey, Tyler M; Snyder, Abraham Z; Raichle, Marcus E; Marcus, Daniel S; Ances, Beau M; Bateman, Randall J; Cairns, Nigel J; Aldea, Patricia; Cash, Lisa; Christensen, Jon J; Friedrichsen, Karl; Hornbeck, Russ C; Farrar, Angela M; Owen, Christopher J; Mayeux, Richard; Brickman, Adam M; Klunk, William; Price, Julie C; Thompson, Paul M; Ghetti, Bernadino; Saykin, Andrew J; Sperling, Reisa A; Johnson, Keith A; Schofield, Peter R; Buckles, Virginia; Morris, John C; Benzinger, Tammie L S

2015-02-15

55

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

Microsoft Academic Search

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) alpha and isothermal compressibility kappa were determined by fitting

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

2005-01-01

56

Molecular dynamics simulation of the molar volumes and solubility parameters of straight alkanes  

NASA Astrophysics Data System (ADS)

The straight chain n-alkanes used as core materials to fabricate nanoencapsulated and microencapsulated phase change of materials (PCM) have received much attention in recent years. The dissipative particle dynamics (DPD) simulation method has been emerged to investigate the encapsulated PCM from the perspective of mesoscopic. To obtain the Flory-Huggins and repulsion parameters, which is essential for the DPD study, the molar volume and solubility parameter of straight alkanes are investigated by using molecular dynamics (MD) simulation. The results showed that a linear relationship of molar volume (V) with carbon atom number (n) and simulation temperature (T) can be obtained as: V = -31.73 + 0.26T + 14.82n. A nonlinear relationship of solubility parameter (?) with carbon atom number and simulation temperature can be described as: ? = 18.45-3.66 ×10-2n + 1.07T - 1.20 ×10-5n2 - 9.60 ×10-2T2 - 2.49 ×10-3nT. The equations can be used as a reference for the further DPD simulation in n-alkanes based PCM system.

Liu, Xinjian; Rao, Zhonghao; Huo, Yutao

2014-12-01

57

Thermodynamics of aqueous aluminum: standard partial molar heat capacities of Al/sup 3 +/ from 10 to 55/sup 0/C  

SciTech Connect

The thermodynamic properties of aqueous aluminum species are required over wide ranges of temperature in order to model mineral dissolution and transport in steam injection and combustion processes for the in situ recovery of bitumen. The same data are needed to model aqueous solutions associated with the formation of hydrothermal ore deposits, geothermal power generation, the marine chemistry of deep hydrothermal vents, hydrometallurgy, and the corrosion behavior of aluminum alloys. Apparent molar heat capacities and volumes of Al(NO/sub 3/)/sub 3/ and AlCl/sub 3/ have been measured at 25/sup 0/C in dilute aqueous acid solutions to suppress hydrolysis. Heat capacity results for AlCl/sub 3/ span the range 10-55/sup 0/C. The measurements yield standard partial molar heat capacities, anti C/sub p//sup 0/, and volumes, anti V/sup 0/, for the Al/sup 3 +/ (aq) ion: anti V/sub 298//sup 0/ (Al/sup 3 +/, aq) = -45.3 cm/sup 3/ mol/sup -1/, anti C/sub pT//sup 0/(Al/sup 3 +/, aq) = 566.2 - 1.452% - 27338/(T - 190), where T is the absolute temperature (K). Their result for anti V/sub 298//sup 0/ is consistent with published semi-empirical correlations. The result for anti C/sub p298//sup 0/ is more negative than that predicted from the entropy correspondence principle by 135 J K/sup -1/ mol/sup -1/ and casts doubt upon the correspondence method as a predictive tool. The heat capacities approach born behavior at elevated temperatures and appear to be consistent with the Helgeson-Kirkham-Flowers model for extrapolations to higher temperatures.

Hovey, J.K.; Tremaine, P.R.

1986-03-01

58

Excess molar volumes of mixtures of hexane + natural oils from 298.15 to 313.15 K  

SciTech Connect

Excess molar volume data for mixtures containing hexane with three edible oils: olive, corn, and pip of grape have been determined from density measurements at various temperatures between 298.15 and 313.15 K using a vibrating tube densimeter. Results have been correlated by the Redlich-Kister equation. Systems showed negative deviations from ideality in the whole composition range.

Gonzalez, C.; Resa, J.M.; Ruiz, A.; Gutierrez, J.I. [Univ. del Pais Vasco, Vitoria (Spain). Dept. of Chemical Engineering] [Univ. del Pais Vasco, Vitoria (Spain). Dept. of Chemical Engineering

1997-03-01

59

Excess molar volumes and viscosities of binary mixtures of 2-butoxyethanol (butyl cellosolve) with chloroalkanes at 298.15 K  

Microsoft Academic Search

Molar excess volumes (VE) and dynamic viscosities (?) have been measured for non-electrolyte mixtures of 2-butoxyethanol (butyl cellosolve) with dichloromethane, trichloromethane or tetrachloromethane at 298.15 K over the whole concentration range. The excess volume curves are sigmoid with a maximum in the chloroalkane-rich region. From the experimental data excess viscosities (?Eln?) and excess energies of activation for viscous flow (?G?E)

Amalendu Pal; Wazir Singh

1997-01-01

60

Molar Uprighting  

MedlinePLUS

Molar Uprighting What Is It? What It's Used For Preparation How It's Done Follow-Up Risks When ... Call a Professional Additional Info What Is It? Molar uprighting corrects a tilted molar. Molars are the ...

61

Correction for Partial Volume Effects in PET: Principle and Validation  

Microsoft Academic Search

The accuracy of PET for measuring regional radiotracer concentra tions in the human brain is limited by the finite resolution capability of the scanner and the resulting partial volume effects (PVEs). We designed a new algorithm to correct for PVEs by characterizing the geometric interaction between the PETsystem and the brain activity distribution. Methods: The partial volume correction (PVC) algo

O. G. Rousset; Yilong Ma; Alan C. Evans

1998-01-01

62

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

SciTech Connect

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.

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

63

Apparent molar volumes of La(CF{sub 3}SO{sub 3}){sub 3}(aq) and Gd(CF{sub 3}SO{sub 3}){sub 3}(aq) at 278 K, 298 K, and 318 K at pressures to 30.0 MPa  

SciTech Connect

Densities of La(CF{sub 3}SO{sub 3}){sub 3}(aq) and Gd(CF{sub 3}SO{sub 3}){sub 3}(aq) have been measured at 278 K, 298 K, and 318 K at pressures of 0.1 MPa, 7.0 MPa, and 30.0 MPa using vibrating-tube densimeters. Apparent molar volumes obtained from the density data have been fitted to the Pitzer equation. The standard partial molar volumes V{sub {phi}}{sup {infinity}} and the ion-interaction parameters {beta}{sup (0)V} and {beta}{sup (1)V} have been determined through least-squares fitting to the experimental results. The standard partial molar volume of the trifluoromethanesulfonate anion V{sub {phi}}{sup {infinity}}(CF{sub 3}SO{sub 3}{sup {minus}},aq) was calculated at 298 K and 0.1 MPa from the partial molar volumes of the gadolinium and lanthanum salts and the available values for the standard partial molar volumes of the cations. Excellent agreement is obtained for V{sub {phi}}{sup {infinity}}(CF{sub 3}SO{sub 3}{sup {minus}},aq) calculated from the data for the two salts.

Xiao, C.; Tremaine, P.R. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Dept. of Chemistry] [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Dept. of Chemistry; Simonson, J.M. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.] [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

1996-09-01

64

Partial specific volume of amylose acetate  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

65

Partial specific volume of poly(isobutylene)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

66

Partial volume correction strategies for quantitative FDG PET in oncology  

Microsoft Academic Search

Purpose  Quantitative accuracy of positron emission tomography (PET) is affected by partial volume effects resulting in increased underestimation\\u000a of the standardized uptake value (SUV) with decreasing tumour volume. The purpose of the present study was to assess accuracy\\u000a and precision of different partial volume correction (PVC) methods.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Three methods for PVC were evaluated: (1) inclusion of the point spread function (PSF)

Nikie J. Hoetjes; Floris H. P. van Velden; Otto S. Hoekstra; Corneline J. Hoekstra; Nanda C. Krak; Adriaan A. Lammertsma; Ronald Boellaard

2010-01-01

67

Partial volume correction of magnetic resonance spectroscopic imaging  

NASA Astrophysics Data System (ADS)

The ability to study the biochemical composition of the brain is becoming important to better understand neurodegenerative and neurodevelopmental disorders. Magnetic Resonance Spectroscopy (MRS) can non-invasively provide quantification of brain metabolites in localized regions. The reliability of MRS is limited in part due to partial volume artifacts. This results from the relatively large voxels that are required to acquire sufficient signal-to-noise ratios for the studies. Partial volume artifacts result when a MRS voxel contains a mixture of tissue types. Concentrations of metabolites vary from tissue to tissue. When a voxel contains a heterogeneous tissue composition, the spectroscopic signal acquired from this voxel will consist of the signal from different tissues making reliable measurements difficult. We have developed a novel tool for the estimation of partial volume tissue composition within MRS voxels thus allowing for the correction of partial volume artifacts. In addition, the tool can localize MR spectra to anatomical regions of interest. The tool uses tissue classification information acquired as part of a structural MR scan for the same subject. The tissue classification information is co-registered with the spectroscopic data. The user can quantify the partial volume composition of each voxel and use this information as covariates for metabolite concentrations.

Lu, Yao; Wu, Dee; Magnotta, Vincent A.

2007-03-01

68

Fragility and molar volumes of non-stoichiometric chalcogenides: The crucial role of melt/glass homogenization  

NASA Astrophysics Data System (ADS)

Melt-fragility index (m) and glass molar volumes (Vm) of binary Ge-Se melts/glasses are found to change reproducibly as they are homogenized. Variance of Vm decreases as glasses homogenize, and the mean value of Vm increases to saturate at values characteristic of homogeneous glasses. Variance in fragility index of melts also decreases as they are homogenized, and the mean value of m decreases to acquire values characteristic of homogeneous melts. Broad consequences of these observations on physical behavior of chalcogenides melts/glasses are commented upon. The intrinsically slow kinetics of melt homogenization derives from high viscosity of select super-strong melt compositions in the Intermediate Phase that serve to bottleneck atomic diffusion at high temperatures.

Bhageria, R.; Gunasekera, K.; Boolchand, P.; Micoulaut, M.

2014-07-01

69

Hygrometer for Detecting Water in Partially Enclosed Volumes  

NASA Technical Reports Server (NTRS)

A portable hygrometer has been devised to implement a pre-existing technique for detecting water trapped in partially enclosed volumes that may be difficult to reach and cannot be examined directly. The technique is based on the fact that eventually the air in such a volume becomes saturated or nearly so. The technique is straightforward: One measures the relative humidity and temperature of both the ambient air and a sample of air from the enclosed volume. If the relative humidity of the sample is significantly greater than that of the ambient air and/or if the sample is at or close to the dew point, then it can be concluded that water is trapped in the volume. Of course, the success of this technique depends on the existence of an access hole through which one can withdraw some air from the enclosed volume.

Youngquist, Robert C.; Surma, Jan; Parks, Steve

2005-01-01

70

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

USGS Publications Warehouse

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.

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

2005-01-01

71

Denoising arterial spin labeling MRI using tissue partial volume  

NASA Astrophysics Data System (ADS)

Arterial spin labeling (ASL) is a noninvasive MRI method that uses magnetically labeled blood to measure cerebral perfusion. Spatial resolution of ASL is relatively small and as a consequence perfusion from different tissue types is mixed in each pixel. An average ratio of gray matter (GM) to white matter (WM) blood flow is 3.2 to 1. Disregarding the partial volume effects (PVE) can thus cause serious errors of perfusion quantification. PVE also complicates spatial filtering of ASL images as apart from noise there is a spatial signal variation due to tissue partial volume. Recently, an algorithm for correcting PVE has been published by Asllani et al. It represents the measured magnetization as a sum of different tissue magnetizations weighted by their fractional volume in a pixel. With the knowledge of the partial volume obtained from a high-resolution MRI image, it is possible to separate the individual tissue contributions by linear regression on a neighborhood of each pixel. We propose an extension of this algorithm by minimizing the total-variation of the tissue specific magnetization. This makes the algorithm more flexible to local changes in perfusion. We show that this method can be used to denoise ASL images without mixing the WM and GM signal.

Petr, Jan; Ferre, Jean-Christophe; Gauvrit, Jean-Yves; Barillot, Christian

2010-03-01

72

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

Microsoft Academic Search

Molar heat capacities at constant volume (Cv) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by

T. O. Lueddecke; J. W. Magee

1996-01-01

73

PROPERTIES OF THE SYSTEM URANYL NITRATE-ALUMINUM NITRATE-NITRIC ACID (OR SODIUM HYDROXIDE)SODIUM NITRATE-WATER-HEXONE. PART 2. DENSITY, APPARENT MOLAR VOLUME AND VISCOSITY  

Microsoft Academic Search

The viscosity and density of various Redox Process solutions were ; determined at 15, 25. and 40 ction prod- C. Apparent molar volumes for UO\\/sub ; 2\\/(NOâ)â and HNOâ in hexone and in aqueou s solutions were ; calculated from the density data as a function of concentration. The molar ; volumes of Al(NOâ)â in water and of hexone in

L. L. Burger; I. M. Rehn; H. R. Schmidt; C. M. Slansky

1949-01-01

74

CORTICAL BRAIN SURFACE MAPPING FOR STUDYING PARTIAL VOLUME EFFECTS IN BRAIN FDG PET IMAGES  

E-print Network

CORTICAL BRAIN SURFACE MAPPING FOR STUDYING PARTIAL VOLUME EFFECTS IN BRAIN FDG PET IMAGES Hillary PET images is confounded by tissue atrophy and partial volume effects, especially in patients-based cortical brain surface mapping technique to account for partial volume effects on brain FDG PET images

Thompson, Paul

75

The Molar Volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 Spinels  

NASA Astrophysics Data System (ADS)

A new model of molar volume has been calibrated in the spinel supersystem (Mg,Fe2+)(Al,Cr,Fe3+)2O4 - (Mg,Fe2+)2TiO4. A total of 832 X-ray and neutron diffraction experiments performed on spinels at ambient and in situ high-P, T conditions (from the American Mineralogist Crystal Structure Database (Downs and Hall-Wallace, 2003) and other sources) were used to calibrate end-member equations of state and an excess volume model for this system. The effect on molar volume of cation ordering over the octahedral and tetrahedral sites is captured with linear dependence on Mg2+, Al3+, and Fe3+ site occupancy terms. We allowed standard state volumes and coefficients of thermal expansion of the end members to vary within their uncertainties during extraction of the mixing properties, in order to achieve the best fit. Published equations of states of the various spinel end members were analyzed to obtain optimal values of the bulk modulus and its pressure derivative, for each explicit end member. For any spinel composition in the supersystem, the model molar volume is obtained by adding excess volume and cation order-dependent terms to a linear combination of the five end member volumes, estimated at pressure and temperature using the high-T Vinet equation of state. The model has a total of 31 parameters and fits nearly all experiments to within 0.02 J/bar/mol, or better than 0.5% in volume. The model is compared to the current MELTS (Ghiorso and Sack, 1995; Ghiorso et al., 2002) spinel model with a demonstration of the impact of the model difference on the estimated spinel-garnet lherzolite transition pressure. Our primary motivation in this work is the development of a comprehensive spinel molar volume model for use in calibration of activity-composition models of garnet and pyroxene solid solutions. The thermodynamic models, along with a new silicate liquid equation of state, will be incorporated into the next generation MELTS model, xMELTS. The new solid solution models will include some minor components, including Ti4+ and Cr3+. Because most constraints on the activity of garnet and pyroxene at high-P are derived from experiments with coexisting spinel, we must be confident in the ability of our spinel model to realistically reproduce thermodynamic behavior over all applicable compositions. Additionally, producing a spinel molar volume model calibrated with recent in situ high-P, T diffraction data is crucial to our ability to accurately model the spinel-garnet transition in Earth's upper mantle. For example, we recently calibrated Cr-Al exchange equilibria for garnet and spinel. When this new calibration is used with the current MELTS model, a region of garnet-spinel coexistence in lherzolites is predicted with width in pressure comparable to experimental constraints. The transition occurs, however, at the unexpectedly low pressure of ~1.7 GPa. The improved model of spinel molar volume presented here, along with a new garnet molar volume model in the system FeO-MgO-CaO-Fe2O3-Cr2O3-Al2O3-TiO2-Na2O-SiO2 currently being calibrated, will enable coupled recalibration of the garnet and pyroxene models to match both the absolute pressure and width of this key transition in mantle lithology.

Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

2011-12-01

76

Segmentation-based partial volume correction for volume estimation of solid lesions in CT.  

PubMed

In oncological chemotherapy monitoring, the change of a tumor's size is an important criterion for assessing cancer therapeutics. Measuring the volume of a tumor requires its delineation in 3-D. This is called segmentation, which is an intensively studied problem in medical image processing. However, simply counting the voxels within a binary segmentation result can lead to significant differences in the volume, if the lesion has been segmented slightly differently by various segmentation procedures or in different scans, for example due to the limited spatial resolution of computed tomography (CT) or partial volume effects. This variability limits the sensitivity of size measurements and thus of therapy response assessments and it can even lead to misclassifications. We present a fast, generic algorithm for measuring the volume of solid, compact tumors in CT that considers partial volume effects at the border of a given segmentation result. The algorithm is an extension of the segmentation-based partial volume analysis proposed by Kuhnigk for the volumetry of solid lung lesions , such that it can be applied to inhomogeneous lesions and lesions with inhomogeneous surroundings. Our generalized segmentation-based partial volume correction is based on a spatial subdivision of the segmentation result, from which the fraction of tumor for each voxel is computed. It has been evaluated on phantom data, 1516 lesion segmentation pairs (lung nodules, liver metastases and lymph nodes) as well as 1851 lung nodules from the LIDC-IDRI database. The evaluations of our algorithm show a more accurate estimation of the real volume and its ability to reduce inter- and intra-observer variability significantly for each entity. Overall, the variability (interquartile range) for phantom data is reduced by 49% ( p ? 0.001) and the variability between different readers is reduced by 28% ( p ? 0.001). The average computation time is 0.2 s. PMID:24184707

Heckel, Frank; Meine, Hans; Moltz, Jan H; Kuhnigk, Jan-Martin; Heverhagen, Johannes T; Kiessling, Andreas; Buerke, Boris; Hahn, Horst K

2014-02-01

77

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

SciTech Connect

Molar heat capacities at constant volume (C{sub v}) of difluoromethane (R32) and pentafluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase (C{sub v}{sup (2)}), saturated liquid (C{sub {sigma}} or C {prime}{sub x}), and single-phase (C{sub v}) molar heat capacities. The C{sub {sigma}} data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature (T{sub tr}) and the enthalpy of fusion ({Delta}{sub fus}H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded uncertainty (at the two-sigma level) for C{sub v} is estimated to be 0.7%, for C{sub v}{sup (2)} it is 0.5%, and for C{sub {sigma}} it is 0.7%.

Lueddecke, T.O.; Magee, J.W. [National Inst. of Standards and Technology, Boulder, CO (United States)

1996-07-01

78

Excess molar volumes of 2-(2-alkoxyethoxy)ethanols with trichloroethylene and tetrachloroethylene at 298.15 and 308.15 K  

Microsoft Academic Search

The excess molar volumes for binary liquid mixtures of trichloroethylene, CâClâH and tetrachloroethylene, CâClâ, with 2-(2-methoxyethoxy)ethanol, CHâO(CHâ)âO(CHâ)âOH, 2-(2-ethoxyethoxy)ethanol, CâHâO(CHâ)âO(CHâ)âOH, and 2-(2-butoxyethoxy)ethanol, CâHâO(CHâ)âO(CHâ)âOH, have been measured using a continuous-dilution dilatometer over the entire mole fraction range at 298.15 and 308.15 K. The excess volumes change sign for trichloroethylene and are positive for tetrachloroethylene with 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, and 2-(2-butoxyethoxy)ethanol over the whole

Amalendu Pal; Wazir Singh

1995-01-01

79

Post-Reconstruction Partial Volume Correction of PET Images Using Iterative Deconvolution Algorithm and Anatomical Priors  

Microsoft Academic Search

\\u000a PET image quality is affected by partial volume effect (PVE). Moreover, PVE can lead to inaccurate estimate of radiotracer\\u000a concentration in each voxel of the reconstructed PET volume. Several methods could be used to correct PET images for PVE and\\u000a can be mainly grouped into two categories: pre- and post-reconstruction approaches. The paper presents a novel post-reconstruction\\u000a partial volume correction

D. D’Ambrosio; M. Marengo; S. Boschi; S. Fanti; A. E. Spinelli

80

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

NASA Astrophysics Data System (ADS)

Molar heat capacities at constant volume ( C v) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase ( C {v/(2)}), saturated liquid ( C ? or C' x ), and singlephase ( C v) molar heat capacities. The C ? data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature ( T tr) and the enthalpy of fusion (?fus H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-ofvolume work adjustment. The expanded uncertainty (at the two-sigma level) for C v is estimated to be 0.7%, for C {v/(2)} it is 0.5%, and for C ? it is 0.7%.

Lüddecke, T. O.; Magee, J. W.

1996-07-01

81

Apparent molar volumes and apparent molar heat capacities of Pr(NO3)3(aq), Gd(NO3)3(aq), Ho(NO3)3(aq), and Y(NO3)3(aq) at T = (288.15, 298.15, 313.15 and 328.15) K and p = 0.1 MPa  

SciTech Connect

Relative densities and relative massic heat capacities have been measured for acidified solutions (prepared at University of Lethbridge) of Y(NO{sub 3}){sub 3}(aq), Pr(NO{sub 3}){sub 3}(aq), and Gd(NO{sub 3}){sub 3}(aq) at T = (288.15, 298.15, 313.15, and 328.15) K and p = 0.1 MPa. In addition, relative densities and massic heat capacities have been measured at the same temperatures and pressure for Y(NO{sub 3}){sub 3}(aq) and Ho(NO{sub 3}){sub 3}(aq) solutions which were supplied from the Lawrence Livermore National Laboratory (LLNL) (n.b. measurements at T = 328.15 K for Ho(NO{sub 3}){sub 3}(aq) were not performed due to the limited volume of solution available). Apparent molar volumes and apparent molar heat capacities for the aqueous salt solutions have been calculated from the experimental apparent molar properties of the acidified salt solutions using Young's Rule whereas the apparent molar properties of the LLNL solutions were calculated directly from the measured densities and massic heat capacities. The two sets of data for the Y(NO{sub 3}){sub 3}(aq) systems provide a check of the internal consistency of the Young's Rule approach we have utilized. The concentration dependences of the apparent molar volumes and heat capacities of the aqueous salt solutions have been modeled at each investigated temperature using the Pitzer ion interaction equations to yield apparent molar properties at infinite dilution. Complex formation within the aqueous rare earth nitrate systems is discussed and is qualitatively explored by probing the concentration dependence of apparent molar volumes and heat capacities. It is also shown that in spite of the complex formation within the aqueous rare earth nitrate systems there remains a high degree of self-consistency between the apparent molar volumes and heat capacities at infinite dilution reported in this manuscript and those previously reported for aqueous rare earth perchlorate salt systems.

Rard, J; Lui, J; Erickson, K; Munoz, J; Hakin, A H

2004-07-13

82

Molar volume of superfluid 3He-4He mixtures:?The dependence of the Bardeen-Baym-Pines parameter on temperature, pressure, and 3He concentration  

NASA Astrophysics Data System (ADS)

We have developed a new method for determining the Bardeen-Baym-Pines (BBP) parameter of a superfluid 3He-4He mixture from the measurement of its molar volume within the wide ranges of temperature, pressure, and the 3He concentration. The method and the results are described. The ranges of the present investigation are 0.4 660 mK in temperature, 0.3 10 kgf/cm2 in pressure, and 0.07 0.39 in the 3He concentration. The data obtained are fitted with a formula based on the phenomenological theory of dilute solutions of 3He in superfluid 4He. Our empirical formula can reproduce the experimental values of the BBP parameter within the accuracy of 1%. The argument on the absolute uncertainty is also given.

Hatakeyama, Ken; Noma, Satoshi; Tanaka, Etsutaro; Burmistrov, Serguei N.; Satoh, Takeo

2003-03-01

83

Partial volume effect modeling for segmentation and tissue classification of brain magnetic resonance images: A review  

PubMed Central

Quantitative analysis of magnetic resonance (MR) brain images are facilitated by the development of automated segmentation algorithms. A single image voxel may contain of several types of tissues due to the finite spatial resolution of the imaging device. This phenomenon, termed partial volume effect (PVE), complicates the segmentation process, and, due to the complexity of human brain anatomy, the PVE is an important factor for accurate brain structure quantification. Partial volume estimation refers to a generalized segmentation task where the amount of each tissue type within each voxel is solved. This review aims to provide a systematic, tutorial-like overview and categorization of methods for partial volume estimation in brain MRI. The review concentrates on the statistically based approaches for partial volume estimation and also explains differences to other, similar image segmentation approaches. PMID:25431640

Tohka, Jussi

2014-01-01

84

Partial volume effect modeling for segmentation and tissue classification of brain magnetic resonance images: A review.  

PubMed

Quantitative analysis of magnetic resonance (MR) brain images are facilitated by the development of automated segmentation algorithms. A single image voxel may contain of several types of tissues due to the finite spatial resolution of the imaging device. This phenomenon, termed partial volume effect (PVE), complicates the segmentation process, and, due to the complexity of human brain anatomy, the PVE is an important factor for accurate brain structure quantification. Partial volume estimation refers to a generalized segmentation task where the amount of each tissue type within each voxel is solved. This review aims to provide a systematic, tutorial-like overview and categorization of methods for partial volume estimation in brain MRI. The review concentrates on the statistically based approaches for partial volume estimation and also explains differences to other, similar image segmentation approaches. PMID:25431640

Tohka, Jussi

2014-11-28

85

A Unifying Framework for Inhomogeneity Correction and Partial Volume Segmentation of Brain MR Images  

E-print Network

and partial volume (PV) segmentation of multi-spectral brain magnetic resonance (MR) images. The MR data by the National Institutes of Health (grant #CA82402), the National Multiple Sclerosis Society (grant #RG3042-A-2

86

Molar and excess volumes of liquid In-Sb, Mg-Sb, and Pb-Sb alloys  

SciTech Connect

By a direct Archimedes' technique, volumetric data were obtained for liquid In, Mg, Pb, and Sb and mixtures of In-Sb, Mg-Sb, and Pb-Sb. In this paper the excess volumes for the alloys studied are presented and discussed.

Hansen, A.R.; Kaminski, M.A. (Dept. of Chemical Engineering, Univ. of Illinois, Urbana, IL (US)); Eckert, C.A. (School of Chemical Engineering, Georgia Inst. of Technology, Atlanta, GA (US))

1990-04-01

87

FMDP Reactor Alternative Summary Report: Volume 3 - partially complete LWR alternative  

SciTech Connect

The Department of Energy Office of Fissile Materials Disposition (DOE/MD) initiated a detailed analysis activity to evaluate each of ten plutonium disposition alternatives that survived an initial screening process. This document, Volume 3 of a four volume report summarizes the results of these analyses for the partially complete LWR (PCLWR) reactor based plutonium disposition alternative.

Greene, S.R.; Fisher, S.E.; Bevard, B.B. [and others

1996-09-01

88

The effect of perfluorocarbon vapour on the measurement of respiratory tidal volume during partial liquid ventilation.  

PubMed

During partial liquid ventilation perfluorocarbon vapour is present in the exhaled gases. The volumes of these gases are measured by pneumotachometers. Error in measuring tidal volumes will give erroneous measurement of lung compliance during partial liquid ventilation. We aim to compare measured tidal volumes with and without perfluorocarbon vapour using tidal volumes suitable for use in neonates. Tidal volumes were produced with a 100 ml calibration syringe from 20 to 100 ml and with a calibrated Harvard rodent ventilator from 2.5 to 20 ml. Control tidal volumes were drawn from a humidifier chamber containing water vapour and the PFC tidal volumes were drawn from a humidifier chamber containing water and perfluorocarbon (FC-77) vapour. Tidal volumes were measured by a fixed orifice, target, differential pressure flowmeter (VenTrak) or a hot-wire anenometer (Bear Cub) placed between the calibration syringe or ventilator and the humidifier chamber. All tidal volumes measured with perfluorocarbon vapour were increased compared with control (ANOVA p < 0.001 and post t-test p < 0.0001). Measured tidal volume increased from 7 to 16% with the fixed orifice type flow-meter, and from 35 to 41% with the hot-wire type. In conclusion, perfluorocarbon vapour flowing through pneumotachometers gives falsely high tidal volume measurements. Calculation of lung compliance must take into account the effect of perfluorocarbon vapour on the measurement of tidal volume. PMID:10984211

Davies, M W; Dunster, K R

2000-08-01

89

Partial volume correction for volume estimation of liver metastases and lymph nodes in CT scans using spatial subdivision  

NASA Astrophysics Data System (ADS)

In oncological therapy monitoring, the estimation of tumor growth from consecutive CT scans is an important aspect in deciding whether the given treatment is adequate for the patient. This can be done by measuring and comparing the volume of a lesion in the scans based on a segmentation. However, simply counting the voxels within the segmentation mask can lead to significant differences in the volume, if the lesion has been segmented slightly differently by various readers or in different scans, due to the limited spatial resolution of CT and due to partial volume effects. We present a novel algorithm for measuring the volume of liver metastases and lymph nodes which considers partial volume effects at the surface of a lesion. Our algorithm is based on a spatial subdivision of the segmentation. We have evaluated the algorithm on a phantom and a multi-reader study. Our evaluations have shown that our algorithm allows determining the volume more accurately even for larger slice thicknesses. Moreover, it reduces inter-observer variability of volume measurements significantly. The calculation of the volume takes 2 seconds for 503 voxels on a single 2.66GHz Intel Core2 CPU.

Heckel, Frank; Dicken, Volker; Bostel, Tilman; Fabel, Michael; Kiessling, Andreas; Peitgen, Heinz-Otto

2010-03-01

90

Hybrid finite-volume\\/transported PDF simulations of a partially premixed methane–air flame  

Microsoft Academic Search

A hybrid finite-volume (FV)\\/transported probability density function (PDF) method is used for the simulation of a partially premixed flame with detailed chemistry. The FV code is implemented to handle detailed chemistry implicitly with no subgrid closure. A partially premixed methane–air flame is simulated to illustrate the need for closure. The PDF scheme is then substituted to handle the species transport using

Venkatramanan Raman; Rodney O. Fox; Albert D. Harvey

2004-01-01

91

Evaluation of the “effective volume shift” method for axial dispersion corrections in multi-detector size exclusion chromatography  

Microsoft Academic Search

Band broadening in size exclusion chromatography (SEC) causes errors in the calculated molar mass distribution even when molar-mass-sensitive detectors are used. These errors can be partially corrected by shifting the elution volume of the molar-mass-sensitive detector chromatogram relative to the concentration detector chromatogram, and then re-calculating the molar mass distribution. In this paper a computer simulation of multi-detector SEC of

Christian Jackson

1999-01-01

92

Chemistry and Physics of Lipids 143 (2006) 110 Partial molecular volumes of lipids and cholesterol  

E-print Network

Chemistry and Physics of Lipids 143 (2006) 1­10 Partial molecular volumes of lipids and cholesterol Available online 28 April 2006 Abstract Volumetric measurements are reported for fully hydrated lipid/cholesterol for mole fractions of cholesterol x from 0 to 0.5. Unlike previous cholesterol mixture studies, we

Nagle, John F.

93

JOURNAL OF PETROLOGY VOLUME 40 NUMBER 5 PAGES 831851 1999 Calculation of Peridotite Partial Melting from  

E-print Network

JOURNAL OF PETROLOGY VOLUME 40 NUMBER 5 PAGES 831­851 1999 Calculation of Peridotite Partial. Productivities forof the melting reaction for peridotite (S/F )rxn P , where F is the systems enriched peridotite residua decreasesreaction stoichiometry cause discontinuous changes in (S/F )rxn P . calculated

Asimow, Paul D.

94

JOURNAL OF PETROLOGY VOLUME 39 NUMBER 6 PAGES 10911115 1998 Calculation of Peridotite Partial Melting from  

E-print Network

JOURNAL OF PETROLOGY VOLUME 39 NUMBER 6 PAGES 1091­1115 1998 Calculation of Peridotite Partial of peridotite using of the results of calculations of peridotite melting using MELTS, there are a number the suitability of this peridotite have more MgO and less SiO2 than equivalent ex- perimentally derived liquids

Asimow, Paul D.

95

An MR image-guided, voxel-based partial volume correction method for PET images  

PubMed Central

Purpose: Partial volume effect in positron emission tomography (PET) can cause incorrect quantification of radiopharmaceutical uptake in functional imaging. A PET partial volume correction method is presented to attenuate partial volume blurring and to yield voxel-based corrected PET images. Methods: By modeling partial volume effect as a convolution of point spread function of the PET scanner, the reconstructed PET images are corrected by iterative deconvolution with an edge-preserving smoothness constraint. The constraint is constructed to restore discontinuities extracted from coregistered MR images but maintains the smoothness in radioactivity distribution. The correction is implemented in a Bayesian deconvolution framework and is solved by a conjugate gradient method. The performance of the method was compared with the geometric transfer matrix (GTM) method on a simulated dataset. The method was evaluated on synthesized brain FDG–PET data and phantom MRI–PET experiments. Results: The true PET activity of objects with a size of greater than the full-width at half maximum of the point spread function has been effectively restored in the simulated data. The partial volume correction method is quantitatively comparable to the GTM method. For synthesized FDG–PET with true activity 0 ?ci/cc for cerebrospinal fluid (CSF), 228 ?ci/cc for white matter (WM), and 621 ?ci/cc for gray matter (GM), the method has improved the radioactivity quantification from 186?±?16 ?ci/cc to 30?±?7 ?ci/cc in CSF, 317?±?15 ?ci/cc to 236?±?10 ?ci/cc for WM, 438?±?4 ?ci/cc to 592?±?5 ?ci/cc for GM. Both visual and quantitative assessments show improvement of partial volume correction in the synthesized and phantom experiments. Conclusions: The partial volume correction method improves the quantification of PET images. The method is comparable to the GTM method but does not need MR image segmentation or prior tracer distribution information. The voxel-based method can be particularly useful for combined PET/MRI studies. PMID:22225287

Wang, Hesheng; Fei, Baowei

2012-01-01

96

Comparison of EM-based and level set partial volume segmentations of MR brain images  

NASA Astrophysics Data System (ADS)

EM and level set algorithms are competing methods for segmenting MRI brain images. This paper presents a fair comparison of the two techniques using the Montreal Neurological Institute's software phantom. There are many flavors of level set algorithms for segmentation into multiple regions (multi-phase algorithms, multi-layer algorithms). The specific algorithm evaluated by us is a variant of the multi-layer level set algorithm. It uses a single level set function for segmenting the image into multiple classes and can be run to completion without restarting. The EM-based algorithm is standard. Both algorithms have the capacity to model a variable number of partial volume classes as well as image inhomogeneity (bias field). Our evaluation consists of systematically changing the number of partial volume classes, additive image noise, and regularization parameters. The results suggest that the performances of both algorithms are comparable across noise, number of partial volume classes, and regularization. The segmentation errors of both algorithms are around 5 - 10% for cerebrospinal fluid, gray and white matter. The level set algorithm appears to have a slight advantage for gray matter segmentation. This may be beneficial in studying certain brain diseases (Multiple Sclerosis or Alzheimer's disease) where small changes in gray matter volume are significant.

Tagare, Hemant D.; Chen, Yunmei; Fulbright, Robert K.

2008-03-01

97

Investigation of partial volume correction methods for brain FDG PET studies  

SciTech Connect

The use of positron emission tomography (PET) in quantitative fluorodeoxyglucose (FDG) studies of aging and dementia has been limited by partial volume effects. A general method for correction of partial volume effects (PVE) in PET involves the following common procedures; segmentation of MRI brain images into gray matter (GM), white matter (WM), cerebral spinal fluid (CSF), and muscle (MS) components; MRI PET registration; and generation of simulated PET images. Afterward, two different approaches can be taken. The first approach derives first a pixel-by-pixel correction map as the ratio of the measured image to the simulated image [with realistic full-width at half-maximum (FWHM)]. The correction map was applied to the MRI segmentation image. Regions of interest (ROI`s) can then be applied to give results free of partial volume effects. The second approach uses the ROI values of the simulated ``pure`` image (with negligible FWHM) and those of the simulated and the measured PET images to correct for the PVE effect. By varying the ratio of radiotracer concentrations for different tissue components, the in-plane FWHM`s of a three-dimensional point spread function, and the ROI size, the authors evaluated the performance of these two approaches in terms of their accuracy and sensitivity to different simulation configurations. The results showed that both approaches are more robust than the approach developed by Muller-Gartner et al., and the second approach is more accurate and more robust than the first. In conclusion, the authors recommend that the second approach should be used on FDG PET images to correct for partial volume effects and to determine whether an apparent change in GM radiotracer concentration is truly due to metabolic changes.

Yang, J.; Huang, S.C.; Mega, M.; Toga, A.W.; Small, G.W.; Phelps, M.E. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States); Lin, K.P. [Chung Yuan Christian Univ., Chung-Li (China). Dept. of Electrical Engineering] [Chung Yuan Christian Univ., Chung-Li (China). Dept. of Electrical Engineering

1996-12-01

98

Interface profile studies in immiscible and partially miscible binary polymer blends from free volume measurement  

NASA Astrophysics Data System (ADS)

The diffused interface widths in an immiscible and a partially miscible polymer blend namely Polyvinyl chloride/Ethylene vinyl acetate (PVC/EVA) and Polystyrene/Polymethylmethacrylate (PS/PMMA) are experimentally measured and reported here. A new empirical relation found between hydrodynamic interaction parameter ? derived from free volume data and the Flory-Huggins interaction parameter ? is used to construct density profile across the interface to derive the interface width in above two binary blends.

Ramya, P.; Meghala, D.; Pasang, T.; Raj, J. M.; Ranganathaiah, C.; Williams, J. F.

2013-06-01

99

Density Contrast Sedimentation Velocity for the Determination of Protein Partial-Specific Volumes  

PubMed Central

The partial-specific volume of proteins is an important thermodynamic parameter required for the interpretation of data in several biophysical disciplines. Building on recent advances in the use of density variation sedimentation velocity analytical ultracentrifugation for the determination of macromolecular partial-specific volumes, we have explored a direct global modeling approach describing the sedimentation boundaries in different solvents with a joint differential sedimentation coefficient distribution. This takes full advantage of the influence of different macromolecular buoyancy on both the spread and the velocity of the sedimentation boundary. It should lend itself well to the study of interacting macromolecules and/or heterogeneous samples in microgram quantities. Model applications to three protein samples studied in either H2O, or isotopically enriched H218O mixtures, indicate that partial-specific volumes can be determined with a statistical precision of better than 0.5%, provided signal/noise ratios of 50–100 can be achieved in the measurement of the macromolecular sedimentation velocity profiles. The approach is implemented in the global modeling software SEDPHAT. PMID:22028836

Brown, Patrick H.; Balbo, Andrea; Zhao, Huaying; Ebel, Christine; Schuck, Peter

2011-01-01

100

Finite-volume and partial quenching effects in the magnetic polarizability of the neutron  

E-print Network

There has been much progress in the experimental measurement of the electric and magnetic polarizabilities of the nucleon. Similarly, lattice QCD simulations have recently produced dynamical QCD results for the magnetic polarizability of the neutron approaching the chiral regime. In order to compare the lattice simulations with experiment, calculation of partial quenching and finite-volume effects is required prior to an extrapolation in quark mass to the physical point. These dependencies are described using chiral effective field theory. Corrections to the partial quenching effects associated with the sea-quark-loop electric charges are estimated by modelling corrections to the pion cloud. These are compared to the uncorrected lattice results. In addition, the behaviour of the finite-volume corrections as a function of pion mass is explored. Box sizes of approximately 7 fm are required to achieve a result within 5% of the infinite-volume result at the physical pion mass. A variety of extrapolations are shown at different box sizes, providing a benchmark to guide future lattice QCD calculations of the magnetic polarizabilities. A relatively precise value for the physical magnetic polarizability of the neutron is presented, beta_n = 1.93(11)stat(8)sys x 10^-4 fm^3, which is in agreement with current experimental results.

J. M. M. Hall; D. B. Leinweber; R. D. Young

2015-02-19

101

Subvoxel processing: A method for reducing partial volume blurring with application to in vivo MR images of trabecular bone  

Microsoft Academic Search

Partial volume blurring precludes accurate measurement of structural dimensions in the limited-resolution regime in which image voxel size is larger than the typical structural element to be resolved. Since acquiring images at increased resolution often exacts an unacceptable signal-to-noise ratio (SNR) pen- alty, methods to alleviate the adverse effects of partial volume blurring are instrumental for the accurate measurement of

Scott N. Hwang; Felix W. Wehrli

2002-01-01

102

Partial volume correction for in vivo (23)Na-MRI data of the human brain.  

PubMed

The concentration of sodium is a functional cell parameter and absolute quantification can be interesting for diagnostical purposes. The accuracy of sodium magnetic resonance imaging ((23)Na-MRI) is strongly biased by partial volume effects (PVEs). Hence our purpose was to establish a partial volume correction (PVC) method for (23)Na-MRI. The existing geometric transfer matrix (GTM) correction method was transferred from positron emission tomography (PET) to (23)Na-MRI and tested in a phantom study. Different parameters, as well as accuracy of registration and segmentation were evaluated prior to first in vivo measurements. In vivo sodium data-sets of the human brain were obtained at B0=7T with a nominal spatial resolution of (3mm)(3) using a density adapted radial pulse sequence. A volunteer study with four healthy subjects was performed to measure partial volume (PV) corrected tissue sodium concentration (TSC) which was verified by means of an intrinsic correction control. In the phantom study the PVC algorithm yielded a good correction performance and reduced the discrepancy between the measured sodium concentration value and the expected value in the smallest compartments of the phantom by 11% to a mean PVE induced discrepancy of 5.7% after correction. The corrected in vivo data showed a reduction of PVE bias for the investigated compartments for all volunteers, resulting in a mean reduction of discrepancy between two separate CSF compartments from 36% to 7.6%. The absolute TSC for two separate CSF compartments (sulci, lateral ventricles), gray and white brain matter after correction were 129±8mmol/L, 138±4mmol/L, 48±1mmol/L and 43±3mmol/L, respectively. The applied PVC algorithm reduces the PV-bias in quantitative (23)Na-MRI. Accurate, high-resolution anatomical data is required to enable appropriate PVC. The algorithm and segmentation approach is robust and leads to reproducible results. PMID:25797831

Niesporek, Sebastian C; Hoffmann, Stefan H; Berger, Moritz C; Benkhedah, Nadia; Kujawa, Aaron; Bachert, Peter; Nagel, Armin M

2015-05-15

103

Partial specific volume and solvent interactions of amphipol A8-35 Yann Gohona  

E-print Network

) of the buoyant molar masses of particles in D2O and H2O solutions, obtained from sedimentation velocity (s. Measurements of density, sD/sH buoyant molar masses in H2O, D2O, and D2 18 O, and CMP of hydrogenated ultracentrifugation; Density; Small-angle neutron scattering Membrane proteins constitute about one-third

104

A Partial Volume Effect Correction Tailored for 18F-FDG-PET Oncological Studies  

PubMed Central

We have developed, optimized, and validated a method for partial volume effect (PVE) correction of oncological lesions in positron emission tomography (PET) clinical studies, based on recovery coefficients (RC) and on PET measurements of lesion-to-background ratio (L/Bm) and of lesion metabolic volume. An operator-independent technique, based on an optimised threshold of the maximum lesion uptake, allows to define an isocontour around the lesion on PET images in order to measure both lesion radioactivity uptake and lesion metabolic volume. RC are experimentally derived from PET measurements of hot spheres in hot background, miming oncological lesions. RC were obtained as a function of PET measured sphere-to-background ratio and PET measured sphere metabolic volume, both resulting from the threshold-isocontour technique. PVE correction of lesions of a diameter ranging from 10?mm to 40?mm and for measured L/Bm from 2 to 30 was performed using measured RC curves tailored at answering the need to quantify a large variety of real oncological lesions by means of PET. Validation of the PVE correction method resulted to be accurate (>89%) in clinical realistic conditions for lesion diameter > 1?cm, recovering >76% of radioactivity for lesion diameter < 1?cm. Results from patient studies showed that the proposed PVE correction method is suitable and feasible and has an impact on a clinical environment. PMID:24163819

Gallivanone, F.; Canevari, C.; Gianolli, L.; Salvatore, C.; Della Rosa, P. A.; Gilardi, M. C.; Castiglioni, I.

2013-01-01

105

IMPROVING MEASUREMENT OF FUNCTIONAL CONNECTIVITY THROUGH DECREASING PARTIAL VOLUME EFFECTS AT 7T  

PubMed Central

Several applications of fMRI at high field have taken advantage of the increased BOLD contrast to increase spatial resolution, but the potential benefits of higher fields for detecting and analyzing functional connectivity have largely been unexplored. We measured the influence of spatial resolution at 7T on estimates of functional connectivity through decreased partial volume averaging. Ten subjects were imaged at 7T with a range of spatial resolutions (1×1×2mm to 3×3×2mm) during performance of a finger tapping task and in the resting state. We found that resting state correlations within the sensory-motor system increase as voxel dimensions decreased from 3×3×2mm to 1×1×2mm, whereas connectivity to other brain regions was unaffected. This improvement occurred even as overall signal to noise ratios decrease. Our data suggest that this increase may be due to decreased partial volume averaging, and that functional connectivity within the primary seed region is heterogeneous on the scale of single voxels. PMID:21925611

Newton, Allen T.; Rogers, Baxter P.; Gore, John C.; Morgan, Victoria L.

2011-01-01

106

Partial volume correction using structural–functional synergistic resolution recovery: comparison with geometric transfer matrix method  

PubMed Central

We validated the use of a novel image-based method for partial volume correction (PVC), structural–functional synergistic resolution recovery (SFS-RR) for the accurate quantification of dopamine synthesis capacity measured using [18F]DOPA positron emission tomography. The bias and reliability of SFS-RR were compared with the geometric transfer matrix (GTM) method. Both methodologies were applied to the parametric maps of [18F]DOPA utilization rates (kicer). Validation was first performed by measuring repeatability on test–retest scans. The precision of the methodologies instead was quantified using simulated [18F]DOPA images. The sensitivity to the misspecification of the full-width-half-maximum (FWHM) of the scanner point-spread-function on both approaches was also assessed. In the in-vivo data, the kicer was significantly increased by application of both PVC procedures while the reliability remained high (intraclass correlation coefficients >0.85). The variability was not significantly affected by either PVC approach (<10% variability in both cases). The corrected kicer was significantly influenced by the FWHM applied in both the acquired and simulated data. This study shows that SFS-RR can effectively correct for partial volume effects to a comparable degree to GTM but with the added advantage that it enables voxelwise analyses, and that the FWHM used can affect the PVC result indicating the importance of accurately calibrating the FWHM used in the recovery model. PMID:23486292

Kim, Euitae; Shidahara, Miho; Tsoumpas, Charalampos; McGinnity, Colm J; Kwon, Jun Soo; Howes, Oliver D; Turkheimer, Federico E

2013-01-01

107

Partial volume correction using structural-functional synergistic resolution recovery: comparison with geometric transfer matrix method.  

PubMed

We validated the use of a novel image-based method for partial volume correction (PVC), structural-functional synergistic resolution recovery (SFS-RR) for the accurate quantification of dopamine synthesis capacity measured using [(18)F]DOPA positron emission tomography. The bias and reliability of SFS-RR were compared with the geometric transfer matrix (GTM) method. Both methodologies were applied to the parametric maps of [(18)F]DOPA utilization rates (ki(cer)). Validation was first performed by measuring repeatability on test-retest scans. The precision of the methodologies instead was quantified using simulated [(18)F]DOPA images. The sensitivity to the misspecification of the full-width-half-maximum (FWHM) of the scanner point-spread-function on both approaches was also assessed. In the in-vivo data, the ki(cer) was significantly increased by application of both PVC procedures while the reliability remained high (intraclass correlation coefficients >0.85). The variability was not significantly affected by either PVC approach (<10% variability in both cases). The corrected ki(cer) was significantly influenced by the FWHM applied in both the acquired and simulated data. This study shows that SFS-RR can effectively correct for partial volume effects to a comparable degree to GTM but with the added advantage that it enables voxelwise analyses, and that the FWHM used can affect the PVC result indicating the importance of accurately calibrating the FWHM used in the recovery model. PMID:23486292

Kim, Euitae; Shidahara, Miho; Tsoumpas, Charalampos; McGinnity, Colm J; Kwon, Jun Soo; Howes, Oliver D; Turkheimer, Federico E

2013-06-01

108

Effect of KCl and KNO3 on Partial Molal Volumes and Partial Molal Compressibilities of Some Amino Acids at Different Temperatures  

NASA Astrophysics Data System (ADS)

Density ( ?) and ultrasonic velocity ( u) values of amino acids l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and 2M aqueous KNO3 solutions have been measured as a function of amino acid concentration at different temperatures (298.15 K, 303.15 K, 308.15 K, 313.15 K, 318.15 K, and 323.15 K). Using the ? and u data, partial molal volume ({?_v^o}) and partial molal isentropic compressibility ({?_k^o }) values have been computed. The increase in partial molal volume with temperature has been attributed to the volume expansion of hydrated zwitterions. The {?_v^o} and {?_k^o} values of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO3 solutions have been found to be larger than the corresponding values in water. The larger partial molal volumes of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO3 solutions have been ascribed to the formation of ‘zwitterion-K+/Cl-/NO{3/-}’ and ‘K+/Cl-/NO{3/-}-water dipole’ aggregates in solutions. The formation of these entities in solutions causes the release of water associated with zwitterions to the bulk water. The larger partial molal compressibilities of l-alanine-/ l-proline-/ l-valine-/ l-leucine-2M aqueous KCl/KNO3 solutions than the corresponding values in water have been attributed to the formation of ‘zwitterion-ion’ and ‘ion-water dipole’ incompressible entities in solutions.

Riyazuddeen; Khan, Imran

2009-04-01

109

Dedicated breast computed tomography: Volume image denoising via a partial-diffusion equation based technique  

PubMed Central

Dedicated breast computed tomography (CT) imaging possesses the potential for improved lesion detection over conventional mammograms, especially for women with dense breasts. The breast CT images are acquired with a glandular dose comparable to that of standard two-view mammography for a single breast. Due to dose constraints, the reconstructed volume has a non-negligible quantum noise when thin section CT slices are visualized. It is thus desirable to reduce noise in the reconstructed breast volume without loss of spatial resolution. In this study, partial diffusion equation (PDE) based denoising techniques specifically for breast CT were applied at different steps along the reconstruction process and it was found that denoising performed better when applied to the projection data rather than reconstructed data. Simulation results from the contrast detail phantom show that the PDE technique outperforms Wiener denoising as well as adaptive trimmed mean filter. The PDE technique increases its performance advantage relative to Wiener techniques when the photon fluence is reduced. With the PDE technique, the sensitivity for lesion detection using the contrast detail phantom drops by less than 7% when the dose is cut down to 40% of the two-view mammography. For subjective evaluation, the PDE technique was applied to two human subject breast data sets acquired on a prototype breast CT system. The denoised images had appealing visual characteristics with much lower noise levels and improved tissue textures while maintaining sharpness of the original reconstructed volume. PMID:18561671

Xia, Jessie Q.; Lo, Joseph Y.; Yang, Kai; Floyd, Carey E.; Boone, John M.

2008-01-01

110

5-HT1A Receptors Are Reduced in Temporal Lobe Epilepsy After Partial-Volume Correction  

PubMed Central

Preclinical studies suggest that serotonin 1A receptors (5-HT1A) play a role in temporal lobe epilepsy (TLE). Previous PET studies reported decreased 5-HT1A binding ipsilateral to epileptic foci but did not correct for the partial-volume effect (PVE) due to structural atrophy. Methods: We used PET with 18F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl-N-(2-pyridyl)cyclohexanecarboxamide (18F-FCWAY), a 5-HT1A receptor antagonist, to study 22 patients with TLE and 10 control subjects. In patients, 18F-FDG scans also were performed. An automated MR-based partial-volume correction (PVC) algorithm was applied. Psychiatric symptoms were assessed with the Beck Depression Inventory Scale.Results: Before PVC, significant (uncorrected P<0.05) reductions of 18F-FCWAY binding potential (BP) were detected in both mesial and lateral temporal structures, mainly ipsilateral to the seizure focus, in the insula, and in the raphe. Group differences were maximal in ipsilateral mesial temporal regions (corrected P<0.05). After PVC, differences in mesial, but not lateral, temporal structures and in the insula remained highly significant (corrected P<0.05). Signifi-cant (uncorrected P<0.05) BP reductions were also detected in TLE patients with normal MR images (n = 6), in mesial temporal structures. After PVC, asymmetries in BP remained significantly greater than for glucose metabolism in hippocampus and parahippocampus. There was a significant inverse relation between the Beck Depression score and the ipsilateral hippocampal BP, both before and after PVC. Conclusion: Our study shows that in TLE patients, reductions of 5-HT1A receptor binding in mesial temporal structures and insula are still significant after PVC. In contrast, partial-volume effects may be an important contributor to 5-HT1A receptor-binding reductions in lateral temporal lobe. Reduction of 5-HT1A receptors in the ipsilateral hippocampus may contribute to depressive symptoms in TLE patients. PMID:16000281

Giovacchini, Giampiero; Toczek, Maria T.; Bonwetsch, Robert; Bagic, Anto; Lang, Lixin; Fraser, Charles; Reeves-Tyer, Pat; Herscovitch, Peter; Eckelman, William C.; Carson, Richard E.

2005-01-01

111

Edge-based partial volume averaging estimation for FLAIR MRI with white matter lesions.  

PubMed

Through the combination of intensity and fuzzy edge strength measures, a new partial volume averaging (PVA) quantification technique for FLAIR MRI with white matter lesions (WML) is developed. It is focused on an edge-based approach, which "probes" for PVA voxels via a global estimate for the change in the proportion of tissues ?'. This estimate is refined according to a probabilistic threshold, and the result is decoded to find the proportion of tissues fraction ? - the percentage of one tissue found in a mixture voxel. The results from several images are shown illustrating how the technique may be used to segment PVA and pure tissue classes. The result is a non-model based approach to the detection and quantification of PVA. PMID:21097137

Khademi, April; Venetsanopoulos, Anastasios; Moody, Alan R

2010-01-01

112

MRI-guided brain PET image filtering and partial volume correction.  

PubMed

Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and (18)F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data. PMID:25575248

Yan, Jianhua; Lim, Jason Chu-Shern; Townsend, David W

2015-02-01

113

MRI-guided brain PET image filtering and partial volume correction  

NASA Astrophysics Data System (ADS)

Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and 18F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

Yan, Jianhua; Chu-Shern Lim, Jason; Townsend, David W.

2015-02-01

114

Surface-based partial-volume correction for high-resolution PET.  

PubMed

Tissue radioactivity concentrations, measured with positron emission tomography (PET) are subject to partial volume effects (PVE) due to the limited spatial resolution of the scanner. Last generation high-resolution PET cameras with a full width at half maximum (FWHM) of 2-4mm are less prone to PVEs than previous generations. Corrections for PVEs are still necessary, especially when studying small brain stem nuclei or small variations in cortical neuroreceptor concentrations which may be related to cytoarchitectonic differences. Although several partial-volume correction (PVC) algorithms exist, these are frequently based on a priori assumptions about tracer distribution or only yield corrected values of regional activity concentrations without providing PVE corrected images. We developed a new iterative deconvolution algorithm (idSURF) for PVC of PET images that aims to overcome these limitations by using two innovative techniques: 1) the incorporation of anatomic information from a cortical gray matter surface representation, extracted from magnetic resonance imaging (MRI) and 2) the use of anatomically constrained filtering to attenuate noise. PVE corrected images were generated with idSURF implemented into a non-interactive processing pipeline. idSURF was validated using simulated and clinical PET data sets and compared to a frequently used standard PVC method (Geometric Transfer Matrix: GTM). The results on simulated data sets show that idSURF consistently recovers accurate radiotracer concentrations within 1-5% of true values. Both radiotracer concentrations and non-displaceable binding potential (BPnd) values derived from clinical PET data sets with idSURF were highly correlated with those obtained with the standard PVC method (R(2) = 0.99, error = 0%-3.2%). These results suggest that idSURF is a valid and potentially clinically useful PVC method for automatic processing of large numbers of PET data sets. PMID:25175542

Funck, Thomas; Paquette, Caroline; Evans, Alan; Thiel, Alexander

2014-11-15

115

Comparison of Pre/Post-Operative CT Image Volumes to Preoperative Digitization of Partial Hepatectomies: A Feasibility  

E-print Network

change comparisons as a means to evaluate the accuracy of preoperative surgical plans. Keywords: Image that preoperative planning using three-dimensional patient-specific models facilitates the selection of optimalComparison of Pre/Post-Operative CT Image Volumes to Preoperative Digitization of Partial

Miga, Michael I.

116

Differences in Effective Target Volume Between Various Techniques of Accelerated Partial Breast Irradiation  

SciTech Connect

Purpose: Different cavity expansions are used to define the clinical target volume (CTV) for accelerated partial breast irradiation (APBI) delivered via balloon brachytherapy (1 cm) vs. three-dimensional conformal radiotherapy (3D-CRT) (1.5 cm). Previous studies have argued that the CTVs generated by these different margins are effectively equivalent. In this study, we use deformable registration to assess the effective CTV treated by balloon brachytherapy on clinically representative 3D-CRT planning images. Methods and Materials: Ten patients previously treated with the MammoSite were studied. Each patient had two computed tomography (CT) scans, one acquired before and one after balloon implantation. In-house deformable registration software was used to deform the MammoSite CTV onto the balloonless CT set. The deformed CTV was validated using anatomical landmarks common to both CT scans. Results: The effective CTV treated by the MammoSite was on average 7% {+-} 10% larger and 38% {+-} 4% smaller than 3D-CRT CTVs created using uniform expansions of 1 and 1.5 cm, respectively. The average effective CTV margin was 1.0 cm, the same as the actual MammoSite CTV margin. However, the effective CTV margin was nonuniform and could range from 5 to 15 mm in any given direction. Effective margins <1 cm were attributable to poor cavity-balloon conformance. Balloon size relative to the cavity did not significantly correlate with the effective margin. Conclusion: In this study, the 1.0-cm MammoSite CTV margin treated an effective volume that was significantly smaller than the 3D-CRT CTV based on a 1.5-cm margin.

Shaitelman, Simona F.; Vicini, Frank A.; Grills, Inga S.; Martinez, Alvaro A.; Yan Di [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Kim, Leonard H., E-mail: lkim@beaumonthospitals.com [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

2012-01-01

117

A multiresolution image based approach for correction of partial volume effects in emission tomography.  

PubMed

Partial volume effects (PVEs) are consequences of the limited spatial resolution in emission tomography. They lead to a loss of signal in tissues of size similar to the point spread function and induce activity spillover between regions. Although PVE can be corrected for by using algorithms that provide the correct radioactivity concentration in a series of regions of interest (ROIs), so far little attention has been given to the possibility of creating improved images as a result of PVE correction. Potential advantages of PVE-corrected images include the ability to accurately delineate functional volumes as well as improving tumour-to-background ratio, resulting in an associated improvement in the analysis of response to therapy studies and diagnostic examinations, respectively. The objective of our study was therefore to develop a methodology for PVE correction not only to enable the accurate recuperation of activity concentrations, but also to generate PVE-corrected images. In the multiresolution analysis that we define here, details of a high-resolution image H (MRI or CT) are extracted, transformed and integrated in a low-resolution image L (PET or SPECT). A discrete wavelet transform of both H and L images is performed by using the "à trous" algorithm, which allows the spatial frequencies (details, edges, textures) to be obtained easily at a level of resolution common to H and L. A model is then inferred to build the lacking details of L from the high-frequency details in H. The process was successfully tested on synthetic and simulated data, proving the ability to obtain accurately corrected images. Quantitative PVE correction was found to be comparable with a method considered as a reference but limited to ROI analyses. Visual improvement and quantitative correction were also obtained in two examples of clinical images, the first using a combined PET/CT scanner with a lymphoma patient and the second using a FDG brain PET and corresponding T1-weighted MRI in an epileptic patient. PMID:16552110

Boussion, N; Hatt, M; Lamare, F; Bizais, Y; Turzo, A; Cheze-Le Rest, C; Visvikis, D

2006-04-01

118

Spinal Cord Tolerance to Single-Fraction Partial-Volume Irradiation: A Swine Model  

SciTech Connect

Purpose: To determine the spinal cord tolerance to single-fraction, partial-volume irradiation in swine. Methods and Materials: A 5-cm-long cervical segment was irradiated in 38-47-week-old Yucatan minipigs using a dedicated, image-guided radiosurgery linear accelerator. The radiation was delivered to a cylindrical volume approximately 5 cm in length and 2 cm in diameter that was positioned lateral to the cervical spinal cord, resulting in a dose distribution with the 90%, 50%, and 10% isodose lines traversing the ipsilateral, central, and contralateral spinal cord, respectively. The dose was prescribed to the 90% isodose line. A total of 26 pigs were stratified into eight dose groups of 12-47 Gy. The mean maximum spinal cord dose was 16.9 {+-} 0.1, 18.9 {+-} 0.1, 21.0 {+-} 0.1, 23.0 {+-} 0.2, and 25.3 {+-} 0.3 Gy in the 16-, 18-, 20-, 22-, and 24-Gy dose groups, respectively. The mean percentage of spinal cord volumes receiving {>=}10 Gy for the same groups were 43% {+-} 3%, 48% {+-} 4%, 51% {+-} 2%, 57% {+-} 2%, and 59% {+-} 4%. The study endpoint was motor neurologic deficit determined by a change in gait during a 1-year follow-up period. Results: A steep dose-response curve was observed with a median effective dose for the maximum dose point of 20.0 Gy (95% confidence interval, 18.3-21.7). Excellent agreement was observed between the occurrence of neurologic change and the presence of histologic change. All the minipigs with motor deficits showed some degree of demyelination and focal white matter necrosis on the irradiated side, with relative sparing of the gray matter. The histologic findings were unremarkable in the minipigs with normal neurologic status. Conclusions: Our results have indicated that for a dose distribution with a steep lateral gradient, the pigs had a lower median effective dose for paralysis than has been observed in rats and more closely resembles that for rats, mice, and guinea pigs receiving uniform spinal cord irradiation.

Medin, Paul M., E-mail: Paul.medin@utsouthwestern.ed [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Foster, Ryan D. [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Kogel, Albert J. van der [Department of Radiation Oncology, Radboud University Medical Center Nijmegen, Nijmegen (Netherlands); Sayre, James W. [Department of Biostatistics, University of California, Los Angeles, School of Medicine, Los Angeles, CA (United States); Department of Radiology, University of California, Los Angeles, School of Medicine, Los Angeles, CA (United States); McBride, William H. [Department of Radiation Oncology, University of California, Los Angeles, School of Medicine, Los Angeles, CA (United States); Solberg, Timothy D. [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States)

2011-01-01

119

Region-Based Partial Volume Correction Techniques for PET Imaging: Sinogram Implementation and Robustness  

PubMed Central

Background/Purpose. Limited spatial resolution of positron emission tomography (PET) requires partial volume correction (PVC). Region-based PVC methods are based on geometric transfer matrix implemented either in image-space (GTM) or sinogram-space (GTMo), both with similar performance. Although GTMo is slower, it more closely simulates the 3D PET image acquisition, accounts for local variations of point spread function, and can be implemented for iterative reconstructions. A recent image-based symmetric GTM (sGTM) has shown improvement in noise characteristics and robustness to misregistration over GTM. This study implements the sGTM method in sinogram space (sGTMo), validates it, and evaluates its performance. Methods. Two 3D sphere and brain digital phantoms and a physical sphere phantom were used. All four region-based PVC methods (GTM, GTMo, sGTM, and sGTMo) were implemented and their performance was evaluated. Results. All four PVC methods had similar accuracies. Both noise propagation and robustness of the sGTMo method were similar to those of sGTM method while they were better than those of GTMo method especially for smaller objects. Conclusion. The sGTMo was implemented and validated. The performance of the sGTMo in terms of noise characteristics and robustness to misregistration is similar to that of the sGTM method and improved compared to the GTMo method. PMID:24455241

Szilagyi, Gregory M.; Kusano, Maggie; Poon, Ian; Caldwell, Curtis

2013-01-01

120

Bi-exponential magnetic resonance signal model for partial volume computation  

PubMed Central

Accurate quantification of small structures in magnetic resonance (MR) images is often limited by partial volume (PV) effects which arise when more than one tissue type is present in a voxel. PV may be critical when dealing with changes in brain anatomy as the considered structures such as gray matter (GM) are of the similar size as the MR spatial resolution. To overcome the limitations imposed by PV effects and achieve subvoxel accuracy different methods have been proposed. Here, we describe a method to compute PV by modeling the MR signal with a biexponential linear combination representing the contribution of at most two tissues in each voxel. In a first step, we estimated the parameters (T1, T2 and Proton Density) per tissue. Then, based on the bi-exponential formulation one can retrieve fractional contents by solving a linear system of two equations with two unknowns, namely tissue magnetizations. Preliminary tests were conducted on images acquired on a specially designed physical phantom for the study of PV effects. Further, the model was tested on BrainWeb simulated brain images to estimate GM and white matter (WM) PV effects. Root Mean Squared Error was computed between the BrainWeb ground truth and the obtained GM and WM PV maps. The proposed method outperformed traditionally used methods by 33% and 34% in GM and WM, respectively. PMID:23285556

Duché, Quentin; Acosta, Oscar; Gambarota, Giulio; Merlet, Isabelle; Salvado, Olivier; Saint-Jalmes, Hervé

2012-01-01

121

Ectopic molar pregnancy: a case report.  

PubMed

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

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

2012-01-01

122

Ectopic molar pregnancy: a case report  

PubMed Central

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

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

2012-01-01

123

Gray matter myelination of 1555 human brains using partial volume corrected MRI images.  

PubMed

The myelin content of the cortex changes over the human lifetime and aberrant cortical myelination is associated with diseases such as schizophrenia and multiple sclerosis. Recently magnetic resonance imaging (MRI) techniques have shown potential in differentiating between myeloarchitectonically distinct cortical regions in vivo. Here we introduce a new algorithm for correcting partial volume effects present in mm-scale MRI images which was used to investigate the myelination pattern of the cerebral cortex in 1555 clinically normal subjects using the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images. A significant linear cross-sectional age increase in T1w/T2w estimated myelin was detected across an 18 to 35 year age span (highest value of ~ 1%/year compared to mean T1w/T2w myelin value at 18 years). The cortex was divided at mid-thickness and the value of T1w/T2w myelin calculated for the inner and outer layers separately. The increase in T1w/T2w estimated myelin occurs predominantly in the inner layer for most cortical regions. The ratio of the inner and outer layer T1w/T2w myelin was further validated using high-resolution in vivo MRI scans and also a high-resolution MRI scan of a postmortem brain. Additionally, the relationships between cortical thickness, curvature and T1w/T2w estimated myelin were found to be significant, although the relationships varied across the cortex. We discuss these observations as well as limitations of using the T1w/T2w ratio as an estimate of cortical myelin. PMID:25449739

Shafee, Rebecca; Buckner, Randy L; Fischl, Bruce

2015-01-15

124

When Structure Affects Function – The Need for Partial Volume Effect Correction in Functional and Resting State Magnetic Resonance Imaging Studies  

PubMed Central

Both functional and also more recently resting state magnetic resonance imaging have become established tools to investigate functional brain networks. Most studies use these tools to compare different populations without controlling for potential differences in underlying brain structure which might affect the functional measurements of interest. Here, we adapt a simulation approach combined with evaluation of real resting state magnetic resonance imaging data to investigate the potential impact of partial volume effects on established functional and resting state magnetic resonance imaging analyses. We demonstrate that differences in the underlying structure lead to a significant increase in detected functional differences in both types of analyses. Largest increases in functional differences are observed for highest signal-to-noise ratios and when signal with the lowest amount of partial volume effects is compared to any other partial volume effect constellation. In real data, structural information explains about 25% of within-subject variance observed in degree centrality – an established resting state connectivity measurement. Controlling this measurement for structural information can substantially alter correlational maps obtained in group analyses. Our results question current approaches of evaluating these measurements in diseased population with known structural changes without controlling for potential differences in these measurements. PMID:25460595

Dukart, Juergen; Bertolino, Alessandro

2014-01-01

125

Accuracy of partial volume effect correction in clinical molecular imaging of dopamine transporter using SPECT  

NASA Astrophysics Data System (ADS)

ObjectivesPartial volume effect (PVE) is a major source of bias in brain SPECT imaging of dopamine transporter. Various PVE corrections (PVC) making use of anatomical data have been developed and yield encouraging results. However, their accuracy in clinical data is difficult to demonstrate because the gold standard (GS) is usually unknown. The objective of this study was to assess the accuracy of PVC. MethodTwenty-three patients underwent MRI and 123I-FP-CIT SPECT. The binding potential (BP) values were measured in the striata segmented on the MR images after coregistration to SPECT images. These values were calculated without and with an original PVC. In addition, for each patient, a Monte Carlo simulation of the SPECT scan was performed. For these simulations where true simulated BP values were known, percent biases in BP estimates were calculated. For the real data, an evaluation method that simultaneously estimates the GS and a quadratic relationship between the observed and the GS values was used. It yields a surrogate mean square error (sMSE) between the estimated values and the estimated GS values. ResultsThe averaged percent difference between BP measured for real and for simulated patients was 0.7±9.7% without PVC and was -8.5±14.5% with PVC, suggesting that the simulated data reproduced the real data well enough. For the simulated patients, BP was underestimated by 66.6±9.3% on average without PVC and overestimated by 11.3±9.5% with PVC, demonstrating the greatest accuracy of BP estimates with PVC. For the simulated data, sMSE were 27.3 without PVC and 0.90 with PVC, confirming that our sMSE index properly captured the greatest accuracy of BP estimates with PVC. For the real patient data, sMSE was 50.8 without PVC and 3.5 with PVC. These results were consistent with those obtained on the simulated data, suggesting that for clinical data, and despite probable segmentation and registration errors, BP were more accurately estimated with PVC than without. ConclusionPVC was very efficient to greatly reduce the error in BP estimates in clinical imaging of dopamine transporter.

Soret, Marine; Alaoui, Jawad; Koulibaly, Pierre M.; Darcourt, Jacques; Buvat, Irène

2007-02-01

126

Anatomical structural network analysis of human brain using partial correlations of gray matter volumes  

Microsoft Academic Search

Structural connectivity in human brain has been studied by modeling the statistical dependence between features of cortical regions, such as gray matter thickness. Statistical correlations between gray matter thickness have been mainly used as a metric to study this dependence. In this paper, we propose the use of partial correlations instead of Pearson correlation for inferring the brain structural connectivity

Anand A. Joshi; Shantanu H. Joshi; Ivo D. Dinov; David W. Shattuck; Richard M. Leahy; Arthur W. Toga

2010-01-01

127

Limitation in tidal volume expansion partially determines the intensity of physical activity in COPD.  

PubMed

In patients with chronic obstructive pulmonary disease (COPD), reduced levels of daily physical activity are associated with the degree of impairment in lung, peripheral muscle, and central hemodynamic function. There is, however, limited evidence as to whether limitations in tidal volume expansion also, importantly, determine daily physical activity levels in COPD. Eighteen consecutive patients with COPD [9 active (forced expiratory volume in 1 s, FEV1: 1.59 ± 0.64 l) with an average daily movement intensity >1.88 m/s(2) and 9 less active patients (FEV1: 1.16 ± 0.41 l) with an average intensity <1.88 m/s(2)] underwent a 4-min treadmill test at a constant speed corresponding to each individual patient's average movement intensity, captured by a triaxial accelerometer during a preceding 7-day period. When chest wall volumes, captured by optoelectronic plethysmography, were expressed relative to comparable levels of minute ventilation (ranging between 14.5 ± 4.3 to 33.5 ± 4.4 l/min), active patients differed from the less active ones in terms of the lower increase in end-expiratory chest wall volume (by 0.15 ± 0.17 vs. 0.45 ± 0.21 l), the greater expansion in tidal volume (by 1.76 ± 0.58 vs. 1.36 ± 0.24 l), and the larger inspiratory reserve chest wall volume (IRVcw: by 0.81 ± 0.25 vs. 0.39 ± 0.27 l). IRVcw (r(2) = 0.420), expiratory flow (r(2) change = 0.174), and Borg dyspnea score (r(2) change = 0.123) emerged as the best contributors, accounting for 71.7% of the explained variance in daily movement intensity. Patients with COPD exhibiting greater ability to expand tidal volume and to maintain adequate inspiratory reserve volume tend to be more physically active. Thus interventions aiming at mitigating restrictions on operational chest wall volumes are expected to enhance daily physical activity levels in COPD. PMID:25398190

Kortianou, Eleni A; Aliverti, Andrea; Louvaris, Zafeiris; Vasilopoulou, Maroula; Nasis, Ioannis; Asimakos, Andreas; Zakynthinos, Spyros; Vogiatzis, Ioannis

2015-01-01

128

A review of partial volume correction techniques for emission tomography and their applications in neurology, cardiology and oncology.  

PubMed

Accurate quantification in PET and SPECT requires correction for a number of physical factors, such as photon attenuation, Compton scattering and random coincidences (in PET). Another factor affecting quantification is the limited spatial resolution. While considerable effort has gone into development of routine correction techniques for the former factors, less attention has been paid to the latter. Spatial resolution-related effects, referred to as 'partial volume effects' (PVEs), depend not only on the characteristics of the imaging system but also on the object and activity distribution. Spatial and/or temporal variations in PVE can often be confounding factors. Partial volume correction (PVC) could in theory be achieved by some kind of inverse filtering technique, reversing the effect of the system PSF. However, these methods are limited, and usually lead to noise-amplification or image artefacts. Some form of regularization is therefore needed, and this can be achieved using information from co-registered anatomical images, such as CT or MRI. The purpose of this paper is to enhance understanding of PVEs and to review possible approaches for PVC. We also present a review of clinical applications of PVC within the fields of neurology, cardiology and oncology, including specific examples. PMID:23073343

Erlandsson, Kjell; Buvat, Irène; Pretorius, P Hendrik; Thomas, Benjamin A; Hutton, Brian F

2012-11-01

129

Partial volume tissue classification of multichannel magnetic resonance images-a mixel model  

Microsoft Academic Search

A single volume element (voxel) in a medical image may be composed of a mixture of multiple tissue types. The authors call voxels which contain multiple tissue classes mixels. A statistical mixel image model based on Markov random field (MRF) theory and an algorithm for the classification of mixels are presented. The authors concentrate on the classification of multichannel magnetic

Hwan SOO Choi; David R. Haynor; Yongmin Kim

1991-01-01

130

Solutions : WtPercentToMolarity (4 Variations)  

NSDL National Science Digital Library

A common concentration unit used commercially is percent weight per volume (%W/V) which is the number of grams of solute in 100 mL of solution. A bottle of vinegar contains 5 %W/V acetic acid (CH 3 COOH). What is the molar concentration of acetic acid in the vinegar?

131

Molarization of Mandibular Second Premolar  

PubMed Central

ABSTRACT 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

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

2014-01-01

132

Molarization of mandibular second premolar.  

PubMed

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

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

2014-05-01

133

Molar Incisor Hypomineralization, Prevalence, and Etiology  

PubMed Central

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. PMID:24949012

Allazzam, Sulaiman Mohammed; Alaki, Sumer Madani; El Meligy, Omar Abdel Sadek

2014-01-01

134

Molar incisor hypomineralization, prevalence, and etiology.  

PubMed

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. PMID:24949012

Allazzam, Sulaiman Mohammed; Alaki, Sumer Madani; El Meligy, Omar Abdel Sadek

2014-01-01

135

How Neanderthal molar teeth grew  

Microsoft Academic Search

Growth and development are both fundamental components of demographic structure and life history strategy. Together with information about developmental timing they ultimately contribute to a better understanding of Neanderthal extinction. Primate molar tooth development tracks the pace of life history evolution most closely, and tooth histology reveals a record of birth as well as the timing of crown and root

Roberto Macchiarelli; Luca Bondioli; André Debénath; Arnaud Mazurier; Jean-François Tournepiche; Wendy Birch; M. Christopher Dean

2006-01-01

136

MRI data driven partial volume effects correction in PET imaging using 3D local multi-resolution analysis  

NASA Astrophysics Data System (ADS)

PET partial volume effects (PVE) resulting from the limited resolution of PET scanners is still a quantitative issue that PET/MRI scanners do not solve by themselves. A recently proposed voxel-based locally adaptive 3D multi-resolution PVE correction based on the mutual analysis of wavelet decompositions was applied on 12 clinical 18F-FLT PET/T1 MRI images of glial tumors, and compared to a PET only voxel-wise iterative deconvolution approach. Quantitative and qualitative results demonstrated the interest of exploiting PET/MRI information with higher uptake increases (19±8% vs. 11±7%, p=0.02), as well as more convincing visual restoration of details within tumors with respect to deconvolution of the PET uptake only. Further studies are now required to demonstrate the accuracy of this restoration with histopathological validation of the uptake in tumors.

Le Pogam, Adrien; Lamare, Frederic; Hatt, Mathieu; Fernandez, Philippe; Le Rest, Catherine Cheze; Visvikis, Dimitris

2013-02-01

137

Partial hydatidiform mole and coexisting viable twin pregnancy.  

PubMed

Twin partial hydatidiform molar pregnancy with a viable fetus is an uncommon occurrence. Presentations of molar pregnancies include vaginal bleeding, unusually elevated ?-human chorionic gonadotropin level, and preeclampsia. Previous descriptions of twin molar and fetus pregnancies in the literature have been described in the outpatient obstetric setting. We present a case of partial molar pregnancy with a viable fetus detected with emergency ultrasound in a pediatric emergency department. PMID:24300477

Tay, Ee Tein

2013-12-01

138

Comparing a volume based template approach and ultrasound guided freehand approach in multicatheter interstitial accelerated partial breast irradiation  

PubMed Central

Purpose Currently, there are two described methods of catheter insertion for women undergoing multicatheter interstitial accelerated partial breast irradiation (APBI). These are a volume based template approach (template) and a non-template ultrasound guidance freehand approach (non-template). We aim to compare dosimetric endpoints between the template and non-template approach. Material and methods Twenty patients, who received adjuvant multicatheter interstitial APBI between August 2008 to March 2010 formed the study cohort. Dosimetric planning was based on the RTOG 04-13 protocol. For standardization, the planning target volume evaluation (PTV-Eval) and organs at risk were contoured with the assistance of the attending surgeon. Dosimetric endpoints include D90 of the PTV-Eval, Dose Homogeneity Index (DHI), V200, maximum skin dose (MSD), and maximum chest wall dose (MCD). A median of 18 catheters was used per patient. The dose prescribed was 34 Gy in 10 fractions BID over 5 days. Results The average breast volume was 846 cm3 (526-1384) for the entire cohort and there was no difference between the two groups (p = 0.6). Insertion time was significantly longer for the non-template approach (mean 150 minutes) compared to the template approach (mean: 90 minutes) (p = 0.02). The planning time was also significantly longer for the non-template approach (mean: 240 minutes) compared to the template approach (mean: 150 minutes) (p < 0.01). The template approach yielded a higher D90 (mean: 95%) compared to the non-template approach (mean: 92%) (p < 0.01). There were no differences in DHI (p = 0.14), V200 (p = 0.21), MSD (p = 0.7), and MCD (p = 0.8). Conclusions Compared to the non-template approach, the template approach offered significant shorter insertion and planning times with significantly improved dosimetric PTV-Eval coverage without significantly compromising organs at risk dosimetrically. PMID:25097558

Koh, Vicky Y.; Buhari, Shaik A.; Tan, Poh Wee; Tan, Yun Inn; Leong, Yuh Fun; Earnest, Arul

2014-01-01

139

Treatment planning considerations for molar uprighting.  

PubMed

Molar uprighting cases require individualized treatment planning depending upon condition of ridge, growth pattern of patient, periodontal condition, lower facial height, position of third molar and anchorage. Uprighting of molar was done in two cases--effectively using simple tip back spring in one case and implant in another. PMID:25745724

Kaur, Harsimrat; Pavithra, U S; Shabeer, N N; Reji, Abraham

2014-01-01

140

Molar versus as a paradigm clash.  

PubMed

The molar view of behavior arose in response to the demonstrated inadequacy of explanations based on contiguity. Although Dinsmoor's (2001) modifications to two-factor theory render it irrefutable, a more basic criticism arises when we see that the molar and molecular views differ paradigmatically. The molar view has proven more productive. PMID:11453623

Baum, W M

2001-05-01

141

Partial volume effect correction in PET using regularized iterative deconvolution with variance control based on local topology  

NASA Astrophysics Data System (ADS)

Correcting positron emission tomography (PET) images for the partial volume effect (PVE) due to the limited resolution of PET has been a long-standing challenge. Various approaches including incorporation of the system response function in the reconstruction have been previously tested. We present a post-reconstruction PVE correction based on iterative deconvolution using a 3D maximum likelihood expectation-maximization (MLEM) algorithm. To achieve convergence we used a one step late (OSL) regularization procedure based on the assumption of local monotonic behavior of the PET signal following Alenius et al. This technique was further modified to selectively control variance depending on the local topology of the PET image. No prior 'anatomic' information is needed in this approach. An estimate of the noise properties of the image is used instead. The procedure was tested for symmetric and isotropic deconvolution functions with Gaussian shape and full width at half-maximum (FWHM) ranging from 6.31 mm to infinity. The method was applied to simulated and experimental scans of the NEMA NU 2 image quality phantom with the GE Discovery LS PET/CT scanner. The phantom contained uniform activity spheres with diameters ranging from 1 cm to 3.7 cm within uniform background. The optimal sphere activity to variance ratio was obtained when the deconvolution function was replaced by a step function few voxels wide. In this case, the deconvolution method converged in ~3-5 iterations for most points on both the simulated and experimental images. For the 1 cm diameter sphere, the contrast recovery improved from 12% to 36% in the simulated and from 21% to 55% in the experimental data. Recovery coefficients between 80% and 120% were obtained for all larger spheres, except for the 13 mm diameter sphere in the simulated scan (68%). No increase in variance was observed except for a few voxels neighboring strong activity gradients and inside the largest spheres. Testing the method for patient images increased the visibility of small lesions in non-uniform background and preserved the overall image quality. Regularized iterative deconvolution with variance control based on the local properties of the PET image and on estimated image noise is a promising approach for partial volume effect corrections in PET.

Kirov, A. S.; Piao, J. Z.; Schmidtlein, C. R.

2008-05-01

142

Dependence of the volume and viscosity of naphthalene-ethanol-octane solutions on composition at 298 K  

NASA Astrophysics Data System (ADS)

The solubility of naphthalene in ethanol-octane mixtures was measured by the isothermal saturation method. The solution densities were determined and the partial and apparent molar volumes of naphthalene were calculated. The viscosity was measured with an Ubbelohde viscosimeter with a suspended level. All measurements were performed at 298.15 K. The results were discussed based on interactions in solution.

Eliseeva, O. V.; Dyshin, A. A.; Kiselev, M. G.

2013-03-01

143

A study of shape-dependent partial volume correction in pet imaging using ellipsoidal phantoms fabricated via rapid prototyping  

NASA Astrophysics Data System (ADS)

Positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (FDG) is being increasingly recognized as an important tool for quantitative assessment of tumor response because of its ability to capture functional information about the tumor's metabolism. However, despite many advances in PET technology, measurements of tumor radiopharmaceutical uptake in PET are still challenged by issues of accuracy and consistency, thereby compromising the use of PET as a surrogate endpoint in clinical trials. One limiting component of the overall uncertainty in PET is the relatively poor spatial resolution of the images which directly affects the accuracy of the tumor radioactivity measurements. These spatial resolution effects, colloquially known as the partial volume effect (PVE), are a function of the characteristics of the scanner as well as the tumor being imaged. Previous efforts have shown that the PVE depends strongly on the tumor volume and the background-to-tumor activity concentration ratio. The PVE is also suspected to be a function of tumor shape, although to date no systematic study of this effect has been performed. This dissertation seeks to help fill the gap in the current knowledge about the shape-dependence of the PVE by attempting to quantify, through both theoretical calculation and experimental measurement, the magnitude of the shape effect for ellipsoidal tumors. An experimental investigation of the tumor shape effect necessarily requires tumor phantoms of multiple shapes. Hence, a prerequisite for this research was the design and fabrication of hollow tumor phantoms which could be filled uniformly with radioactivity and imaged on a PET scanner. The phantom fabrication was achieved with the aid of stereolithography and included prolate ellipsoids of various axis ratios. The primary experimental method involved filling the tumor phantoms with solutions of 18F whose activity concentrations were known and traceable to primary radioactivity standards held by the National Institute of Standards and Technology (NIST). The tumor phantoms were then placed inside a Jaszczak cylinder (representing the human body) and imaged on a PET scanner located at NIST. This experimental approach allowed for the testing of: (1) The relative difference between tumors phantoms of different shapes, but same volume; (2) The overall accuracy of the PET measurements in terms of a ground truth reference value. Theoretical calculations of the tumor shape effect were also performed by mathematically convolving the phantom shapes with a 3D Gaussian point-spread function, and the results of the calculations were compared with the experimental data. The data show that the shape effect in PET tumor imaging can be as large as 15% for ellipsoid phantoms with axis ratios of 2:1, volume of 1.15 cm 3, and tumor-to-background activity concentration ratio of 9:1. This is explained by a greater loss of counts along the minor axis direction in the ellipsoid tumors compared to that of spheres of the same volume. The results of this PhD research confirm the existence of a tumor shape effect PET imaging. However, except in the case of ellipsoids with major-to-minor axis ratio greater than 2:1, a correction for the effect using recovery coefficients is expected to be challenging because its magnitude is comparable to the repeatability of the PET measurements.

Mille, Matthew M.

144

Molar Malocclusions in Pine Voles (Microtus pinetorum)  

PubMed Central

Here we describe 5 cases of molar malocclusions in adult pine voles (Microtus pinetorum) used for behavioral endocrinology studies. This species belongs to the subfamily Microtinae, which possess aradicular hypsodont molars. The abnormal molars identified caused apparent difficulty in mastication, resulting in poor body condition necessitating euthanasia. Postmortem examination of the oral cavity revealed grossly elongated mandibular and maxillary molars with abnormal wear at occlusal surfaces. This colony health problem was addressed successfully by adding autoclaved hardwood sticks to each cage as an enrichment tool. PMID:19653952

Harvey, Stephen B; Alworth, Leanne C; Blas-Machado, Uriel

2009-01-01

145

METHODS DEVELOPMENT FOR ASSESSING AIR POLLUTION CONTROL BENEFITS. VOLUME IV. STUDIES ON PARTIAL EQUILIBRIUM APPROACHES TO VALUATION OF ENVIRONMENTAL AMENITIES  

EPA Science Inventory

The research presented in this volume of a five volume study of the economic benefits of air pollution control explores various facets of the two central project objectives that have not been given adequate attention in the previous volumes. The valuations developed in these prev...

146

Enamel thickness of human maxillary molars reconsidered.  

PubMed

Forty-four modern human maxillary molars (M1 = 21, M2 = 12, and M3 = 11) were sectioned through the mesial cusps in a plane perpendicular to the cervical margin of the crown. Eight measurements of enamel thickness as well as bucco-lingual (BL) and mesio-distal (MD) diameters were recorded for each tooth in order to investigate differences in these dimensions between tooth categories. Uni- and multi-variate analyses revealed first maxillary molars to have generally thinner enamel than second or third upper molars, especially with regard to the occlusal basin. Furthermore, the decrease of MD diameters from anterior to posterior is greater than that of BL diameters. Principal Component Analysis using enamel thickness measurements resulted in complete separation of first molars, while second and third maxillary molars showed a certain amount of overlap. This finding casts doubt on using an overall measure of "molar enamel thickness" derived from mixed samples of molars for taxonomic purposes. There appears to be a relationship between bite force and enamel thickness such that posterior molars, where masticatory forces are stronger, have thicker enamel than anterior teeth. It is suggested that the gradient of enamel thickness between (and within) teeth in extant and extinct species may thus provide further information about relative wear resistance as well as the biomechanical constraints of the orofacial skeleton. PMID:8273831

Macho, G A; Berner, M E

1993-10-01

147

Intravenous sedation for third molar surgery.  

PubMed

The surgical removal of third molars is a frequently carried out procedure under day-stay general anesthesia. Economic considerations and the demand on hospital facilities together with the reduced incidence of morbidity suggest that intravenous sedation is an excellent alternative modality. Thirty cases of third molar surgery with intravenous sedation are described wherein excellent operating conditions and reduced morbidity are reported. PMID:8219933

Grainger, J K

1993-01-01

148

Antibiotics in third molar surgery.  

PubMed

The aim of this survey was to assess the knowledge and practice of Swiss dentists focusing on the use of antibiotics in prophylactic surgical removal of lower wisdom teeth. A postal survey was conducted among all 3288 dentists who are members of the Swiss Dental Society (SSO) representing nearly all dentists in Switzerland. The questionnaire consisted of 13 questions with mostly multiple-choice answers. Demographic profile, surgical experience, the use of antibiotics, and wound management, i.e. wound closure and the use of mouth rinse were assessed. A response rate of 55% was obtained. Most Swiss dentists perform surgical extractions in their practices. Of all dentists, 18.6% used antibiotics routinely, but a large variation was found comparing the three linguistic regions of Switzerland with the highest prescription rate of 48% in the French-speaking south-west of Switzerland. Fifty-two percent of dentists prescribed amoxicillin in a dose of 750 mg. Most often three daily doses were prescribed (47%). A postoperative regime was prescribed by 54.4% of dentists. French language (p=0.003), graduation from the university of Geneva (p=0.007), foreign diplomas (p<0.001), and dentists with diplomas awarded from 2001-2006 (p=0.004) showed a highly significant correlation with the use of antibiotics. In Switzerland, prophylactic antibiotics are used in third molar surgery. Antibiotic prescription however largely depends on geographical situation and dentist profiles. The assessment of antibiotic use in private practices is important in the light of growing evidence that antibiotic overuse may lead to development of multiresistant bacterial strains. In a second part results regarding wound management and mouth rinse will be presented. PMID:24671748

Vlcek, Daniel; Razavi, Amir; Kuttenberger, Johannes J

2014-01-01

149

Role of third molars in orthodontics.  

PubMed

The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too. PMID:25685759

Almpani, Konstantinia; Kolokitha, Olga-Elpis

2015-02-16

150

Role of third molars in orthodontics  

PubMed Central

The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too. PMID:25685759

Almpani, Konstantinia; Kolokitha, Olga-Elpis

2015-01-01

151

Unilateral Molar Distalization: A Nonextraction Therapy  

PubMed Central

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. PMID:23320203

Prasad, M. Bhanu; Sreevalli, S.

2012-01-01

152

Impact of dual-time-point 18 F-FDG PET imaging and partial volume correction in the assessment of solitary pulmonary nodules  

Microsoft Academic Search

Purpose  Our aim was to assess the diagnostic potential of 18F-FDG PET using partial volume correction and dual-time-point imaging in the assessment of solitary pulmonary nodules.\\u000a \\u000a \\u000a \\u000a Methods  We included 265 patients in this retrospective study (171 men; 94 women; age range, 41–92 years). All had pulmonary nodules\\u000a on CT, and diagnosis was confirmed by biopsy or follow-up CT. All underwent whole body FDG

Khaled Alkhawaldeh; Gonca Bural; Rakesh Kumar; Abass Alavi

2008-01-01

153

Molars and incisors: show your microarray IDs  

PubMed Central

Background One of the key questions in developmental biology is how, from a relatively small number of conserved signaling pathways, is it possible to generate organs displaying a wide range of shapes, tissue organization, and function. The dentition and its distinct specific tooth types represent a valuable system to address the issues of differential molecular signatures. To identify such signatures, we performed a comparative transcriptomic analysis of developing murine lower incisors, mandibular molars and maxillary molars at the developmental cap stage (E14.5). Results 231 genes were identified as being differentially expressed between mandibular incisors and molars, with a fold change higher than 2 and a false discovery rate lower than 0.1, whereas only 96 genes were discovered as being differentially expressed between mandibular and maxillary molars. Numerous genes belonging to specific signaling pathways (the Hedgehog, Notch, Wnt, FGF, TGF?/BMP, and retinoic acid pathways), and/or to the homeobox gene superfamily, were also uncovered when a less stringent fold change threshold was used. Differential expressions for 10 out of 12 (mandibular incisors versus molars) and 9 out of 10 selected genes were confirmed by quantitative reverse transcription-PCR (qRT-PCR). A bioinformatics tool (Ingenuity Pathway Analysis) used to analyze biological functions and pathways on the group of incisor versus molar differentially expressed genes revealed that 143 genes belonged to 9 networks with intermolecular connections. Networks with the highest significance scores were centered on the TNF/NF?B complex and the ERK1/2 kinases. Two networks ERK1/2 kinases and tretinoin were involved in differential molar morphogenesis. Conclusion These data allowed us to build several regulatory networks that may distinguish incisor versus molar identity, and may be useful for further investigations of these tooth-specific ontogenetic programs. These programs may be dysregulated in transgenic animal models and related human diseases leading to dental anomalies. PMID:23531410

2013-01-01

154

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage  

Microsoft Academic Search

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG

Gero S. M Kinzinger; Ulrike B Fritz; Franz-Günter Sander; Peter R Diedrich

2004-01-01

155

Randomized trial comparing partial versus complete chordal-sparing mitral valve replacement: Effects on left ventricular volume and function  

Microsoft Academic Search

Objective: The merits of retaining the subvalvular apparatus during mitral valve replacement for chronic mitral regurgitation have been demonstrated in numerous retrospective clinical investigations but not in a randomized study. In this report we analyzed the early and late effects of complete versus partial chordal preservation on left ventricular mechanics. Methods: Forty-seven patients undergoing isolated surgical correction of mitral insufficiency

Kwok L. Yun; Colleen F. Sintek; D. Craig Miller; Thomas A. Pfeffer; Gary S. Kochamba; Siavosh Khonsari; Michael R. Zile

2002-01-01

156

Randomized trial comparing partial versus complete chordal-sparing mitral valve replacement: Effects on left ventricular volume and function  

Microsoft Academic Search

Objective: The merits of retaining the subvalvular apparatus during mitral valve replacement for chronic mitral regurgitation have been demonstrated in numerous retrospective clinical investigations but not in a randomized study. In this report we analyzed the early and late effects of complete versus partial chordal preservation on left ventricular mechanics. Methods: Forty-seven patients undergoing isolated surgical correction of mitral insuf-

Kwok L. Yun; Colleen F. Sintek; D. Craig; Thomas A. Pfeffer; Gary S. Kochamba; Siavosh Khonsari; Michael R. Zile

157

Cholesterol-Induced Variations in the Volume and Enthalpy Fluctuations of Lipid Bilayers  

Microsoft Academic Search

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?xc?0.5). The temperature dependence of the sound velocity number, of the apparent specific partial volume of

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

1998-01-01

158

Orthodontic extrusion of horizontally impacted mandibular molars  

PubMed Central

Objective: To introduce and evaluate a novel approach in treating horizontally impacted mandibular second and third molars. Materials and methods: An orthodontic technique was applied for treatment of horizontally impacted mandibular second and third molars, which included a push-type spring for rotation first, and then a cantilever for extrusion. There were 8 mandibular third molars (M3s) and 2 second molars (M2s) in this study. Tooth mobility, extraction time, the inclination and parallelism of the impacted tooth, alveolar bone height of the adjacent tooth, and the relationship of impacted M3 and the inferior alveolar nerve (IAN) were evaluated. Results: Two horizontally impacted M2s could be upright in the arch and good occlusal relationships were obtained after treatment. All impacted M3s were successfully separated from the IAN, without any neurologic consequences. The average extraction time was 5 minutes. There was a significant change in the inclination and parallelism of the impacted tooth after treatment. A new bone apposition with the average height of 3.2 mm was noted distal to the adjacent tooth. Conclusions: This two-step orthodontic technique as presented here may be a safe and feasible alternative in management of severely horizontally impacted mandibular molars, which achieves a successful separation of M3s from the IAN and an excellent position for M2s. PMID:25419364

Ma, Zhigui; Yang, Chi; Zhang, Shanyong; Xie, Qianyang; Shen, Yuqing; Shen, Pei

2014-01-01

159

Microbial complexes detected in the second\\/third molar region in patients with asymptomatic third molars  

Microsoft Academic Search

Purpose: Our goal was to report the detection and levels of pathogenic bacteria in subgingival plaque samples taken from the distal of all second molars in 295 patients with asymptomatic third molars. Patients and Methods: Data assessing oral health were collected from each of these healthy patients (ASA Classes I and II). Probing depth (PD), at 6 sites per tooth,

Raymond P. White; Phoebus N. Madianos; Steven Offenbacher; Ceib Phillips; George H. Blakey; Richard H. Haug; Robert D. Marciani

2002-01-01

160

The root apices of the premolars and molars  

E-print Network

of the mandibular molar region does not show all of the specific region on the film. The third molar has been "cutFig. 8-1 The root apices of the premolars and molars are "cut off" because the film was placed too. Fig. A Illusion of a closed contact point between the second premolar and first molar due to incorrect

161

PET imaging of thin objects: measuring the effects of positron range and partial-volume averaging in the leag of Nicotiana Tabacum  

SciTech Connect

PET imaging in plants is receiving increased interest as a new strategy to measure plant responses to environmental stimuli and as a tool for phenotyping genetically engineered plants. PET imaging in plants, however, poses new challenges. In particular, the leaves of most plants are so thin that a large fraction of positrons emitted from PET isotopes ({sup 18}F, {sup 11}C, {sup 13}N) escape while even state-of-the-art PET cameras have significant partial-volume errors for such thin objects. Although these limitations are acknowledged by researchers, little data have been published on them. Here we measured the magnitude and distribution of escaping positrons from the leaf of Nicotiana tabacum for the radionuclides {sup 18}F, {sup 11}C and {sup 13}N using a commercial small-animal PET scanner. Imaging results were compared to radionuclide concentrations measured from dissection and counting and to a Monte Carlo simulation using GATE (Geant4 Application for Tomographic Emission). Simulated and experimentally determined escape fractions were consistent. The fractions of positrons (mean {+-} S.D.) escaping the leaf parenchyma were measured to be 59 {+-} 1.1%, 64 {+-} 4.4% and 67 {+-} 1.9% for {sup 18}F, {sup 11}C and {sup 13}N, respectively. Escape fractions were lower in thicker leaf areas like the midrib. Partial-volume averaging underestimated activity concentrations in the leaf blade by a factor of 10 to 15. The foregoing effects combine to yield PET images whose contrast does not reflect the actual activity concentrations. These errors can be largely corrected by integrating activity along the PET axis perpendicular to the leaf surface, including detection of escaped positrons, and calculating concentration using a measured leaf thickness.

Alexoff, D.L.; Alexoff, D.L.; Dewey, S.L.; Vaska, P.; Krishnamoorthy, S.; Ferrieri, R.; Schueller, M.; Schlyer, D.; Fowler, J.S.

2011-03-01

162

Alveolitis after operative removal of third molars in the mandible.  

PubMed

The aim of the investigation was to assess the importance of various factors in the aetiology of alveolitis sicca dolorosa. Two hundren partially erupted or totally impacted mandibular third molars were surgically removed. The patients were divided into four groups. The patients in group 1 were premedicated with a single dose of penicillin-V (phenoxymethylpenicillin), those in group 2 with an antisialogogue (methylscopolamine nitrate), and those in group 3 with an antifibrinolytic agent (tranexamic acid). Group 4 were non-premedicated controls. The frequency of alveolitis in the groups 1 and 2 was significantly less than in the groups 3 and 4. This indicates the importance of salivary contamination of the surgical field and of infection as aetiologic factors in alveolitis. PMID:6797972

Krekmanov, L

1981-06-01

163

The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation  

SciTech Connect

Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were not associated with late toxicity.

Leonard, Kara Lynne, E-mail: karalynne.kerr@gmail.com [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Hepel, Jaroslaw T. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Hiatt, Jessica R. [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)] [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Dipetrillo, Thomas A. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Price, Lori Lyn [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States)] [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States); Wazer, David E. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)

2013-03-01

164

Dependence of the volume characteristics and viscosity of solutions of methanol-octane-naphthalene on composition at 25°C  

NASA Astrophysics Data System (ADS)

The limiting solubility of naphthalene in a mixture of methanol-octane at 25°C is determined via isothermal saturation. The kinematic viscosity of a mixture of methanol-octane-naphthalene is measured at 25°C. Data on the density of triple mixtures of methanol-octane-naphthalene, used to calculate the partial and apparent molar volumes of naphthalene, are obtained with a high degree of accuracy. The obtained results are discussed in terms of the interactions that occur in solution.

Dyshin, A. A.; Eliseeva, O. V.; Kiselev, M. G.

2014-10-01

165

Periodontal pathology associated with asymptomatic third molars  

Microsoft Academic Search

Purpose: We report the prevalence of periodontal probing depth (PD) as a clinical measure of the extent of periodontitis associated with asymptomatic third molars at the initial examination in a cohort of patients enrolled in an institutional review board[ndash ]approved longitudinal clinical trial. Patients and Methods: Three hundred twenty-nine healthy patients were enrolled during a 30-month period. Full mouth periodontal

George H. Blakey; Robert D. Marciani; Richard H. Haug; Ceib Phillips; Steven Offenbacher; Tarunjeet Pabla; Raymond P. White

2002-01-01

166

Compromised first permanent molars: an orthodontic perspective.  

PubMed

The first permanent molar (FPM) is commonly subject to significant compromise which may arise due to caries or endodontic complication, or from developmental anomalies such as hypoplasia. Compromised teeth with questionable prognosis may result in short and long-term clinical dilemmas. This review article highlights the factors that require careful consideration when a compromised FPM is detected and the importance of timely FPM extraction. Several clinical cases are described in detail to discuss possible treatment options from the orthodontic perspective. PMID:20415906

Ong, D C-V; Bleakley, J E

2010-03-01

167

Molar Tooth Diversity, Disparity, and Ecology in Cenozoic Ungulate Radiations  

Microsoft Academic Search

A classic example of adaptive radiation is the diversification of Cenozoic ungulates into herbivore adaptive zones. Their taxonomic diversification has been associated with changes in molar tooth morphology. Analysis of molar crown types of the Artiodactyla, Perissodactyla, and archaic ungulates (\\

Jukka Jernvall; John P. Hunter; Mikael Fortelius

1996-01-01

168

Distal molar movement with Kloehn headgear: Is it stable?  

Microsoft Academic Search

The aim of this study was to evaluate intramaxillary molar movement after 8 months of cervical traction and posttreatment displacement 7 years later. The total molar displacements in relation to stable intraosseous reference points were compared with those observed in an untreated control group that also had intraosseous reference indicators inserted. During the headgear period, the type of molar displacement

Birte Melsen; Michel Dalstra

2003-01-01

169

MOLAR Meeting BarcelonaAprit 22-251997  

E-print Network

MOLAR Meeting BarcelonaAprit 22-251997 Liverpool University (Environmental Radioactivity Research winds transportair massesover the land surface. Fallout at MOLAR sitesin the UK, Maritime Europe-100Bq *t y-t. The objectiveof the measurementsbeingcarriedwithin the MOLAR prograrnmeis to strengthenthe

Short, Daniel

170

Enzyme Molar Fractions: A Powerful Tool for Understanding Enzyme Kinetics.  

ERIC Educational Resources Information Center

Deduces the relationship between reduced velocity and molar fractions for productive enzyme complexes; obtains the mathematical expression of molar fractions for an enzyme with two specific binding sites per molecule; and proposes a useful plot to follow the dependence of enzyme molar fractions with the concentration of one of its ligands. (JN)

Serra, Juan L.; And Others

1986-01-01

171

UK National Third Molar project: the initial report  

Microsoft Academic Search

The National Third Molar (NTM) project was set up to assess current clinical practice in the UK concerning the management of third molar teeth. Patients were recruited from both hospital and general dental practice. During the one month study period 9248 patients with 26 577 third molars were recruited. In this report we present the findings in the 8298 patients

S. F. Worrall; K. Riden; R. Haskell; A. M. Corrigan

1998-01-01

172

Inflammatory mediators and periodontitis in patients with asymptomatic third molars  

Microsoft Academic Search

Purpose: Our goal was to report the detection and levels of gingival crevicular fluid (GCF) inflammatory mediators, sampled at the mesial of 4 first molars and distal of 4 second molars, in 316 patients with asymptomatic third molars. Patients and Methods: Levels of GCF inflammatory mediators, interleukin (IL)-1[beta ] and prostaglandin (PG)E2, were determined and log transformed for each patient.

Raymond P. White; Steven Offenbacher; Ceib Phillips; Richard H. Haug; George H. Blakey; Robert D. Marciani

2002-01-01

173

4. New perspectives on chimpanzee and human molar crown development  

E-print Network

4. New perspectives on chimpanzee and human molar crown development T.M. SMITH Human Evolution 11794-4364 U.S.A. lawrence.martin@stonybrook.edu Keywords: molar development, incremental feature, crown samples of chimpanzee and human molars suggested similarities in crown formation time, which is surprising

Smith, Tanya M.

174

Impact of partial-volume effect correction on the predictive and prognostic value of baseline 18F-FDG PET images in esophageal cancer  

PubMed Central

The objectives of this study were to investigate the clinical impact of partial volume effects (PVE) correction on the predictive and prognostic value of metabolically active tumor volume (MATV) measurements on 18F-FDG PET baseline scan for therapy response and overall survival in esophageal cancer patients. Methods 50 patients with esophageal cancer treated with concomitant radio-chemotherapy between 2004 and 2008 were retrospectively considered. PET baseline scans were corrected for PVE with iterative deconvolution incorporating wavelet denoising. MATV delineation on both original and corrected images was carried out using the automatic Fuzzy Locally Adaptive Bayesian (FLAB) methodology. Several parameters were extracted considering the original and corrected images: maximum and peak SUV, mean SUV, MATV and TLG (TLG=MATV×mean SUV). The predictive value of each parameter with or without correction was investigated using Kruskal-Wallis tests and the prognostic value with Kaplan-Meier curves. Results Whereas PVE correction had significant quantitative impact on the absolute values of the investigated parameters, their clinical value within the clinical context of interest was not significantly modified. This was observed for both overall survival and response to therapy. The hierarchy between parameters was the same before and after correction. SUV measurements (max, peak, mean) had non-significant (p>0.05) predictive or prognostic value, whereas functional tumor related measurements (MATV, TLG) were significant (p<0.002) predictors of response and independent prognostic factors. Conclusions PVE correction does not improve the predictive and prognostic value of baseline PET image derived parameters in esophageal cancer patients. PMID:22213819

Hatt, Mathieu; Le Pogam, Adrien; Visvikis, Dimitris; Pradier, Olivier; Cheze Le Rest, Catherine

2012-01-01

175

A Prospective Pathologic Study to Define the Clinical Target Volume for Partial Breast Radiation Therapy in Women With Early Breast Cancer  

SciTech Connect

Purpose: To determine an appropriate clinical target volume for partial breast radiation therapy (PBRT) based on the spatial distribution of residual invasive and in situ carcinoma after wide local excision (WLE) for early breast cancer or ductal carcinoma in situ (DCIS). Methods and Materials: We performed a prospective pathologic study of women potentially eligible for PBRT who had re-excision and/or completion mastectomy after WLE for early breast cancer or DCIS. A pathologic assessment protocol was used to determine the maximum radial extension (MRE) of residual carcinoma from the margin of the initial surgical cavity. Women were stratified by the closest initial radial margin width: negative (>1 mm), close (>0 mm and {<=}1 mm), or involved. Results: The study population was composed of 133 women with a median age of 59 years (range, 27-82 years) and the following stage groups: 0 (13.5%), I (40.6%), II (38.3%), and III (7.5%). The histologic subtypes of the primary tumor were invasive ductal carcinoma (74.4%), invasive lobular carcinoma (12.0%), and DCIS alone (13.5%). Residual carcinoma was present in the re-excision and completion mastectomy specimens in 55.4%, 14.3%, and 7.2% of women with an involved, close, and negative margin, respectively. In the 77 women with a noninvolved radial margin, the MRE of residual disease, if present, was {<=}10 mm in 97.4% (95% confidence interval 91.6-99.5) of cases. Larger MRE measurements were significantly associated with an involved margin (P<.001), tumor size >30 mm (P=.03), premenopausal status (P=.03), and negative progesterone receptor status (P=.05). Conclusions: A clinical target volume margin of 10 mm would encompass microscopic residual disease in >90% of women potentially eligible for PBRT after WLE with noninvolved resection margins.

Nguyen, Brandon T., E-mail: Brandon.Nguyen@act.gov.au [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Canberra Hospital, Radiation Oncology Department, Garran, ACT (Australia); Deb, Siddhartha [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia) [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Victorian Cancer Biobank, Cancer Council of Victoria, Carlton, Victoria (Australia); Fox, Stephen [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)] [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Hill, Prudence [Department of Anatomical Pathology, St. Vincent's Hospital Melbourne, Fitzroy, Victoria (Australia)] [Department of Anatomical Pathology, St. Vincent's Hospital Melbourne, Fitzroy, Victoria (Australia); Collins, Marnie [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)] [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Chua, Boon H. [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia) [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); University of Melbourne, Parkville, Victoria (Australia)

2012-12-01

176

The influence of the ethanol-water molar ratio in the precursor solution on morphology and photocatalytic activity of pyrolytic ZnO films.  

PubMed

Zinc oxide films were fabricated by a homemade spray pyrolysis system equipped with an optical setup ensuring the in situ control of the film growth. Zinc acetate (0.1 M) diluted in a mixture of ethanol and water was used as the precursor solution. The ethanol-water molar ratio, gamma, in the precursor solution was varied from 0 to 0.92. The deposition temperature and the pH of the precursor solution were kept at 350 degrees C and 4.5, respectively. X-ray diffraction patterns revealed that films were zincitelike with a grain size depending on the ethanol-water molar ratio in the precursor solution. The interference pattern obtained during film deposition was used to monitor the film roughness; it was found that this is related with those results of surfaces and optical analysis obtained by scanning electron microscopy and spectrophotometric measurements, respectively. The morphology of the ZnO films obtained from gamma equal to either 0 or 0.92 are dense with agglomerates uniformly distributed, whereas the films obtained from gamma equal to either 0.03 or 0.06 are very rough with irregular agglomerates. The films obtained from gamma equal to 0.12, 0.18 and 0.31 are rough. Photoelectrocatalytic results indicated that there is a correlation of the partial molar volume of ethanol with respect to water in the spraying solution, with the photocatalytic efficiency of the ZnO films. We found that the maximum photodegradation of methyl orange in the solution occurs using ZnO films obtained with gamma = 0.12. PMID:15649109

Quintana, Maria; Rodríguez, Juan; Solis, José; Estrada, Walter

2005-01-01

177

Assessment of the severity of partial volume effects and the performance of two template-based correction methods in a SPECT/CT phantom experiment  

NASA Astrophysics Data System (ADS)

We investigated the severity of partial volume effects (PVE), which may occur in SPECT/CT studies, and the performance of two template-based correction techniques. A hybrid SPECT/CT system was used to scan a thorax phantom that included lungs, a heart insert and six cylindrical containers of different sizes and activity concentrations. This phantom configuration allowed us to have non-uniform background activity and a combination of spill-in and spill-out effects for several compartments. The reconstruction with corrections for attenuation, scatter and resolution loss but not PVE correction accurately recovered absolute activities in large organs. However, the activities inside segmented 17-120 mL containers were underestimated by 20%-40%. After applying our PVE correction to the data pertaining to six small containers, the accuracy of the recovered total activity improved with errors ranging between 3% and 22% (non-iterative method) and between 5% and 15% (method with an iteratively updated background activity). While the non-iterative template-based algorithm demonstrated slightly better accuracy for cases with less severe PVE than the iterative algorithm, it underperformed in situations with considerable spill out and/or mixture of spill-in and spill-out effects.

Shcherbinin, S.; Celler, A.

2011-08-01

178

Preemptive analgesia in third molar impaction surgery  

PubMed Central

Introduction: We have evaluated efficacy of diclofenac sodium as pre-emptive analgesia agent in a prospective triple blind placebo controlled randomized clinical trial in a patients undergoing third molar impaction surgery. Materials and Methods: Randomization of groups was done by randomization software and two groups were constituted one group receiving placebo pre operatively and then the drug for next five days while the other group was given diclofenac sodium pre operatively and then for five days. Results: Results were achieved with help of measurement of outcome variables like postoperative tenderness, swelling and trismus on a visual analogous scale (VAS) and other personalized scale. Collected data shows that there is a significant reduction in the score of postop tenderness in experimental group (P = 0.00), while there is a minimal difference between score of postoperative swelling and tenderness (P > 0.04). Conclusion: So, we can conclude that use of diclofenac sodium as a preemptive analgesic agent is beneficial for better pain control in third molar impaction surgery. PMID:23833488

Shah, Rakesh; Mahajan, Amit; Shah, Navin; Dadhania, Ashish P.

2012-01-01

179

Clinical significance of computed tomography assessment for third molar surgery  

PubMed Central

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

Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

2014-01-01

180

Impact of partial volume effect correction on cerebral ?-amyloid imaging in APP-Swe mice using [(18)F]-florbetaben PET.  

PubMed

We previously investigated the progression of ?-amyloid deposition in brain of mice over-expressing amyloid-precursor protein (APP-Swe), a model of Alzheimer's disease (AD), in a longitudinal PET study with the novel ?-amyloid tracer [(18)F]-florbetaben. There were certain discrepancies between PET and autoradiographic findings, which seemed to arise from partial volume effects (PVE). Since this phenomenon can lead to bias, most especially in the quantitation of brain microPET studies of mice, we aimed in the present study to investigate the magnitude of PVE on [(18)F]-florbetaben quantitation in murine brain, and to establish and validate a useful correction method (PVEC). Phantom studies with solutions of known radioactivity concentration were performed to measure the full-width-at-half-maximum (FWHM) resolution of the Siemens Inveon DPET and to validate a volume-of-interest (VOI)-based PVEC algorithm. Several VOI-brain-masks were applied to perform in vivo PVEC on [(18)F]-florbetaben data from C57BL/6(N=6) mice, while uncorrected and PVE-corrected data were cross-validated with gamma counting and autoradiography. Next, PVEC was performed on longitudinal PET data set consisting of 43 PET scans in APP-Swe (13-20months) and age-matched wild-type (WT) mice using the previously defined masks. VOI-based cortex-to-cerebellum ratios (SUVR) were compared for uncorrected and PVE-corrected results. Brains from a subset of transgenic mice were ultimately examined by autoradiography ex vivo and histochemistry in vitro as gold standard assessments, and compared to VOI-based PET results. The phantom study indicated a FWHM of 1.72mm. Applying a VOI-brain-mask including extracerebral regions gave robust PVEC, with increased precision of the SUVR results. Cortical SUVR increased with age in APP-Swe mice compared to baseline measurements (16months: +5.5%, p<0.005; 20months: +15.5%, p<0.05) with uncorrected data, and to a substantially greater extent with PVEC (16months: +12.2% p<0.005; 20months: +36.4% p<0.05). WT animals showed no binding changes, irrespective of PVEC. Relative to autoradiographic results, the error [%] for uncorrected cortical SUVR was 18.9% for native PET data, and declined to 4.8% upon PVEC, in high correlation with histochemistry results. We calculate that PVEC increases by 10% statistical power for detecting altered [(18)F]-florbetaben uptake in aging APP-Swe mice in planned studies of disease modifying treatments on amyloidogenesis. PMID:24055703

Brendel, Matthias; Delker, Andreas; Rötzer, Christina; Böning, Guido; Carlsen, Janette; Cyran, Clemens; Mille, Erik; Gildehaus, Franz Josef; Cumming, Paul; Baumann, Karlheinz; Steiner, Harald; Haass, Christian; Herms, Jochen; Bartenstein, Peter; Rominger, Axel

2014-01-01

181

Improved longitudinal [(18)F]-AV45 amyloid PET by white matter reference and VOI-based partial volume effect correction.  

PubMed

Amyloid positron-emission-tomography (PET) offers an important research and diagnostic tool for investigating Alzheimer's disease (AD). The majority of amyloid PET studies have used the cerebellum as a reference region, and clinical studies have not accounted for atrophy-based partial volume effects (PVE). Longitudinal studies using cerebellum as reference tissue have revealed only small mean increases and high inter-subject variability in amyloid binding. We aimed to test the effects of different reference regions and PVE-correction (PVEC) on the discriminatory power and longitudinal performance of amyloid PET. We analyzed [(18)F]-AV45 PET and T1-weighted MRI data of 962 subjects at baseline and two-year follow-up data of 258 subjects. Cortical composite volume-of-interest (VOI) values (COMP) for tracer uptake were generated using either full brain atlas VOIs, gray matter segmented VOIs or gray matter segmented VOIs after VOI-based PVEC. Standard-uptake-value ratios (SUVR) were calculated by scaling the COMP values to uptake in cerebellum (SUVRCBL), brainstem (SUVRBST) or white matter (SUVRWM). Mean SUV, SUVR, and changes after PVEC were compared at baseline between diagnostic groups of healthy controls (HC; N=316), mild cognitive impairment (MCI; N=483) and AD (N=163). Receiver operating characteristics (ROC) were calculated for the discriminations between HC, MCI and AD, and expressed as area under the curve (AUC). Finally, the longitudinal [(18)F]-AV45-PET data were used to analyze the impact of quantitation procedures on apparent changes in amyloid load over time. Reference region SUV was most constant between diagnosis groups for the white matter. PVEC led to decreases of COMP-SUV in HC (-18%) and MCI (-10%), but increases in AD (+7%). Highest AUCs were found when using PVEC with white matter scaling for the contrast between HC/AD (0.907) or with brainstem scaling for the contrast between HC/MCI (0.658). Longitudinal increases were greatest in all diagnosis groups with application of PVEC, and inter-subject variability was lowest for the white matter reference. Thus, discriminatory power of [(18)F]-AV45-PET was improved by use of a VOI-based PVEC and white matter or brainstem rather than cerebellum reference region. Detection of longitudinal amyloid increases was optimized with PVEC and white matter reference tissue. PMID:25482269

Brendel, Matthias; Högenauer, Marcus; Delker, Andreas; Sauerbeck, Julia; Bartenstein, Peter; Seibyl, John; Rominger, Axel

2015-03-01

182

Molar extinction coefficients of some fatty acids  

NASA Astrophysics Data System (ADS)

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.

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

2002-10-01

183

Statistical Interpretation of Femto-Molar Detection  

E-print Network

Over the last decade, many experiments have demonstrated that nanobiosensors based on Nanotubes and Nanowires are significantly more sensitive compared to their planar counterparts. Yet, there has been persistent gap between reports of analyte detection at ~femto-Molar concentration and theory suggesting the impossibility of sub-pM detection at the corresponding incubation time. This divide has persisted despite the sophistication of the theoretical models. In this paper, we calculate the statistics of diffusion-limited arrival-time distribution by a Monte Carlo method to suggest a statistical resolution of the enduring puzzle: The incubation time in the theory is the mean incubation time, while experiments suggest device stability limited the minimum incubation time. The difference in incubation times - both described by characteristic power-laws - provides an intuitive explanation of different detection limits anticipated by theory and experiments. These power laws broaden the scope of problems amenable to ...

Go, Jonghyun

2009-01-01

184

The unerupted maxillary second molar, due to an overlying and malformed upper third molar: treatment and follow-up.  

PubMed

This retrospective study presents the treatment and follow-up of 20 young patients with 23 impacted upper second molars, due to overlying, impacted upper third molars. The third molars were removed surgically under local anaesthesia. After removal of these palatally obstructing teeth, radiographic and clinical follow-up was performed. The purpose of this study was to evaluate the eruption progress of the upper second molars after surgery. Radiological and/or clinical follow-up showed complete eruption of 19 (83%) of the upper second molars. For those cases treated before the age of 12 years and 4 months (the mean eruption age), all the upper second molars erupted completely. For those cases where surgical removal was undertaken after the mean eruption age, four (17%) of the upper second molars did not completely erupt. It was concluded that early treatment of impacted upper second molars, due to overlying third molars, may lead to more rapid eruption. Further prospective research is necessary to develop guidelines for the removal of palatally obstructing third molars to avoid eruption problems. PMID:18287391

Salentijn, E G; Ras, F; Mensink, G; van Merkesteyn, J P R

2008-03-01

185

Third molar evaluation with cone-beam computerized tomography  

Microsoft Academic Search

Precise 3-dimensional localization of impacted mandibular third molars relative to the inferior dental canal (IDC) is critical to clinical management and surgical outcomes. Recently introduced dental 3-D volumetric imaging systems coupled with semi-automatic modeling techniques allows 3-D visualization of the IDC and the third-molar. Six impacted third molar sites were imaged with various 3-D volumetric imaging systems (NewTom 9000, Morita

Reyes Enciso; Robert A. Danforth; Emanuel S. Alexandroni; Ahmed Memon; James Mah

2006-01-01

186

Second molar impaction associated with lip bumper therapy  

PubMed Central

INTRODUCTION: Although lip bumpers (LBs) provide significant clinical gain of mandibular arch perimeter in mixed-dentition patients, orthodontists are reluctant to use them due to the possibility of permanent second molar eruptive disturbances. OBJECTIVE: The present study was conducted to assess second molar impaction associated with the use of LBs, and to investigate how they can be solved. MATERIAL AND METHODS: Lateral and panoramic radiographs of 67 patients (34 females and 33 males) were assessed prior (T1) and post-LB treatment (T2). LB therapy lasted for approximately 1.8 ± 0.9 years. Concomitant rapid palatal expansion (RPE) was performed in the maxilla at LB treatment onset. Impaction of mandibular second molars was assessed by means of panoramic radiographs in relation to the position of first mandibular molars. Horizontal and vertical movements of first and second molars were assessed cephalometrically on lateral cephalometric radiographs based on mandibular superimpositions. RESULTS: Eight (11.9%) patients had impacted second molars at the end of LB therapy. Two patients required surgical correction, whereas five required spacers and one patient was self-corrected. Mandibular first molar tip and apex migrated forward 1.3 mm and 2.3 mm, respectively. Second molar tip showed no statistically significant horizontal movement. CONCLUSION: Although LB therapy increased the risk of second molar impaction, impactions were, in most instances, easily solved. PMID:25628086

Jacob, Helder Baldi; LeMert, Shawn; Alexander, Richard G.; Buschang, Peter H.

2014-01-01

187

Influence of the partial volume correction method on 18F-fluorodeoxyglucose brain kinetic modelling from dynamic PET images reconstructed with resolution model based OSEM  

NASA Astrophysics Data System (ADS)

Kinetic parameters estimated from dynamic 18F-fluorodeoxyglucose (18F-FDG) PET acquisitions have been used frequently to assess brain function in humans. Neglecting partial volume correction (PVC) for a dynamic series has been shown to produce significant bias in model estimates. Accurate PVC requires a space-variant model describing the reconstructed image spatial point spread function (PSF) that accounts for resolution limitations, including non-uniformities across the field of view due to the parallax effect. For ordered subsets expectation maximization (OSEM), image resolution convergence is local and influenced significantly by the number of iterations, the count density, and background-to-target ratio. As both count density and background-to-target values for a brain structure can change during a dynamic scan, the local image resolution may also concurrently vary. When PVC is applied post-reconstruction the kinetic parameter estimates may be biased when neglecting the frame-dependent resolution. We explored the influence of the PVC method and implementation on kinetic parameters estimated by fitting 18F-FDG dynamic data acquired on a dedicated brain PET scanner and reconstructed with and without PSF modelling in the OSEM algorithm. The performance of several PVC algorithms was quantified with a phantom experiment, an anthropomorphic Monte Carlo simulation, and a patient scan. Using the last frame reconstructed image only for regional spread function (RSF) generation, as opposed to computing RSFs for each frame independently, and applying perturbation geometric transfer matrix PVC with PSF based OSEM produced the lowest magnitude bias kinetic parameter estimates in most instances, although at the cost of increased noise compared to the PVC methods utilizing conventional OSEM. Use of the last frame RSFs for PVC with no PSF modelling in the OSEM algorithm produced the lowest bias in cerebral metabolic rate of glucose estimates, although by less than 5% in most cases compared to the other PVC methods. The results indicate that the PVC implementation and choice of PSF modelling in the reconstruction can significantly impact model parameters.

Bowen, Spencer L.; Byars, Larry G.; Michel, Christian J.; Chonde, Daniel B.; Catana, Ciprian

2013-10-01

188

SU-E-J-76: Incorporation of Ultrasound Elastography in Target Volume Delineation for Partial Breast Radiotherapy Planning: A Comparative Study  

SciTech Connect

Purpose: There is substantial observer variability in the delineation of target volumes for post-surgical partial breast radiotherapy because the tumour bed has poor x-ray contrast. This variability may result in substantial variations in planned dose distribution. Ultrasound elastography (USE) has an ability to detect mechanical discontinuities and therefore, the potential to image the scar and distortion in breast tissue architecture. The goal of this study was to compare USE techniques: strain elastography (SE), shear wave elastography (SWE) and acoustic radiation force impulse (ARFI) imaging using phantoms that simulate features of the tumour bed, for the purpose of incorporating USE in breast radiotherapy planning. Methods: Three gelatine-based phantoms (10% w/v) containing: a stiff inclusion (gelatine 16% w/v) with adhered boundaries, a stiff inclusion (gelatine 16% w/v) with mobile boundaries and fluid cavity inclusion (to mimic seroma), were constructed and used to investigate the USE techniques. The accuracy of the elastography techniques was quantified by comparing the imaged inclusion with the modelled ground-truth using the Dice similarity coefficient (DSC). For two regions of interest (ROI), the DSC measures their spatial overlap. Ground-truth ROIs were modelled using geometrical measurements from B-mode images. Results: The phantoms simulating stiff scar tissue with adhered and mobile boundaries and seroma were successfully developed and imaged using SE and SWE. The edges of the stiff inclusions were more clearly visible in SE than in SWE. Subsequently, for all these phantoms the measured DSCs were found to be higher for SE (DSCs: 0.91–0.97) than SWE (DSCs: 0.68–0.79) with an average relative difference of 23%. In the case of seroma phantom, DSC values for SE and SWE were similar. Conclusion: This study presents a first attempt to identify the most suitable elastography technique for use in breast radiotherapy planning. Further analysis will include comparison of ARFI with SE and SWE. This work is supported by the EPSRC Platform Grant, reference number EP/H046526/1.

Juneja, P; Harris, E; Bamber, J [The Institute of Cancer Research, London (United Kingdom); Royal Marsden NHS Foundation Trust, London (United Kingdom)

2014-06-01

189

Estimation of input functions from dynamic [18F]FLT PET studies of the head and neck with correction for partial volume effects  

PubMed Central

Background We present a method for extracting arterial input functions from dynamic [18F]FLT PET images of the head and neck, directly accounting for the partial volume effect. The method uses two blood samples, for which the optimum collection times are assessed. Methods Six datasets comprising dynamic PET images, co-registered computed tomography (CT) scans and blood-sampled input functions were collected from four patients with head and neck tumours. In each PET image set, a region was identified that comprised the carotid artery (outlined on CT images) and surrounding tissue within the voxels containing the artery. The time course of activity in the region was modelled as the sum of the blood-sampled input function and a compartmental model of tracer uptake in the surrounding tissue. The time course of arterial activity was described by a mathematical function with seven parameters. The parameters of the function and the compartmental model were simultaneously estimated, aiming to achieve the best match between the modelled and imaged time course of regional activity and the best match of the estimated blood activity to between 0 and 3 samples. The normalised root-mean-square (RMSnorm) differences and errors in areas under the curves (AUCs) between the measured and estimated input functions were assessed. Results A one-compartment model of tracer movement to and from the artery best described uptake in the tissue surrounding the artery, so the final model of the input function and tissue kinetics has nine parameters to be estimated. The estimated and blood-sampled input functions agreed well when two blood samples, obtained at times between 2 and 8 min and between 8 and 60 min, were used in the estimation process (RMSnorm values of 1.1 ± 0.5 and AUC errors for the peak and tail region of the curves of 15% ± 9% and 10% ± 8%, respectively). A third blood sample did not significantly improve the accuracy of the estimated input functions. Conclusions Input functions for FLT-PET studies of the head and neck can be estimated well using a one-compartment model of tracer movement and TWO blood samples obtained after the peak in arterial activity. PMID:24369816

2013-01-01

190

Sensory nerve impairment following mandibular third molar surgery  

Microsoft Academic Search

Purpose: This prospective study reports the rate and factors influencing sensory impairment of the inferior alveolar and lingual nerves after the removal of impacted mandibular third molars under local anesthesia. Patients and Methods: There were 741 patients with 741 mandibular third molars removed under local anesthesia during a 3-year period from 1994 to 1997. Standardized data collection included the patient's

Anwar B Bataineh

2001-01-01

191

Immediate and late mandibular fractures after third molar removal  

Microsoft Academic Search

Purpose: In this retrospective study, we analyzed immediate and late mandibular fractures after impacted lower third molar surgery. Patients and Methods: One hundred fifty oral and maxillofacial surgeons in the north of- France were questioned about their experience with intraoperative and late mandibular fracture after third molar surgery. Cases were examined clinically and radiographically. Results: Thirty-seven fractures were reported in

Philippe Libersa; David Roze; Thierry Cachart; Jean-Claude Libersa

2002-01-01

192

Fusion of complex odontome with permanent mandibular molar.  

PubMed

Odontomas are malformation of the dental tissue, arising during normal tooth development. They are usually asymptomatic, but often associated with tooth eruption disturbance. This article reports a case of complex odontome in a 23-year-male, which hampered the eruption of mandibular right second molar as well devitalization of first molar. PMID:23066237

Talari, Bharathi H; Ananda, Divya; Prince, Christo N; Annaporna, Chandrakala S; Pranavadhyani

2012-08-01

193

An Epidemiologic Study of Deciduous Molar Relations in Preschool Children  

Microsoft Academic Search

This study indicated that distoclusion decreased significantly with age and was more prevalent in siblings of children with Class II molar relation as compared with the prevalence for the total population. Children of middle socioeconomic status (SES) and girls with Class I molar relation had prevalences of posterior crossbite significantly greater than lower SES children and boys, respectively. Finger habits

Peter F. Infante

1975-01-01

194

PULPOTOMIES WITH PORTLAND CEMENT IN HUMAN PRIMARY MOLARS  

PubMed Central

Two clinical cases in which Portland cement (PC) was applied as a medicament after pulpotomy of mandibular primary molars in children are presented. Pulpotomy using PC was carried out in two mandibular first molars and one mandibular second molar, which were further followed-up. At the 3, 6 and 12-month follow-up appointments, clinical and radiographic examinations of the pulpotomized teeth and their periradicular area revealed that the treatments were successful in maintaining the teeth asymptomatic and preserving pulpal vitality. Additionally, the formation of a dentin bridge immediately below the PC could be observed in the three molars treated. PC may be considered as an effective alternative for primary molar pulpotomies, at least in a short-term period. Randomized clinical trials with human teeth are required in order to determine the suitability of PC before unlimited clinical use can be recommended. PMID:19148409

Conti, Taísa Regina; Sakai, Vivien Thiemy; Fornetti, Ana Paula Camolese; Moretti, Ana Beatriz Silveira; Oliveira, Thais Marchini; Lourenço, Natalino; Machado, Maria Aparecida Andrade Moreira; Abdo, Ruy Cesar Camargo

2009-01-01

195

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes  

PubMed Central

Aims Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Material and methods Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 ?m. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. Results The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Conclusions Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well. PMID:25208969

2014-01-01

196

Excess molar volumes of ternary mixtures of [x{sub 1}CH{sub 3}CH{sub 2}COOCH{sub 2}CH{sub 3} + x{sub 2}CH{sub 3}(CH{sub 2}){sub 4}CH{sub 3} + (1 {minus} x{sub 1} {minus} x{sub 2})CH{sub 3}(CH{sub 2}){sub 6}OH or CH{sub 3}(CH{sub 2}){sub 7}OH] at the temperature of 298.15 K  

SciTech Connect

Excess molar volumes at the temperature 298.15 K were measured for the ternary systems [x{sub 1}ethyl propanoate + x{sub 2}hexane + (1 {minus} x{sub 1} {minus} x{sub 2})heptan-1-ol or (1 {minus} x{sub 1} {minus} x{sub 2})octan-1-ol] and for binary mixtures [x{sub 1}ethyl propanoate + (1 {minus} x{sub 1})n-hexane], [x{sub 1}ethyl propanoate + (1 {minus} x{sub 1})heptan-1-ol], [x{sub 1}n-hexane + (1 {minus} x{sub 1})heptan-1-ol], [x{sub 1}ethyl propanoate + (1 {minus} x{sub 1})octan-1-ol], and [x{sub 1}n-hexane + (1 {minus} x{sub 1})octan-1-ol]. Excess molar volumes were determined using a densimeter Anton Paar DMA 60/602. The experimental values were compared with the results obtained with some empirical methods for the estimation of ternary properties from binary results.

Jimenez, E.; Franjo, C.; Segade, L. [Univ. da Coruna (Spain)] [Univ. da Coruna (Spain); Legido, J.L. [Univ. de Vigo (Spain)] [Univ. de Vigo (Spain); Paz Andrade, M.I. [Univ. de Santiago (Spain)] [Univ. de Santiago (Spain)

1997-03-01

197

Oxygen stoichiometry, unit cell volume, and thermodynamic quantities of perovskite-type oxides  

Microsoft Academic Search

Perovskite-type oxides $${\\\\text{A}}_{{{\\\\text{1 - }}a}} {\\\\text{A}}^{\\\\prime }_{{\\\\text{a}}} {\\\\text{B}}_{{{\\\\text{1 - }}b}} {\\\\text{B}}^{\\\\prime }_{{\\\\text{b}}} {\\\\text{O}}_{{{\\\\text{3 - }}x}}$$ with A, A?=La, Ba, Sr; B, B?=Mn, Fe, Co were investigated by means of thermal analysis, solid electrolyte cells, and X-ray\\u000a diffraction. Partial molar thermodynamic quantities are determined and their relations with O\\/M stoichiometry, unit cell volume,\\u000a and phase stability were studied. The absolute values

Egle Girdauskaite; Helmut Ullmann; Mahmoud Al Daroukh; Vladimir Vashook; Martin Bülow; Ulrich Guth

2007-01-01

198

Molar heat capacity and entropy of calcium metal  

USGS Publications Warehouse

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.

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

1997-01-01

199

Revascularization/Regeneration performed in immature molars: case reports.  

PubMed

These 3 case reports the outcome of revascularization treatment in necrotic immature molars. During treatment, a tri antibiotic mix was used to disinfect the pulp for 2 weeks. Then a blood clot was created in the canal, over which mineral trioxide aggregate was placed. After 24 months, the immature molars showed continuation of root development. The patients were asymptomatic, no sinus tracts were evident and apical periodontitis was resolved Results from these cases show that revascularization/regeneration using 3Mix-MP method could be effective for managing immature permanent molar teeth with pulpal necrosis. PMID:23855165

Sönmez, I S; Akbay Oba, A; Erkmen Almaz, M

2013-01-01

200

Lingual Guttering Technique for Removal of Impacted Mandibular Third Molars  

PubMed Central

Background: To assess the clinical feasibility of lingual bone guttering technique for surgical extraction of mandibular third molars. Materials and Methods: 20 patients with thick lingual cortical plate were included in the study. Surgical extraction of mandibular third molars by lingual bone guttering technique was performed in all the subjects. These subjects were evaluated for integrity of lingual cortical plate and sensation of lingual nerve postoperatively. Results: All extractions done by lingual bone guttering technique were clinically feasible to perform and no complications were seen. Conclusion: Lingual bone guttering technique can be used safely in extraction of mandibular third molars with thick lingual cortical plate. PMID:25214725

Kale, Tejraj P; Pandit, Vikram S; Patil, Shankargouda; Pawar, Vivek; Shetty, Nisha

2014-01-01

201

Functional Patterns of Molar Occlusion in Platyrrhine Primates  

E-print Network

mechanics . Dentition Molars . Occlusion Tooth wear Platyrrhine. ABSTRACT Mechanico-functional features the particular kinds of insects fed upon by the different genera and the de- tailed characters of the dentition

Rosenberger, Alfred H.

202

Determining Molar Combining Ratios Using Radioisotopes--A Student Experiment  

ERIC Educational Resources Information Center

Outlines an experimental procedure in which an iodine radioisotope is used to determine molar combining ratios of lead and silver with the iodine. Tables and graphs show the definitive results that should be attainable. (CP)

Sears, Jerry A.

1976-01-01

203

Influence of molar ratios on properties of magnesium oxychloride cement  

SciTech Connect

A parametric study has been conducted to investigate the influences of the molar ratios of MgO/MgCl{sub 2} and H{sub 2}O/MgCl{sub 2} on the properties of magnesium oxychloride (MOC) cement. By an integrated assessment of the experimental studies of strength development and X-ray diffractograms, together with application of the relevant phase diagram, it is recognized that the molar ratios of MgO/MgCl{sub 2} and H{sub 2}O/MgCl{sub 2} can significantly affect the properties of MOC cement. For a MOC cement paste possessing a dominance of 5MgO.MgCl{sub 2}.8H{sub 2}O (phase 5) crystals, the molar ratios of MgO/MgCl{sub 2} of 11-17 and H{sub 2}O/MgCl{sub 2} of 12-18 are found to be the most favorite ranges for design purpose. The choose of the molar ratio of H{sub 2}O/MgCl{sub 2} is, however, largely depends on the molar ratio of MgO/MgCl{sub 2} mainly for controlling workability of paste. Therefore, the most critical parameter to be selected in the design process is the molar ratio of MgO/MgCl{sub 2}, although the reactivity of the MgO powder is also important. Besides, the molar ratio can also be affected by the reactivity of the MgO powder to be employed. It is believed that a molar ratio of MgO/MgCl{sub 2} of 13, the most suitable one shown in this study, can be used as a starting point in the normal practice.

Li Zongjin [Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong (China)]. E-mail: zongjin@ust.hk; Chau, C.K. [Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong (China)

2007-06-15

204

Patients' perception of recovery after third molar surgery  

Microsoft Academic Search

Purpose: This study evaluated patients' perceptions of recovery after third molar surgery.Methods: Two hundred forty-nine patients (age 13 to 37 years) at 2 clinical centers were enrolled in a prospective study before the surgical removal of third molars. Each patient was given a 21-item Health-Related Quality of Life instrument (HRQOL) to be completed each postoperative day (POD) for 14 days.

Shawn M Conrad; George H Blakey; Daniel A Shugars; Robert D Marciani; Ceib Phillips; Raymond P White

1999-01-01

205

Preliminary Evaluation of Sodium Hypochlorite for Pulpotomies in Primary Molars  

Microsoft Academic Search

Purpose: The purpose of this study was to compare the effectiveness of 5% sodium hypo- chlorite (NaOCl) to that of ferric sulfate (FeSO4) as a pulpotomy medicament in decayed primary molars. Methods: Healthy subjects between 4 and 9 years with at least 2 primary molars need- ing pulpotomy consented to receive either NaOCl or FeSO4 and restoration with IRM base\\/stainless

Kaaren G. Vargas; Brett Packham; David Lowman

2006-01-01

206

Diploid karyotype partial mole coexisting with live term fetus--case report and review of the world literature.  

PubMed

A partial molar pregnancy of diploid karyotype coexisting with live term fetus is a rare entity Most instances of partial mole are triploid and only a few eases of diploid partial moles with term delivery have been reported. Here, we report a case of partial mole concomitant with a 37-week live fetus. Postpartum karyotype of the placenta and the fetus revealed both as 46XX. Histological examination of the placenta showed a partial hydatidiform mole. We discuss the diagnosis based on presenting clinical picture and proper management of signs and symptoms of partial molar pregnancy coexisting with live term fetus and diploid karyotype, coupled with a review of the literature. PMID:23383567

Sak, Muhammet Erdal; Soydinc, Hatice Ender; Evsen, Mehmet Siddik; Sak, Sibel; Firat, U?ur

2012-10-01

207

Root canal morphology of South Asian Indian maxillary molar teeth  

PubMed Central

Objective: The objective was to study the root canal morphology of South Asian Indian Maxillary molars using a tooth clearing technique. Materials and Methods: Hundred teeth each comprising of first, second, and third molars collected from different dental schools and clinics in India were subjected to standard dye penetration, decalcification and clearing procedure before being studied. Results: The first molar mesiobuccal roots exhibited 69% Type I, 24% Type II, 4% Type IV, 2% Type V, and 1% exhibited a Vertuccis Type VIII canal anatomy. In the group with three separate roots the second molar mesiobuccal roots in exhibited 80.6% Type I, 15.3% Type II, 2.7% Type IV, and 1.4% Type V canal anatomy while the third molars mesiobuccal roots exhibited 57.4% Type I, 32% Type II, 2.1% Type III, 8.5% Type IV, 1% had a Type V canal anatomy in the similar group. Conclusion: A varied root canal anatomy was seen in the mesiobuccal root canal of the maxillary molars. PMID:25713497

Singh, Shishir; Pawar, Mansing

2015-01-01

208

Prevalence of Taurodont molars in a North Indian population  

PubMed Central

Background: It is very important for dentists to be familiar with anomalies of teeth not only for the clinical complications but also their management. Taurodontism also provides a valuable clue in detecting its association with various syndromes and other systemic conditions. The purpose of this study was to assess the prevalence of Taurodont molars among a North Indian population. Materials and Methods: A total of 1000 patients’ full-mouth periapical radiographs were screened. The radiographs were evaluated under optimal conditions using double magnifying glasses. A total of 7615 molars (including third molars) were evaluated. The relative incidence and the correlations regarding the location of Taurodont teeth (right versus left side and maxillary versus mandibular) were analyzed using the Chi-square test. Results: Twenty-eight patients were found to have a Taurodont molar (11 women and 17 men [P = 0.250]). The prevalence of Taurodont molar was 2.8%. Males had a higher prevalence rate than females (3.4% vs. 2.2%, respectively). A cluster analysis of total Taurodonts in the mandible (45%) versus maxilla (55%) of both males and females combined showed a statistically significant difference (P < 0.05). Conclusion: The occurrence of Taurodontism is basically based on racial expression in different populations. These variations in prevalence between different populations may be due to ethnic variations. The occurrence of Taurodont molars among this Indian population was rare.

Bharti, Ramesh; Chandra, Anil; Tikku, Aseem Prakash; Arya, Deeksha

2015-01-01

209

Finite Element Reconstruction of a Mandibular First Molar  

PubMed Central

Introduction Mandibular first molar is the most important tooth with complicated morphology. In finite element (FE) studies, investigators usually prefer to model anterior teeth with a simple and single straight root; it makes the results deviate from the actual case. The most complicated and time-consuming step in FE studies is modeling of the desired tooth, thus this study was performed to establish a finite element method (FEM) of reconstructing a mandibular first molar with the greatest precision. Materials and Methods An extracted mandibular first molar was digitized, and then radiographed from different aspects to achieve its outer and inner morphology. The solid model of tooth and root canals were constructed according to this data as well as the anatomy of mandibular first molar described in the literature. Result A three-dimensional model of mandibular first molar was created, giving special consideration to shape and root canal system dimensions. Conclusion This model may constitute a basis for investigating the effect of different clinical situations on mandibular first molars in vitro, especially on its root canal system. The method described here seems feasible and reasonably precise foundation for investigations. PMID:23717327

Ehsani, Sara; Mirhashemi, Fatemeh Sadat; Asgary, Saeed

2013-01-01

210

Genetic integration of molar cusp size variation in baboons  

PubMed Central

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 our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the non-occluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. PMID:20034010

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

2010-01-01

211

Emergence of the deciduous canines and molars in CLP children.  

PubMed

The emergence of the deciduous canines and molars was investigated as part of a longitudinal study into the emergence of the deciduous dentition in Dutch cleft lip and/or palate children (CLP) (Kramer et al., 1989). The study comprised a group of 71 CLP children and 74 normal children that served as a control. Mean emergence ages of the deciduous upper and lower canines and molars were studied. Emergence of the deciduous primary molar on the cleft side was delayed 2 months in the upper jaw and 1 month in the lower jaw in children with an unilateral cleft lip and palate. The deciduous primary molar on the non-cleft side was not delayed as compared with normal children. Local anatomical relationships could be a possible explanation for these findings. The deciduous canines and secondary molars in both jaws showed no significant differences in mean emergence ages as compared with the control group, nor between the different cleft types. No sex differences were found in any of the groups. A table is presented containing the mean emergence ages of all the teeth of the deciduous dentition for the various CLP-groups, divided in cleft and non-cleft side, and the control group. PMID:8436198

Kramer, G J; Hoeksma, J B; Prahl-Andersen, B

1993-02-01

212

Masticatory function following implants replacing a second molar  

PubMed Central

Purpose The aim of this study was to obtain objective and standardized information on masticatory function and patient satisfaction following second molar single implant therapy. Methods Twenty adult patients, who had restored second molar single implants more than 1 month before the study, were enrolled in this study. All patients received a chewing test using peanuts before and after insertion of the implant prosthesis, with a questionnaire and visual analogue scale (VAS) to evaluate the effect of second molar single implant therapy. Results This study obtained standardized information on the masticatory function objectively (e.g., P, R, X50) before (Pre-insertion) and after insertion (Post-insertion) of the implant prosthesis. Masticatory performance (P) after insertion of the implant prosthesis significantly increased from 67.8±9.9 to 84.3±8.5% (P<0.0001). With the implant prosthesis, the P value increased by 24%. The masticatory efficiency index (R) of Post-insertion is higher than that of Pre-insertion (P<0.0001). With the implant prosthesis, the R value increased by 29%. The median particle size (X50) of Post-insertion is lower than that of Pre-insertion (P<0.0001). More than 90% of the patients were satisfied with the second molar single implant therapy from a functional point of view. Conclusions These findings indicate that a second molar single implant can increase masticatory function. PMID:21556258

Kim, Moon-Sun; Lee, Jae-Kwan; Chang, Beom-Seok

2011-01-01

213

Comparison of pre/post-operative CT image volumes to preoperative digitization of partial hepatectomies: a feasibility study in surgical validation  

NASA Astrophysics Data System (ADS)

Preoperative planning combined with image-guidance has shown promise towards increasing the accuracy of liver resection procedures. The purpose of this study was to validate one such preoperative planning tool for four patients undergoing hepatic resection. Preoperative computed tomography (CT) images acquired before surgery were used to identify tumor margins and to plan the surgical approach for resection of these tumors. Surgery was then performed with intraoperative digitization data acquire by an FDA approved image-guided liver surgery system (Pathfinder Therapeutics, Inc., Nashville, TN). Within 5-7 days after surgery, post-operative CT image volumes were acquired. Registration of data within a common coordinate reference was achieved and preoperative plans were compared to the postoperative volumes. Semi-quantitative comparisons are presented in this work and preliminary results indicate that significant liver regeneration/hypertrophy in the postoperative CT images may be present post-operatively. This could challenge pre/post operative CT volume change comparisons as a means to evaluate the accuracy of preoperative surgical plans.

Dumpuri, Prashanth; Clements, Logan W.; Li, Rui; Waite, Jonathan M.; Stefansic, James D.; Geller, David A.; Miga, Michael I.; Dawant, Benoit M.

2009-02-01

214

LANDSAT-D data format control book. Volume 6, appendix A: Partially processed thematic mapper High Density Tape (HDT-AT)  

NASA Technical Reports Server (NTRS)

One of the outputs of the data management system being developed to provide a variety of standard image products from the thematic mapper and the multispectral band scanners on LANDSAT 4, is the partially processed TM data (radiometric corrections applied and geometric correction matrices for two projections appended) which is recorded on a 28-track high density tape. Specifications are presented for the format of the recorded data as well as for the time code and the major and minor frames of the tape. Major frame types, formats, and field definitions are included.

Jai, A.

1982-01-01

215

Treatment of Ectopic Mandibular Second Permanent Molar with Elastic Separators  

PubMed Central

Ectopic eruption is a developmental disturbance in which the tooth fails to follow its normal eruption pathway. Ectopic eruption of the second molar is relatively rare. This paper presents the case of thirteen-year-old male with an ectopic mandibular second permanent molar. The condition was corrected with surgical exposure and placement of elastic separators. This case report lays emphasis on the practice of basic methods to obtain acceptable results rather than extensive surgical or orthodontic corrections. It is advised that ectopic teeth should not be neglected especially when it concerns developing caries and malocclusion. PMID:25050182

Rajesh, R.; Naveen, V.; Amit, S.; Baroudi, Kusai; Sampath Reddy, C.; Namineni, Srinivas

2014-01-01

216

Clinical analysis of molar fissures by Cone-beam tomography.  

PubMed

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

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

2007-01-01

217

Endodontic Management of a Maxillary Molar with Three Mesiobuccal Canals  

PubMed Central

It is imperative that the clinician should have comprehensive knowledge about the normal anatomy and its variations of the teeth as the deviations from the usual are very common. An increased awareness of unusual anatomy and a better understanding of the root canal system guide the clinician in accurate diagnosis and treatment of such variations in order to achieve a successful endodontic outcome. The maxillary first molar has been shown to have a wide variation in respect to the number of canals specifically noted in the mesiobuccal root. The current case report shows the successful management of a maxillary molar in which the mesiobuccal root had three canals. PMID:25505997

Gundam, Sirisha; Maddu, Radhika; Gurram, Sindhura Reddy

2014-01-01

218

[Recurrent hydatidiform mole. Case report of 9 successive molar pregnancies].  

PubMed

The recurrent hydatiform mole is rare, its frequency is lower to 1%. We report the observation of a 28 years old women. without antecedents of molar pregnancy in the family and without considerable pathological antecedents. She had 9 successive molar pregnancies, without inset normal pregnancies and without living children. The delay of at least 1 year between the gestations has been respected in 6 pregnancies. The etiologic balance in particular the caryotypes of parents is normal. The authors debate the étiopathogénic and prognostic factors of this pathology. PMID:17175694

Sahraoui, Wassila; Hajji, Saloua; Haouas, Noureddine; Ladib, Noura; Essafi, Adel; Hmissa, Sihem; Bibi, Mohamed; Khairi, Hedi

2006-08-01

219

Choriocarcinoma of the bladder. Report of a case of primary tumor or late metastasis of a molar pregnancy.  

PubMed

Choriocarcinoma of the bladder was diagnosed in a 54-year-old woman presenting with macroscopic hematuria 17 years following evacuation of a molar pregnancy. The patient was treated by cystoscopic transurethral tumor resection followed by three courses of triple-agent chemotherapy and total abdominal hysterectomy with bilateral salpingo-oophorectomy. Six months later a gradual rise in beta-human chorionic gonadotropin levels led to the diagnosis of recurrent bladder tumor at the site of the previous tumor. The patient underwent a conservative partial cystectomy, and 12 months postoperatively there was no evidence of disease. It is unclear whether the patient developed a primary urinary bladder choriocarcinoma or late metastatic disease from the previous molar pregnancy. PMID:7650666

Yishai, D; Atad, J; Bornstein, J; Sova, Y; Mecz, Y; Lurie, A; Lurie, M; Abramovici, H

1995-06-01

220

RESEARCH Open Access Half-molar sodium lactate infusion improves  

E-print Network

ejection fraction respiratory failure of predominantly cardiac origin. There were no significant differences in the need for vasoactive therapy, respiratory support, renal or liver of half-molar sodium lactate improved cardiac performance and led to metabolic alkalosis in AHF patients

Paris-Sud XI, Université de

221

ABSENCE OF SEXUAL DIMORPHISM IN MOLAR MORPHOLOGY OF MUSKRATS  

E-print Network

ABSENCE OF SEXUAL DIMORPHISM IN MOLAR MORPHOLOGY OF MUSKRATS PATRICK J. LEWIS,1 Department Tech University, Lubbock, TX 79409, USA Abstract: The muskrat (Ondatra zibethicus) lives in both modern. If sexual dimorphism is present in muskrats, what is known about their interaction with the environment may

Strauss, Richard E.

222

Mathematical analysis of furcation angle in extracted mandibular molars  

PubMed Central

Background: Multi-rooted teeth with furcation involvement exhibit a poorer prognosis when compared to single rooted teeth. The furcation angle (formed by the divergent roots and the roof) may exert a considerable influence on the accessibility for both home care maintenance and instrumentation during periodontal therapy. As there are few anatomy based reports, the furcation angle has not yet been delineated. Materials and Methods: Furcation angle (FA) was mathematically evaluated in extracted mandibular first and second molar teeth, using the Computer-aided design - computer-aided manufacturing technology. Results: The furcations were divided into three groups (Group I: <30°, Group II: 30°-60°, Group III: >60°) based on the furcation angle and their prevalence. The first molar showed greater prevalence of group II FA, while second molar showed a greater prevalence of group III FA. Conclusion: Linear, two dimensional measurements may not accurately reflect the complexities of the furcation area which exhibits considerable intermolar and intramolar (buccal and lingual furcations of second molar) variation. PMID:23633776

James, Johnson R.; Arun, K. V.; Talwar, Avaneendra; Kumar, T. S. S.

2013-01-01

223

Variations in the mechanical properties of Alouatta palliata molar enamel.  

PubMed

Teeth have provided insights into many topics including primate diet, paleobiology, and evolution, due to the fact that they are largely composed of inorganic materials and may remain intact long after an animal is deceased. Previous studies have reported that the mechanical properties, chemistry, and microstructure of human enamel vary with location. This study uses nanoindentation to map out the mechanical properties of Alouatta palliata molar enamel on an axial cross-section of an unworn permanent third molar, a worn permanent first molar, and a worn deciduous first molar. Variations were then correlated with changes in microstructure and chemistry using scanning electron microscopy and electron microprobe techniques. The hardness and Young's modulus varied with location throughout the cross-sections from the occlusal surface to the dentin-enamel junction (DEJ), from the buccal to lingual sides, and also from one tooth to another. These changes in mechanical properties correlated with changes in the organic content of the tooth, which was shown to increase from approximately 6% near the occlusal surface to approximately 20% just before the DEJ. Compared to human enamel, the Alouatta enamel showed similar microstructures, chemical constituents, and magnitudes of mechanical properties, but showed less variation in hardness and Young's modulus, despite the very different diet of this species. PMID:19672851

Darnell, Laura A; Teaford, Mark F; Livi, Kenneth J T; Weihs, Timothy P

2010-01-01

224

Mandibular third molar surgery with primary closure and tube drain  

Microsoft Academic Search

The insertion of a small surgical tube drain with primary wound closure (drain group) was compared to a simple primary wound closure (no drain group) after removal of impacted third molars. Surgery was performed on 23 patients in a randomized cross-over fashion. The operation time was found to be significantly longer and mouth opening significantly wider in the immediate postoperative

Sutas Rakprasitkul; Verasak Pairuchvej

1997-01-01

225

Management of Six Root Canals in Mandibular First Molar  

PubMed Central

Success in root canal treatment is achieved after thorough cleaning, shaping, and obturation of the root canal system. This clinical case describes conventional root canal treatment of an unusual mandibular first molar with six root canals. The prognosis for endodontic treatment in teeth with abnormal morphology is unfavorable if the clinician fails to recognize extra root canals. PMID:25685156

Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

2015-01-01

226

DNA Templated Synthesis (DTS) -Nature's effective molarity based approach-  

E-print Network

Translation DNA RNA Protein Replication mRNA tRNA Nucleic acid templated synthesis plays a important roleDNA Templated Synthesis (DTS) -Nature's effective molarity based approach- Organic Seminar 27th May of many reactants in one solution macromolecule- templated synthesis selective product formation one

Katsumoto, Shingo

227

Effect of temperature on W-shaped excess molar heat capacities and volumetric properties: Oxaalkane-nonane systems  

NASA Astrophysics Data System (ADS)

Excess molar volumes V m f of the mixtures diglyme (2,5,8-trioxanonane: TON), triglyme (2.5,8,11-tetraoxadodecane: TODD), or tetraglyme (2,5,8,11,14-pen-taoxapentadecane: POPD; E181)+ n-nonane have been obtained from density measurements at 278.15, 288.15,298.15, and 308. 15 K. In addition, a micro DSC II differential scanning calorimeter was used to obtain excess molar heat capacities C p E at constant pressure for the same mixtures except for TON+ n-nonane and at the same temperatures except for 278.15 K. These results allowed us to calculate the following mixing quantities in the complete range of concentration: ?(? V {/m ?}/? T) p , and (? H ?/? p) nT at 298.15K. The excess molar volumes are positive with large maximum values located in the central concentration range with the exception of POPD + n-nonane at 278.15 K, which has a central miscibility gap. For these mixtures, C p F has a W-shaped concentration dependence: two minima separated by a maximum.

Tovar, C. A.; Carballo, E.; Cerdeiriña, C. A.; Legido, J. L.; Romani, L.

1997-05-01

228

Molar mass characterization of sodium carboxymethyl cellulose by SEC-MALLS.  

PubMed

Two series of sodium carboxymethyl celluloses (NaCMCs) derived from microcrystalline cellulose (Avicel samples) and cotton linters (BWL samples) with average degrees of substitution (DS) ranging from DS=0.45 to DS=1.55 were characterized by size exclusion chromatography with multi-angle laser light scattering detection (SEC-MALLS) in 100 mmol/L aqueous ammonium acetate (NH4OAc) as vaporizable eluent system. The application of vaporizable NH4OAc allows future use of the eluent system in two-dimensional separations employing evaporative light scattering detection (ELSD). The losses of samples during filtration and during the chromatographic experiment were determined. The scaling exponent as of the relation [Formula: see text] was approx. 0.61, showing that NaCMCs exhibit an expanded coil conformation in solution. No systematic dependencies of as on DS were observed. The dependences of molar mass on SEC-elution volume for samples of different DS can be well described by a common calibration curve, which is of advantage, as it allows the determination of molar masses of unknown samples by using the same calibration curve, irrespective of the DS of the NaCMC sample. Since no commercial NaCMC standards are available, correction factors were determined allowing converting a pullulan based calibration curve into a NaCMC calibration using the broad calibration approach. The weight average molar masses derived using the so established calibration curve closely agree with the ones determined by light scattering, proving the accuracy of the correction factors determined. PMID:23618306

Shakun, Maryia; Maier, Helena; Heinze, Thomas; Kilz, Peter; Radke, Wolfgang

2013-06-01

229

Improving limestone utilization in circulating fluidized bed combustors through the reactivation and recycle of partially utilized limestone in the ash  

SciTech Connect

The extent of utilization of limestone in a circulating fluidized bed combustor can be increased by reactivating and recycling the partially sulfated limestone present in the ash. It has been shown that the partially utilized sorbent present in the ash may be reactivated by adding water to the ash. Sorbent reactivation via hydration proceeds through the reaction of the unused portion of the sorbent, calcium oxide, with the added water. The product of this reaction, calcium hydroxide, has a molar volume larger than its calcium oxide precursor. Consequently, its formation as a result of ash hydration leads to the expansion and cracking of the partially utilized sorbent particles present in the ash. This, coupled with the pore formation accompanying the dehydration of the calcium hydroxide upon its introduction into the combustor, increases the accessibility of the unused calcium in the sorbent particles to sulfur dioxide. Bench scale tests were conducted to investigate the effect of various parameters on the reactivation of partially utilized limestone via hydration. Results of parametric tests showed that in order to maximize sorbent reactivation it is necessary to add to the ash, significantly more than the stoichiometric amount of water necessary to convert all the calcium oxide in it to calcium hydroxide. It was also observed that the extent of reactivation of the sorbent in the ash increased with the time for, and temperature at which the ash-water mixture was held.

Khan, T.; Kuivalainen, R.; Lee, Y.Y. [Ahlstrom Pyropower, Inc., San Diego, CA (United States)

1995-12-31

230

Complication of Invasive Molar Pregnancy with Clostridium perfringens Sepsis.  

PubMed

Clostridium perfringens (CP) is an anaerobic, Gram-positive bacillus associated with malignant diseases and near-term pregnancies. The necrotic tissue that results from these disease processes fuels the proliferation of CP, leading to gas gangrene and subsequently sepsis. Herein, we report a case of a 41-year-old female patient with a history of invasive molar pregnancy that was further complicated with a CP infection. Although past research has shown a link between Clostridium infection and choriocarcinoma (Chern-Horng and Hsieh, 1999), no previous cases of CP infection have been associated with invasive molar pregnancy. We also report complete resolution of the CP sepsis and its associated symptoms following the hysterectomy. PMID:24716030

Singh, Sanmeet; Angra, Kunal; Davis, Bonnie; Shokrani, Babak

2014-01-01

231

Thermal Correction to the Molar Polarizability of a Boltzmann Gas  

E-print Network

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI) for which an accurate value of the Boltzmann constant is needed. Here, we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when the probing electric field is Lorenz transformed into the rest frame of the atoms that undergo thermal motion. While this effect is small when compared to currently available experimental accuracy, the relativistic correction to the dipole interaction is much larger than the thermal shift of the polarizability induced by blackbody radiation.

Jentschura, U D; Mohr, P J

2013-01-01

232

Thermal correction to the molar polarizability of a Boltzmann gas  

SciTech Connect

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when the probing electric field is Lorentz transformed into the rest frame of the atoms that undergo thermal motion. While this effect is small when compared to currently available experimental accuracy, the relativistic correction to the dipole interaction is much larger than the thermal shift of the polarizability induced by blackbody radiation.

Jentschura, U. D. [Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Puchalski, M. [Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60-780 Poznan (Poland); Mohr, P. J. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8420 (United States)

2011-12-15

233

Thermal Correction to the Molar Polarizability of a Boltzmann Gas  

E-print Network

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI) for which an accurate value of the Boltzmann constant is needed. Here, we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when the probing electric field is Lorenz transformed into the rest frame of the atoms that undergo thermal motion. While this effect is small when compared to currently available experimental accuracy, the relativistic correction to the dipole interaction is much larger than the thermal shift of the polarizability induced by blackbody radiation.

U. D. Jentschura; M. Puchalski; P. J. Mohr

2013-09-09

234

Complication of Invasive Molar Pregnancy with Clostridium perfringens Sepsis  

PubMed Central

Clostridium perfringens (CP) is an anaerobic, Gram-positive bacillus associated with malignant diseases and near-term pregnancies. The necrotic tissue that results from these disease processes fuels the proliferation of CP, leading to gas gangrene and subsequently sepsis. Herein, we report a case of a 41-year-old female patient with a history of invasive molar pregnancy that was further complicated with a CP infection. Although past research has shown a link between Clostridium infection and choriocarcinoma (Chern-Horng and Hsieh, 1999), no previous cases of CP infection have been associated with invasive molar pregnancy. We also report complete resolution of the CP sepsis and its associated symptoms following the hysterectomy. PMID:24716030

Singh, Sanmeet; Angra, Kunal; Davis, Bonnie; Shokrani, Babak

2014-01-01

235

Molar distalization with the assistance of Temporary Anchorage Devices.  

PubMed

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

Palencar, Adrian J

2015-01-01

236

Five Canalled and Three-Rooted Primary Second Mandibular Molar  

PubMed Central

A thorough knowledge of root canal anatomy and its variation is necessary for successful completion of root canal procedures. Morphological variations such as additional root canals in human deciduous dentition are rare. A mandibular second primary molar with more than four canals is an interesting example of anatomic variations, especially when three of these canals are located in the distal root. This case shows a rare anatomic configuration and points out the importance of looking for additional canals. PMID:25147744

Selvakumar, Haridoss; Kavitha, Swaminathan; Bharathan, Rajendran; Varghese, Jacob Sam

2014-01-01

237

Articaine Infiltration for Anesthesia of Mandibular First Molars  

Microsoft Academic Search

A randomized, controlled trial of 31 healthy volunteers compared 4% articaine with 1:100,000 epinephrine buccal infiltration to buccal plus lingual infiltration of the same dose of drug in achieving pulpal anesthesia of mandibular first molar teeth. Data were compared with efficacy of an inferior alveolar nerve block using 2% lidocaine 1:80,000 epinephrine in a cohort of 27 of the volunteers.

Ian P. Corbett; Mohammad D. Kanaa; John M. Whitworth; John G. Meechan

238

No benefit from prophylactic antibiotics in third molar surgery  

Microsoft Academic Search

DesignThis was a randomised controlled trial in a hospital environment.InterventionAfter surgical removal of third molars postoperative treatment was with oral amoxicillin–clavulanic acid (AC) or clindamycin (CL) or no antibiotics (C). The surgical technique was the same in all cases, and the follow-up period was 4 weeks.Outcome measureParameters evaluated were pain, differences in mouth opening, infection, the occurrence of dry socket,

Mike Hill

2005-01-01

239

Beyond the molar-molecular distinction: we need multiscaled analyses.  

PubMed

Dinsmoor's (2001) adherence to molecular analyses may require him to assert that molar and molecular principles are mutually exclusive, but to instead analyze the phenomena of avoidance as inherently multiscaled is to follow a well-established practice in the natural sciences. Besides the issue of scale, two-factor theory, which Dinsmoor advocates, has little to say about some important and longstanding results in experiments that qualify as avoidance. PMID:11453624

Hineline, P N

2001-05-01

240

Bone Carbonate and the Ca to P Molar Ratio  

Microsoft Academic Search

IT is customary to consider the bone salt either as hydroxy-apatite or as tribasic calcium phosphate, principally on the basis of stoichiometric and X-ray diffraction studies1. Nonetheless, the observed molar ratio of Ca\\/P in the bone salt in most vertebrates is quite variable, and is usually in excess of 1.67, which is the ratio one would expect for hydroxyapatite2-4. Few

Edmund D. Pellegrino; Robert M. Biltz

1968-01-01

241

Extrusion of impacted mandibular second molar using removable appliance  

PubMed Central

The purpose of this article is to review the principles of case management of impacted mandibular molars and to illustrate their potential to respond well to treatment. Although the scope of treatment may be influenced by the patient's age, past dental history, severity of impaction, dentoalveolar development, and root form, the case reports demonstrate the inherent potential for good treatment outcome even in the most unfavorable circumstances. PMID:25210378

Karthikeyan, M. K.; Prabhakar, Ramachandran; Saravanan, R.; Vikram, N. Raj; Kumar, R. Vinoth; Prasath, R. Eshwara

2014-01-01

242

Molar Macrowear Reveals Neanderthal Eco-Geographic Dietary Variation  

PubMed Central

Neanderthal diets are reported to be based mainly on the consumption of large and medium sized herbivores, while the exploitation of other food types including plants has also been demonstrated. Though some studies conclude that early Homo sapiens were active hunters, the analyses of faunal assemblages, stone tool technologies and stable isotopic studies indicate that they exploited broader dietary resources than Neanderthals. Whereas previous studies assume taxon-specific dietary specializations, we suggest here that the diet of both Neanderthals and early Homo sapiens is determined by ecological conditions. We analyzed molar wear patterns using occlusal fingerprint analysis derived from optical 3D topometry. Molar macrowear accumulates during the lifespan of an individual and thus reflects diet over long periods. Neanderthal and early Homo sapiens maxillary molar macrowear indicates strong eco-geographic dietary variation independent of taxonomic affinities. Based on comparisons with modern hunter-gatherer populations with known diets, Neanderthals as well as early Homo sapiens show high dietary variability in Mediterranean evergreen habitats but a more restricted diet in upper latitude steppe/coniferous forest environments, suggesting a significant consumption of high protein meat resources. PMID:21445243

Fiorenza, Luca; Benazzi, Stefano; Tausch, Jeremy; Kullmer, Ottmar; Bromage, Timothy G.; Schrenk, Friedemann

2011-01-01

243

Molar macrowear reveals Neanderthal eco-geographic dietary variation.  

PubMed

Neanderthal diets are reported to be based mainly on the consumption of large and medium sized herbivores, while the exploitation of other food types including plants has also been demonstrated. Though some studies conclude that early Homo sapiens were active hunters, the analyses of faunal assemblages, stone tool technologies and stable isotopic studies indicate that they exploited broader dietary resources than Neanderthals. Whereas previous studies assume taxon-specific dietary specializations, we suggest here that the diet of both Neanderthals and early Homo sapiens is determined by ecological conditions. We analyzed molar wear patterns using occlusal fingerprint analysis derived from optical 3D topometry. Molar macrowear accumulates during the lifespan of an individual and thus reflects diet over long periods. Neanderthal and early Homo sapiens maxillary molar macrowear indicates strong eco-geographic dietary variation independent of taxonomic affinities. Based on comparisons with modern hunter-gatherer populations with known diets, Neanderthals as well as early Homo sapiens show high dietary variability in Mediterranean evergreen habitats but a more restricted diet in upper latitude steppe/coniferous forest environments, suggesting a significant consumption of high protein meat resources. PMID:21445243

Fiorenza, Luca; Benazzi, Stefano; Tausch, Jeremy; Kullmer, Ottmar; Bromage, Timothy G; Schrenk, Friedemann

2011-01-01

244

Efficacy of Postoperative Prophylactic Antibiotic Therapy in Third Molar Surgery  

PubMed Central

Introduction: Surgical extraction of mandibular third molar is the most frequently performed procedure in oral surgery. This procedure is associated with significant postoperative sequelae such as trismus, swelling, pain and infection. The need of antibiotic therapy during the removal of mandibular third molar has been a contentious issue. Method: This study investigated a regimen by using amoxycillin and metronidazole in one group and without using antibiotics in the other. Both the groups were assessed postoperatively on the 1st, 2nd, 5th, 7th and 10th days by the same observer for post operative mouth opening (interincisal distance), presence of a purulent discharge at the site of surgery, pain and swelling. Result: Overall, no statistically significant difference was seen between both the treatment groups when interincisal distance, pain, swelling and purulent discharge were considered. Conclusion: The results of this study failed to show any advantage which was associated with the routine postoperative use of antibiotics in asymptomatic third molar surgeries. PMID:24995236

Reddy B, Praveen

2014-01-01

245

40 CFR 1066.610 - Mass-based and molar-based exhaust emission calculations.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 2012-07-01 false Mass-based and molar-based exhaust emission calculations. 1066.610 Section...PROCEDURES Calculations § 1066.610 Mass-based and molar-based exhaust emission calculations. (a)...

2012-07-01

246

40 CFR 1066.610 - Mass-based and molar-based exhaust emission calculations.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 2013-07-01 false Mass-based and molar-based exhaust emission calculations. 1066.610 Section...PROCEDURES Calculations § 1066.610 Mass-based and molar-based exhaust emission calculations. (a)...

2013-07-01

247

Extra-Oral Approach for Removal of Ectopic Impacted Lower Third Molar: A Case Report  

PubMed Central

Extra oral approach for removal of the lower third molar is uncommon. This case report illustrates an example of removal of lower third molar by extra-oral approach preserving the inferior dental nerve. PMID:25584338

Vishnu, Priya; Kannadasan, Kamal; Kengagsubbiah, Srivatsa; Kumar, Senthil

2014-01-01

248

Three-dimensional evaluation of the mandibular third molars’ development in unilateral crossbite patients: A cone beam computed tomography study  

PubMed Central

Objectives: The aim was to investigate mandibular third molar (3M)'s maturation in the crossbite and normal sides by two- and three-dimensional analyses using cone beam computed tomography (CBCT). Materials and Methods: A retrospective study was performed using CBCT of 25 patients (16 females and 9 males; mean age: 16.8 ± 2.9 years) with unilateral posterior crossbite. The formation stages and the volume of the mandibular 3Ms were evaluated by means of CBCT data of the patients without knowing the crossbite side of the patients. Results: Statistically no significant differences were found in the development of the 3Ms between the crossbite and the control sides, whereas the volume of 3M was found to be less in the crossbite side than in the normal side (P = 0.021). Conclusions: A volume of 3M was found to be less in the crossbite side than in the normal side. PMID:25202221

Halicioglu, Koray; Celikoglu, Mevlut; Buyuk, Suleyman Kutalmis; Sekerci, Ahmet Ercan; Ucar, Faruk Izzet; Yavuz, Ibrahim

2014-01-01

249

Anxiety before extraction of impacted lower third molars  

PubMed Central

Objetives: Assess levels of trait anxiety, state anxiety and dental anxiety before extraction of lower third molars and check the correlation and reliability of the scales used for the measurement of preoperative anxiety. Study Design: A prospective study of patients treated with extraction of a lower third molar between September 2010 to December 2010 was carried out. A total of 125 patients were included in the study. All of them were patients of the Oral Surgery and Implantology Department (Valencia University Medical and Dental School, Valencia, Spain). Before surgery, patients had to complete a preoperative protocol with 4 scales: the STAI-T (State-Trait Anxiety Inventory-Trait) for measuring trait anxiety, the STAI-S (State-Trait Anxiety Inventory-State) for measuring state anxiety, and DAS (Dental anxiety Scale of N. Corah) and APAIS (Amsterdam Preoperative anxiety and Information Scale) for measuring dental anxiety. Results: Patients undergoing extractions of an impacted lower third molar showed low levels of trait anxiety and moderate levels of state anxiety and dental anxiety. Higher levels of trait anxiety were obtained for older patients. Women had higher mean levels of dental anxiety and state anxiety that men with a statistically significant difference in STAI-S scales, DAS, and APAIS. Patients with higher trait anxiety and state anxiety showed higher levels of dental anxiety. A significant correlation (p ? 0.01) (p = 0.00) was found between the four scales used to measure anxiety. The scale showed higher correlation was STAI-S scale. The 4 scales showed high reliability (? of C.> 0.80). Conclusions: Patients with highest levels of trait anxiety and state anxiety, had more dental anxiety. The STAI-T, STAI-S, DAS and APAIS scales provided useful information about anxiety before the extraction of lower impacted third molars. The STAI-S is the scale with highest correlation and reliability. Key words:Extraction of impacted lower third molars, preoperative anxiety, dental anxiety, trait anxiety, state anxiety. PMID:25662541

Tarazona, Beatriz; Tarazona-Álvarez, Pablo; Peñarrocha-Oltra, David; Rojo-Moreno, Juan

2015-01-01

250

Hypercementosis and concrescence of maxillary second molar with third molar: a case report and review of literature.  

PubMed

Concrescence signifies a rare developmental alteration, most commonly in maxillary molars,where two fully formed teeth with separate root canal structures are fused with cementum. Clinical detection is difficult due to lack of enamel involvement and radiographic detection may be challenging, as two dimensional images may be misdiagnosed as overlap, superimposition or close proximity of roots. Such a developmental anomaly can influence treatment outcomes for extraction, endodontic, periodontic, prosthodontic and orthodontic treatment. Legal complications could arise due to unexpected difficulties following treatment. Awareness of occurrence, incidence and post treatment implications of such anomalies is paramount for both the patient and clinician's benefit. This article discusses a case report of concrescence between two maxillary molar teeth and its management. PMID:24984682

Mohan, Bhavya

2014-06-01

251

Surgical extraction of mandibular third molar in pterygomandibular space: a case report  

PubMed Central

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposition without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology. PMID:24471052

Lee, Young-Kyu; Park, Sung-Soo

2013-01-01

252

Flow-induced chain scission as a physical route to narrowly distributed, high molar mass polymers  

E-print Network

Flow-induced chain scission as a physical route to narrowly distributed, high molar mass polymers experiments, semi-dilute aqueous solutions of high-molar mass, polydisperse polymers (PDI . 1.4) were injected decrease in PDI, to values as low as 1.12, along with the expected decrease of the average molar mass

Barron, Annelise E.

253

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642...Requirements § 1065.642 SSV, CFV, and PDP molar flow rate calculations. This section describes the equations for calculating molar flow rates from various flow...

2012-07-01

254

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642...Requirements § 1065.642 SSV, CFV, and PDP molar flow rate calculations. This section describes the equations for calculating molar flow rates from various flow...

2010-07-01

255

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642...Requirements § 1065.642 SSV, CFV, and PDP molar flow rate calculations. This section describes the equations for calculating molar flow rates from various flow...

2013-07-01

256

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642...Requirements § 1065.642 SSV, CFV, and PDP molar flow rate calculations. This section describes the equations for calculating molar flow rates from various flow...

2011-07-01

257

Variation in hominoid molar enamel thickness Tanya M. Smith a,*, Anthony J. Olejniczak a  

E-print Network

. It has been suggested that enamel thickness increases from first to third molars, perhaps due to varyingVariation in hominoid molar enamel thickness Tanya M. Smith a,*, Anthony J. Olejniczak a , Lawrence) in coronal planes of sections through the mesial and distal cusps in 57 permanent molars of Pan and 59

Smith, Tanya M.

258

Molecular Volumes and the Stokes-Einstein Equation  

ERIC Educational Resources Information Center

Examines the limitations of the Stokes-Einstein equation as it applies to small solute molecules. Discusses molecular volume determinations by atomic increments, molecular models, molar volumes of solids and liquids, and molal volumes. Presents an empirical correction factor for the equation which applies to molecular radii as small as 2 angstrom…

Edward, John T.

1970-01-01

259

Vertical bone growth following autotransplantation of the developing maxillary third molar to replace a retained mandibular permanent molar: a case report.  

PubMed

A retained permanent mandibular first molar caused arrested development and a defect of the alveolar bone in a 16-year-old girl. Extraction of the ankylosed tooth was immediately followed by autotransplantation of the developing maxillary third molar. At the 3-year follow-up examination the interproximal bone level at the autotransplanted molar was equal to that of the neighboring teeth. Cone beam computed tomography showed bone at the labial aspect of the transplant. The eruption of the autotransplanted tooth stimulated vertical alveolar bone development and repaired the bone defect. Additionally, there was closure of the posterior open bite that was initially present at the ankylosed molar site. PMID:25171037

Plakwicz, Pawe?; Czochrowska, Ewa Monika; Milczarek, Anna; Zadurska, Malgorzata

2014-01-01

260

Mandibular third molar development after mantle radiation in long-term survivors of childhood Hodgkin's disease  

SciTech Connect

Sequential panoramic radiographs were assessed for mandibular third molar development in 47 long-term survivors of childhood Hodgkin's disease after treatment with 37 Gy mantle field radiation. To make a comparison, panoramic radiographs of 149 healthy, nonirradiated children were reviewed for the presence of mandibular third molars. In children between the ages of 7 and 12 years, bilateral agenesis of mandibular third molars was more frequent in patients who had been treated with mantle radiation than in nonirradiated patients. Unilateral agenesis, crown hypoplasia, and root growth impairment of mandibular third molars were also found. Similar, apparent, radiation-induced developmental anomalies were noted in maxillary third molars of the irradiated patients.

McGinnis, J.P. Jr.; Hopkins, K.P.; Thompson, E.I.; Hustu, H.O.

1987-05-01

261

Restoration of Endodontically Treated Molars Using All Ceramic Endocrowns  

PubMed Central

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. PMID:24455318

Carlos, Roopak Bose; Thomas Nainan, Mohan; Pradhan, Shamina; Roshni Sharma; Benjamin, Shiny; Rose, Rajani

2013-01-01

262

Irregular Periapical Radiopacity in Mandibular Premolars and Molars  

PubMed Central

Increased deposition of cementum is observed in a wide number of both benign and malignant conditions. Many cases are often diagnosed during routine examination as an incidental finding. Diagnosing correctly without confusing it with other similarly appearing lesions, thus avoiding subjecting the patient to unnecessary investigations and stress, is of prime importance. We report one such case, where the patient presented with the routine complaint of a painful tooth, during the investigation of which he was also diagnosed with hypercementosis affecting the mandibular second premolars and molars bilaterally. The literature review reveals that not many cases of hypercementosis are frequently reported. PMID:24716003

Warrier, S. Aravind; Vinayachandran, Divya

2014-01-01

263

Partial oxidation catalyst  

DOEpatents

A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

Krumpelt, Michael (Naperville, IL); Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Doshi, Rajiv (Downers Grove, IL)

2000-01-01

264

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis  

PubMed Central

Objective To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45° and 90° to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0°, 5°, and 10° to the long axis of the tooth. Results With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90°. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions These results suggest that placement of OMIs between the second premolar and first molar at 45° to the cortical bone reduces the effect of bite force on OMIs. PMID:24228236

Lee, Hyeon-Jung; Lee, Kyung-Sook; Kim, Min-Ji

2013-01-01

265

Compensation trends of the angulation of first molars: retrospective study of 1403 malocclusion cases.  

PubMed

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 1403 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. PMID:24699185

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

2014-09-01

266

An Odor Interaction Model of Binary Odorant Mixtures by a Partial Differential Equation Method  

PubMed Central

A novel odor interaction model was proposed for binary mixtures of benzene and substituted benzenes by a partial differential equation (PDE) method. Based on the measurement method (tangent-intercept method) of partial molar volume, original parameters of corresponding formulas were reasonably displaced by perceptual measures. By these substitutions, it was possible to relate a mixture's odor intensity to the individual odorant's relative odor activity value (OAV). Several binary mixtures of benzene and substituted benzenes were respectively tested to establish the PDE models. The obtained results showed that the PDE model provided an easily interpretable method relating individual components to their joint odor intensity. Besides, both predictive performance and feasibility of the PDE model were proved well through a series of odor intensity matching tests. If combining the PDE model with portable gas detectors or on-line monitoring systems, olfactory evaluation of odor intensity will be achieved by instruments instead of odor assessors. Many disadvantages (e.g., expense on a fixed number of odor assessors) also will be successfully avoided. Thus, the PDE model is predicted to be helpful to the monitoring and management of odor pollutions. PMID:25010698

Yan, Luchun; Liu, Jiemin; Wang, Guihua; Wu, Chuandong

2014-01-01

267

Kinetics of the Free-Radical Polymerization of Isobornyl Methacrylate in the Presence of Polyisobutylenes of Different Molar Masses  

E-print Network

The effect of a linear polymer dissolved in a reactive monomer on the kinetics of free-radical polymerization is studied. The selected system was a solution of polyisobutylene (PIB) in isobornyl methacrylate (IBoMA). Ternary phase diagrams of PIB, IBoMA and poly(isobornyl methacrylate) (PIBoMA) were built at 80C. They were shifted to lower conversions when increasing the molar mass of PIB. Different PIBs exhibiting CPC at advanced conversions were selected for the kinetic study performed employing differential scanning calorimetry (DSC) at 80C. A simple kinetic model for free-radical polymerizations describing the relevant termination rate constant in terms of the free-volume theory, provided a consistent fitting of the polymerization rates in the conversion range where the solution remained homogeneous. Increasing the molar mass of PIB led to an increase in polymerization rate due to the decrease in free volume and the corresponding decrease of the termination rate. Increasing the amount of a particular PIB in the initial formulation led to a less marked gel effect, explained by the smaller relative variation of free volume with conversion. The dimensionless free volume of PIB obtained from the kinetic model was found to increase with the volume concentration of chain ends, as expected. Under conditions where phase separation took place at very low conversions, the overall polymerization rate exhibited the presence of two maxima (gel effects), representing the polymerization in two different phases. The first maximum was associated to the polymerization taking place in the phase lean in PIB and the second maximum was associated to the polymerization of the monomer that was initially fractionated with PIB.

Ezequiel R. Soule; Julio Borrajo; Roberto J. J. Williams

2013-11-21

268

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

PubMed

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. PMID:22025996

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

2011-01-01

269

Replantation of a maxillary second molar after removal of a third molar with a dentigerous cyst: Case report and 12-month follow-up  

PubMed Central

The aim of this study was to describe the replantation of a maxillary second right molar, which had been removed for surgical reasons in order to remove a dentigerous cyst associated with the adjacent third molar, and the case’s 12-month follow-up. A 51-year-old man presented swelling in the right maxillary area. Radiographic examination showed a large radiolucency in close proximity to the third molar, suggesting a follicular cyst. The third molar was extracted and the cyst underwent curettage. The second molar had to be extracted to enable complete removal of the cyst and to achieve primary closure of the wound, which would have been impossible without repositioning the molar. With this objective, extraoral endodontic treatment was performed, the root-end was resected and prepared with ultrasonic retrotips, and root-end filling was accomplished with MTA before the molar was replanted. At the 12-month follow-up, the tooth showed no clinical signs or symptoms, probing depth was no greater than 3 mm and radiographic examination showed no evidence of root resorption or periapical lesion. Key words:Replantation, maxillary molar, follicular cyst, dentigerous cyst. PMID:24790721

Peñarrocha-Diago, María A.; Peñarrocha-Oltra, David; Peñarrocha-Diago, Miguel

2014-01-01

270

Replantation of a maxillary second molar after removal of a third molar with a dentigerous cyst: Case report and 12-month follow-up.  

PubMed

The aim of this study was to describe the replantation of a maxillary second right molar, which had been removed for surgical reasons in order to remove a dentigerous cyst associated with the adjacent third molar, and the case's 12-month follow-up. A 51-year-old man presented swelling in the right maxillary area. Radiographic examination showed a large radiolucency in close proximity to the third molar, suggesting a follicular cyst. The third molar was extracted and the cyst underwent curettage. The second molar had to be extracted to enable complete removal of the cyst and to achieve primary closure of the wound, which would have been impossible without repositioning the molar. With this objective, extraoral endodontic treatment was performed, the root-end was resected and prepared with ultrasonic retrotips, and root-end filling was accomplished with MTA before the molar was replanted. At the 12-month follow-up, the tooth showed no clinical signs or symptoms, probing depth was no greater than 3 mm and radiographic examination showed no evidence of root resorption or periapical lesion. Key words:Replantation, maxillary molar, follicular cyst, dentigerous cyst. PMID:24790721

Peñarrocha-Diago, María A; Aloy-Prósper, Amparo; Peñarrocha-Oltra, David; Peñarrocha-Diago, Miguel

2014-04-01

271

Chapter 12 Partial-Volume Bayesian Classification  

E-print Network

Department of Computer Science Brown University Providence, RI 02912 dhl@cs.brown.edu Kurt W. Fleischer Pixar Animation Studios Richmond, CA 94804 kurt@pixar.com Alan H. Barr Computer Graphics Laboratory Department. The size of regions that are classified is chosen to match the spacing of the samples because the spacing

Laidlaw, David

272

A geometric morphometric analysis of hominin upper first molar shape.  

PubMed

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 believe that the analysis of this particular tooth could be more conclusive for taxonomic assignment. In this study, we have applied geometric morphometric methods to explore the morphological variability of the upper first molar (M(1)) across the human fossil record. Our emphasis focuses on the study of the phenetic relationships among the European middle Pleistocene populations (designated as H. heidelbergensis) with H. neanderthalensis and H. sapiens, but the inclusion of Australopithecus and early Homo specimens has helped us to assess the polarity of the observed traits. H. neanderthalensis presents a unique morphology characterized by a relatively distal displacement of the lingual cusps and protrusion in the external outline of a large and bulging hypocone. This morphology can be found in a less pronounced degree in the European early and middle Pleistocene populations, and reaches its maximum expression with the H. neanderthalensis lineage. In contrast, modern humans retain the primitive morphology with a square occlusal polygon associated with a round external outline. PMID:17599390

Gómez-Robles, A; Martinón-Torres, M; Bermúdez de Castro, J M; Margvelashvili, A; Bastir, M; Arsuaga, J L; Pérez-Pérez, A; Estebaranz, F; Martínez, L M

2007-09-01

273

Evolutionary novelty in a rat with no molars  

PubMed Central

Rodents are important ecological components of virtually every terrestrial ecosystem. Their success is a result of their gnawing incisors, battery of grinding molars and diastema that spatially and functionally separates the incisors from the molars. Until now these traits defined all rodents. Here, we describe a new species and genus of shrew-rat from Sulawesi Island, Indonesia that is distinguished from all other rodents by the absence of cheek teeth. Moreover, rather than gnawing incisors, this animal has bicuspid upper incisors, also unique among the more than 2200 species of rodents. Stomach contents from a single specimen suggest that the species consumes only earthworms. We posit that by specializing on soft-bodied prey, this species has had no need to process food by chewing, allowing its dentition to evolve for the sole purpose of procuring food. Thus, the removal of functional constraints, often considered a source of evolutionary innovations, may also lead to the loss of the very same traits that fuelled evolutionary diversification in the past. PMID:22915626

Esselstyn, Jacob A.; Achmadi, Anang Setiawan; Rowe, Kevin C.

2012-01-01

274

Nanoparticle counting: towards accurate determination of the molar concentration.  

PubMed

Innovations in nanotechnology have brought tremendous opportunities for the advancement of many research frontiers, ranging from electronics, photonics, energy, to medicine. To maximize the benefits of nano-scaled materials in different devices and systems, precise control of their concentration is a prerequisite. While concentrations of nanoparticles have been provided in other forms (e.g., mass), accurate determination of molar concentration, arguably the most useful one for chemical reactions and applications, has been a major challenge (especially for nanoparticles smaller than 30 nm). Towards this significant yet chronic problem, a variety of strategies are currently under development. Most of these strategies are applicable to a specialized group of nanoparticles due to their restrictions on the composition and size range of nanoparticles. As research and uses of nanomaterials are being explored in an unprecedented speed, it is necessary to develop universal strategies that are easy to use and are compatible with nanoparticles of different sizes, compositions, and shapes. This review outlines the theories and applications of current strategies to measure nanoparticle molar concentration, discusses the advantages and limitations of these methods, and provides insights into future directions. PMID:25099190

Shang, Jing; Gao, Xiaohu

2014-11-01

275

Comparison of mandibular first molar mesial root canal morphology using micro-computed tomography and clearing technique.  

PubMed

Abstract Objective. Micro-computed tomography (MCT) with alternative image reformatting techniques shows complex and detailed root canal anatomy. This study compared two-dimensional (2D) and 3D MCT image reformatting with standard tooth clearing for studying mandibular first molar mesial root canal morphology. Materials and methods. Extracted human mandibular first molar mesial roots (n = 31) were scanned by MCT (Skyscan 1172). 2D thin-slab minimum intensity projection (TS-MinIP) and 3D volume rendered images were constructed. The same teeth were then processed by clearing and staining. For each root, images obtained from clearing, 2D, 3D and combined 2D and 3D techniques were examined independently by four endodontists and categorized according to Vertucci's classification. Fine anatomical structures such as accessory canals, intercanal communications and loops were also identified. Results. Agreement among the four techniques for Vertucci's classification was 45.2% (14/31). The most frequent were Vertucci's type IV and then type II, although many had complex configurations that were non-classifiable. Generally, complex canal systems were more clearly visible in MCT images than with standard clearing and staining. Fine anatomical structures such as intercanal communications, accessory canals and loops were mostly detected with a combination of 2D TS-MinIP and 3D volume-rendering MCT images. Conclusions. Canal configurations and fine anatomic structures were more clearly observed in the combined 2D and 3D MCT images than the clearing technique. The frequency of non-classifiable configurations demonstrated the complexity of mandibular first molar mesial root canal anatomy. PMID:25385684

Kim, Yeun; Perinpanayagam, Hiran; Lee, Jong-Ki; Yoo, Yeon-Jee; Oh, Soram; Gu, Yu; Lee, Seung-Pyo; Chang, Seok Woo; Lee, Woocheol; Baek, Seung-Ho; Zhu, Qiang; Kum, Kee-Yeon

2014-11-11

276

Pressure, relaxation volume, and elastic interactions in charged simulation cells  

NASA Astrophysics Data System (ADS)

The ab initio calculation of charged supercells within density-functional theory is a necessary step to access several important properties of matter. The relaxation volume of charged point defects or the partial molar volume of ions in solution are two such examples. However, the total energy and therefore the pressure of charged systems is not uniquely defined when periodic boundary conditions are employed. This problem is tightly related to the origin of the electrostatic potential in periodic systems. This effect can be easily observed by modifying the electrostatic convention or modifying the local ionic potential details. We propose an approach to uniquely define the pressures in charged supercells with the use of the absolute deformation potentials. Only with such a definition could the ab initio calculations provide meaningful values for the relaxation volumes and for the elastic interactions for charged defects in semiconductors or ions in solution. The proposed scheme allows one to calculate sensible data even when charge neutrality is not enforced, thus going beyond the classical force-field-based approaches.

Bruneval, Fabien; Varvenne, Céline; Crocombette, Jean-Paul; Clouet, Emmanuel

2015-01-01

277

Sex determination potential of permanent maxillary molar widths and cusp diameters in a North Indian population  

PubMed Central

Aims: To assess the sex discrimination potential of permanent maxillary molar crown widths and cusp diameters. Materials and Methods: Measurements were made on plaster casts of 200 individuals of known sex (100 males, 100 females, aged 12-21 years). Eight parameters were measured on the first and second maxillary molars with a digital caliper [buccolingual, mesiodistal, mesiobuccal-distolingual and distobuccal-mesiolingual crown widths and cusp diameters (hypocone, protocone, paracone, and metacone)]. The percentage of sexual dimorphism for each parameter was calculated. Discriminant function analysis was used to determine the accuracy of sex determination for each molar separately and both the molars taken together. Results: The highest sexual dimorphism was shown by protocone in the first molar and hypocone in the second molar. Furthermore, the sex determination accuracy was highest when the first molar was taken alone than when the second molar or the first and second molars were taken together. Conclusion: Based on this study, odontometric measurements of maxillary molars provide low to moderate sex determination accuracy. PMID:24987643

Sharma, Payal; Singh, Tushita; Kumar, Piush; Chandra, Pavan Kumar; Sharma, Rakesh

2013-01-01

278

An in vitro morphological investigation of the endodontic spaces of third molars.  

PubMed

Aim of this paper was to investigate the particular anatomic features of the endodontic space of third molars in the general population of Croatia. A total of 106 fully developed third molars (56 maxillar and 50 mandibular) has been analyzed. The respective number of roots and of root canals, the structure of the roots, and the curvature and absolute length of the root-canals were analyzed. In most cases, upper third molars had three roots (83.9%), while most of the lower molars were single rooted (56.0%). Upper third molars had mostly three root canals (75.1%), lower third molars two (90.0%). In both jaws, most third molars had curved canals (60.7% in the upper and 84.0% in the lower jaw). 12.5% of upper third molars had lateral and accessory canals, whereas only 4.0% of the lower third molars were found to have them. The Student t-test showed statistically significant differences (p < 0.05) in the length of the root-canals, mesiobuccal and distobuccal canals being significantly shorter than palatinal canals. The same test showed that in the lower third molars the mesial root canals were significantly longer that the distal ones, although slightly. The results obtained are in compliance with similar results by other authors; however, they tend to show some specific population-related features. PMID:23940986

Cosi?, Jozo; Gali?, Nada; Vodanovi?, Marin; Njemirovskij, Vera; Segovi?, Sanja; Paveli?, Bozidar; Ani?, Ivica

2013-06-01

279

Molarity (Aromic Density) of the Elements as Pure Crystals.  

ERIC Educational Resources Information Center

Provides background information for teachers on the atomic density of the elements as pure crystals. Atomic density is defined as the reciprocal of the atomic volume. Includes atomic-density diagrams which were prepared using the atomic-volume values given by Singman, supplemented by additional values for some allotropes. (JN)

Pauling, Linus; Herman, Zelek S.

1985-01-01

280

[The pendulis appliance: a palatal miniscrew supported molar distalization device].  

PubMed

The maxillary molar distalization is a valuable therapeutic option in some clinical cases. Its biomechanics is challenging and difficult to obtain. Historically, various devices have been described offering successful solutions to this problem such as the Hilgers Pendulum Appliance (1992) and variants linked to mini screws which recently have shown interesting clinical potential. This article presents a new Pendulum variant using a miniscrew, the "pendulis". It follows the original concept (titanium-molybdenum alloy distalization springs and polymethyl-methacrylate pellet) but dental support is replaced by a single palatal miniscrew (median adults, para-median in children) to which the device is fixed by means of a metal welded cap easily positioned and removable by the practitioner. This allows for better control of the oral hygiene and completely controlled extraoral activation. Fabrication steps are described and instruction of use is illustrated with clinical documentation. PMID:25158749

Nappée-Miévilly, Magali; Nappée, François-Joseph; Kerbrat, Jean-Baptiste; Goudot, Patrick

2014-09-01

281

Ectopic third molar in the mandibular sigmoid notch: Report of a case and literature review  

PubMed Central

Purpose: To evaluate the etiopathogenesis, clinical features and surgical approaches for removal of ectopic third molars in the mandible. Methods: We report a case of an impacted mandibular third molar dislocated on mandibular sigmoid notch. 20 cases of ectopic mandibular third molars reported in the English-language literature, identified from Pubmed and Medline databases are also reviewed. Results: Among the 20 article reported in the presented study, ectopic third molars were generally located in the condylar region. The common symptoms of the clinical examination were pain, trismus, swelling, temporomandibular joint syndroms or no symptoms. Conclusions: Ectopic third molar may be asymptomatic initially with clinical manifestations, later on as adjacent structures are affected. The surgical approach must be carefully planned for the aim of choosing the more conservative technique that produces the minimum trauma to patients. Key words:Ectopic third molar, sigmoid notch, cyst.

Baykul, Timuçin

2015-01-01

282

Recovery after third molar surgery: Clinical and health-related quality of life outcomes  

Microsoft Academic Search

Purpose: The study goal was to assess both clinical and health-related quality of life (HRQOL) outcomes after third molar surgery. Methods: Patients who were having 4 third molars removed were enrolled in a prospective clinical trial. Baseline data were recorded that included demographics, the patient[apos ]s and surgeon[apos ]s assessment of third molar conditions, and details of the surgical procedure.

Raymond P. White; Daniel A. Shugars; David M. Shafer; Daniel M. Laskin; Michael J. Buckley; Ceib Phillips

2003-01-01

283

Third-molar impaction diagnostic with cone-beam computerized tomography  

Microsoft Academic Search

Precise three-dimensional localization of impacted third molars as it relates to the inferior dental canal (IDC) is critical to their clinical management and highly influences surgical outcomes. Recently introduced dental 3D volumetric imaging systems coupled with semi-automatic modelling techniques allows 3D visualization of the IDC and the third molar. In this study, the spatial relationship of impacted third molars is

Reyes Enciso; Robert A. Danforth; Emanuel S. Alexandroni; Ahmed Memon; James Mah

2005-01-01

284

UPPER VS. LOWER MOLARS FOR CEMENTUM ANNULI AGE DETERMINATION OF DEER  

Microsoft Academic Search

Ages were determined for 23 black-tailed deer (Odocoileus hemionus columbianus) and 14 white-tailed deer (0. virginianus) by examination of cementum annuli of both upper and lower 1st molars. Although estimated ages were virtually the same for both upper and lower molars, the clarity of annuli was significantly greater in upper molars for both species. Abstract: Ages were determined for 23

DALE R. McCULLOUGH; PAUL BEIER

285

Relationship between cusp size and occlusal wear pattern in Neanderthal and Homo sapiens first maxillary molars.  

PubMed

Tooth wear studies in mammals have highlighted the relationship between wear facets (attritional areas produced during occlusion by the contact between opposing teeth) and physical properties of the ingested food. However, little is known about the influence of tooth morphology on the formation of occlusal wear facets. We analyzed the occlusal wear patterns of first maxillary molars (M(1) s) in Neanderthals, early Homo sapiens, and contemporary modern humans. We applied a virtual method to analyze wear facets on the crown surface of three-dimensional digital models. Absolute and relative wear facet areas are compared with cusp area and cusp height. Although the development of wear facets partially follows the cusp pattern, the results obtained from the between-group comparisons do not reflect the cusp size differences characterizing these groups. In particular, the wear facets developed along the slopes of the most discriminate cusp between Neanderthals and Homo sapiens (hypocone) do not display any significant difference. Moreover, no correlations have been found between cusp size and wear facet areas (with the exception of the modern sample) and between cusp height and wear facet areas. Our results suggest that cusp size is only weakly related to the formation of the occlusal wear facets. Other factors, such as, diet, food processing, environmental abrasiveness, and nondietary habits are probably more important for the development and enlargement of wear facets, corroborating the hypotheses suggested from previous dental wear studies. PMID:21337711

Fiorenza, Luca; Benazzi, Stefano; Viola, Bence; Kullmer, Ottmar; Schrenk, Friedemann

2011-03-01

286

Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement  

PubMed Central

Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal. PMID:23349584

Torabzadeh, Hassan; Asgary, Saeed

2013-01-01

287

A Prospective Study of Clinical Outcomes Related to Third Molar Removal or Retention  

PubMed Central

Objectives. We investigated outcomes of third molar removal or retention in adolescents and young adults. Methods. We recruited patients aged 16 to 22 years from a dental practice–based research network in the Pacific Northwest from May 2009 through September 2010 who had at least 1 third molar present and had never undergone third molar removal. Data were acquired via questionnaire and clinical examination at baseline, periodic online questionnaires, and clinical examination at 24 months. Results. A total of 801 patients participated. Among patients undergoing third molar removal, rates of paresthesia and jaw joint symptoms lasting more than 1 month were 6.3 and 34.3 per 100 person-years, respectively. Among patients not undergoing removal, corresponding rates were 0.7 and 8.8. Periodontal attachment loss at distal sites of second molars did not significantly differ by third molar removal status. Incident caries at the distal surfaces of second molars occurred in fewer than 1% of all sites. Conclusions. Rates of paresthesia and temporomandibular joint disorder were higher after third molar removal. Periodontal attachment loss and incident caries at the distal sites of second molars were not affected by extraction status. PMID:24524521

Cunha-Cruz, Joana; Rothen, Marilynn; Spiekerman, Charles; Drangsholt, Mark; Anderson, Loren; Roset, Gayle A.

2014-01-01

288

VOLUME 78, NUMBER 5 P H Y S I C A L R E V I E W L E T T E R S 3 FEBRUARY 1997 Fractal Model for Coarse-Grained Nonlinear Partial Differential Equations  

E-print Network

for Coarse-Grained Nonlinear Partial Differential Equations Alberto Scotti and Charles Meneveau Department) Spatially coarse-grained (or effective) versions of nonlinear partial differential equations must be closed differential equations (PDEs) that govern processes which display scale invariance (fractality) at small length

Scotti, Alberto

289

Concentration dependence of surface properties and molar volume of multicomponent system indium-tin-lead-bismuth  

NASA Astrophysics Data System (ADS)

The results of an experimental research of surface properties of the four-component system indium-tin-lead-bismuth are presented. The researches under discussion were carried out in a combined device in which the surface tension (?) is measured by the method of maximum pressure in a drop, and density (?) is measured by advanced aerometry. Measurement errors are 0.7 % for surface tension measurement, and 0.2 % for density measurement. The study of the concentration dependence of ? in this system has revealed the influence of the third and fourth components upon the characteristics of surface tension isotherms of the binary system indium-tin. It was found out that with an increase in the content of the third and fourth components the depth of the minimum on the surface tension isotherms of the indium-tin system ? decreases. On the basis of the concentration dependence of the phenomenon of concentration bufferity is revealed. It is shown that despite the complex character, isotherms of ? on beam sections of a multicomponent system do not contain qualitatively new features in comparison with the isotherms of these properties in lateral binary systems.

R, Dadashev; R, Kutuev; D, Elimkhanov

2008-02-01

290

A method for estimating both the solubility parameters and molar volumes of liquids  

NASA Technical Reports Server (NTRS)

Development of an indirect method of estimating the solubility parameter of high molecular weight polymers. The proposed method of estimating the solubility parameter, like Small's method, is based on group additive constants, but is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of structural formula of the compound.

Fedors, R. F.

1974-01-01

291

Measurements on Melting Pressure, Metastable Solid Phases, and Molar Volume of Univariant Saturated Helium Mixture  

NASA Astrophysics Data System (ADS)

A concentration-saturated helium mixture at the melting pressure consists of two liquid phases and one or two solid phases. The equilibrium system is univariant, whose properties depend uniquely on temperature. Four coexisting phases can exist on singular points, which are called quadruple points. As a univariant system, the melting pressure could be used as a thermometric standard. It would provide some advantages compared to the current reference, namely pure He, especially at the lowest temperatures below 1 mK. We have extended the melting pressure measurements of the concentration-saturated helium mixture from 10 to 460 mK. The density of the dilute liquid phase was also recorded. The effect of the equilibrium crystal structure changing from hcp to bcc was clearly seen at mK at the melting pressure MPa. We observed the existence of metastable solid phases around this point. No evidence was found for the presence of another, disputed, quadruple point at around 400 mK. The experimental results agree well with our previous calculations at low temperatures, but deviate above 200 mK.

Rysti, J.; Manninen, M. S.; Tuoriniemi, J.

2014-06-01

292

First molar cross-bite is more closely associated with a reverse chewing cycle than anterior or pre-molar cross-bite during mastication.  

PubMed

A posterior cross-bite is defined as an abnormal bucco-lingual relationship between opposing molars, pre-molars or both in centric occlusion. Although it has been reported that patients with unilateral posterior cross-bite often show unique chewing patterns, the relationship between the form of cross-bite and masticatory jaw movement remains unclear in adult patients. The objective of this study was to investigate masticatory jaw movement among different forms of cross-bite. One hundred and one adults were recruited in this study: 27 had unilateral first molar cross-bite (MC group); 28, unilateral pre-molar cross-bite (PC group); 23, anterior cross-bite (AC group); and 23, normal occlusion (control group). Masticatory jaw movement of the lower incisor point was recorded with six degrees of freedom jaw-tracking system during unilateral mastication. Our results showed that the reverse chewing ratio during deliberate unilateral mastication was significantly larger in the MC group than in the PA (P < 0.001), AC (P < 0.001) and control (P < 0.001) groups. These findings suggest that compared to the anterior or pre-molar cross-bite, the first molar cross-bite is more closely associated with a higher prevalence of a reverse chewing cycle. PMID:25158937

Tomonari, H; Ikemori, T; Kubota, T; Uehara, S; Miyawaki, S

2014-12-01

293

Influence of cervical preflaring on determinationof apical file size in mandibular molars: SEM analysis  

Microsoft Academic Search

This study investigated the influence of cervical preflaring with different rotary instruments on determination of the initial apical file (IAF) in mesiobuccal roots of mandibular molars. Fifty human mandibular molars whose mesial roots presented two clearly separated apical foramens (mesiobuccal and mesiolingual) were used. After standard access opening and removal of pulp tissue, the working length (WL) was determined at

Marcia da Silva Schmitz; Roberto Santos; Alexandre Capelli; Marcos Jacobovitz; Júlio César Emboava Spanó; Jesus Djalma Pécora

2008-01-01

294

Grafting mandibular third molar extraction sites: A comparison of bioactive glass to a nongrafted site  

Microsoft Academic Search

Objective. The purpose of this study was to evaluate the effectiveness of bioactive glass used as a graft material for regeneration of bone after the removal of impacted third molars. The healing distal to the second molars was followed, with documentation of the level of radiographic osseous fill and measurement of the changes in clinical attachment levels. Methods. Fourteen (5

Roger R. Throndson; S. Barrett Sexton

2002-01-01

295

Degradation of Ultra-High Molar Mass Polymers in Size-Exclusion Chromatography  

Technology Transfer Automated Retrieval System (TEKTRAN)

The degradation of high molar mass polymers during size-exclusion chromatography (SEC) analysis has been a topic of interest for several decades. Should a polymer degrade during analysis, the accuracy of the molar mass (M) and architectural information obtained will be compromised. To this effect,...

296

Evaluation of factors predictive of lingual nerve injury in third molar surgery  

Microsoft Academic Search

The aim of this study was to investigate risk factors for temporary and permanent lingual nerve injury after extraction of mandibular third molars. It was based on a 4-year prospective study of 2134 consecutive mandibular third molar operations in 1384 consecutive day case patients. During the study period (1994–1998) data were collected prospectively on patient, dental and surgical factors and

T. Renton; M. McGurk

2001-01-01

297

Postoperative prophylactic antibiotic treatment in third molar surgery—a necessity?  

Microsoft Academic Search

Purpose: We evaluated the need for prophylactic postoperative oral antibiotic treatment in the removal of asymptomatic third molars.Materials and Methods: In a prospective study of more than 30 months, a total of 528 impacted lower third molars were surgically removed in 288 patients. All patients were referred to our department by a dentist or a general practitioner. No patient showed

Paul W Poeschl; Doris Eckel; Ellen Poeschl

2004-01-01

298

The relationship of the lingual nerve to the mandibular third molar region: An anatomic study  

Microsoft Academic Search

Purpose: This study evaluated the relationship of the mandibular third molar to the lingual nerve.Materials and Methods: An anatomic dissection of the lingual nerve in the third molar region was done on 20 cadavers (40 sides).Results: The position of the nerve on one side bore no statistical relationship to the position of the nerve on the opposite side. The position

M. Anthony Pogrel; Andrew Renaut; Brian Schmidt; Awnie Ammar

1995-01-01

299

Developing a measure of patient perceptions of short-term outcomes of third molar surgery  

Microsoft Academic Search

Purpose: The purpose of the study was to develop an instrument to measure patients' perceptions of their experiences after the removal of third molar teeth.Methods: Nineteen patients (ages 18 to 25 years) who underwent surgical removal of four third molars after local treatment for mild symptoms of pericoronitis completed a newly developed 14-item instrument each evening for the 14-day period

Daniel A Shugars; Ken Benson; Raymond P White; Kit N Simpson; James D Bader

1996-01-01

300

Panoramic radiographic risk factors for inferior alveolar nerve injury after third molar extraction  

Microsoft Academic Search

Purpose: The purpose of this study was to estimate the association between specific panoramic radiographic signs and inferior alveolar nerve (IAN) injury during mandibular third molar removal. Patients and Methods: A case-control study design was used; the sample consisted of patients who underwent removal of impacted mandibular third molars. Cases were defined as patients with confirmed IAN injury after third

Bart F. Blaeser; Meredith A. August; R. Bruce Donoff; Leonard B. Kaban; Thomas B. Dodson

2003-01-01

301

Association between third molar agenesis patterns and agenesis of other teeth in a Japanese orthodontic population.  

PubMed

The purpose of this study was to investigate the patterns of third molar agenesis and incidence of agenesis of other permanent teeth in a Japanese orthodontic patient group. A total of 417 Japanese subjects (134 males and 283 females) with agenesis of one or more third molars were divided into four groups according to the agenesis pattern, and 874 other Japanese subjects (302 males and 572 females) without third molar agenesis were assigned to a control group. Panoramic radiographs and medical and dental records were used to examine for tooth agenesis. The Chi-square test and odds ratio were used to make statistical comparisons. The prevalence of third molar agenesis worked out at 32.3% with no statistically significant gender difference. A high prevalence rate of agenesis of third molars, unilateral or bilateral, could be considered characteristic of the Japanese orthodontic population. Significant increases in occurrence of oligodontia, and unilateral or bilateral agenesis of other teeth, including maxillary lateral incisors and maxillary and mandibular second premolars, were observed in all or almost all of the third molar agenesis groups, compared with the controls. A significantly increased prevalence rate of mandibular lateral incisor agenesis was observed in almost all of the third molar agenesis groups. The Japanese patients with third molar agenesis had a significantly increased occurrence of oligodontia, and unilateral or bilateral agenesis of maxillary and mandibular lateral incisors and second premolars, except for bilateral agenesis of mandibular lateral incisors. PMID:23990107

Endo, Saori; Sanpei, Sugako; Ishida, Rieko; Sanpei, Shinya; Abe, Ryota; Endo, Toshiya

2015-01-01

302

Prevalence of Three-rooted Mandibular First Molars among Taiwanese Individuals  

Microsoft Academic Search

The purpose of this study was to evaluate the prevalence of mandibular first molars featuring a distolingual root among a Taiwanese population. A total of 731 patients’ periapical radiographs were screened and examined to obtain 166 samples for this study. The gender, symmetry, and frequencies of occurrence of three-rooted mandibular first molars were recorded. The prevalence of three-rooted mandibular first

Ming-Gene Tu; Chi-Cheng Tsai; Ming-Jia Jou; Wil-Lie Chen; Yu-Fang Chang; San-Yue Chen; Hui-Wen Cheng

2007-01-01

303

A new method to correct lingual rolling of lower molars (Amini twister).  

PubMed

In this report, we present an uncomplicated approach to overcome lingual rolling of mandibular molars during orthodontic treatment, by using rectangular NiTi arch wire in twist fashion through the molar tube. The sequential steps of the twist manoeuvre on a typodont and a case report are exhibited in this article. PMID:23729138

Amini, Fariborz; Poosti, Maryam

2013-01-01

304

Phase-separation-induced fractionation in molar mass in aqueous mixtures of gelatin and dextran.  

PubMed

An overview of the effects of phase separation of aqueous mixtures of gelatin and dextran on the fractionation in molar mass of these two components is given. Molar mass distributions in coexisting phases were investigated using size exclusion chromatography with multiangle laser light scattering. The initial molar mass of the native material, concentration, and temperature were varied. The results show a strong fractionation in molar mass for both components. The molar mass of the native material and concentration appeared to be the only factors that affected the final molar mass distributions, temperature having no effect. The results show that in the molar mass range where fractionation is the strongest, i.e., roughly below the maximum in the distribution, fractionation is governed by a Boltzmann factor e(-deltaG/kT), where deltaG denotes the free energy involved in transferring a polymer with a certain length from the enriched to the depleted phase, and in this case turns out to be proportional to the molar mass. Comparison of the results of phase separation with results on dialysis shows that water affinity is not the driving force for the phase separation of gelatin and dextran in aqueous solution. The gelation properties of gelatin in both phases were also determined. The gelation properties of gelatin in the coexisting phases differ from those of native gelatin. In particular, the gelatin in the gelatin-poor phase shows strong differences compared to the native material. PMID:12636676

Edelman, M W; Tromp, R H; van der Linden, E

2003-02-01

305

Excess molar enthalpies of chloroalkanes or chloroalkene + 2-propyn-1-ol at 298.15 K  

SciTech Connect

Excess molar enthalpies for 2-propyn-1-ol + 1,2-dichloroethane, + 1,1,1,-trichloroethane, + 1,1,2,2-tetrachloroethane, and + trichloroethylene have been measured at 298.15 K with a Parr 1451 solution calorimeter. The excess molar enthalpies are positive over the entire range of composition.

Kumar, R.V.; Rao, M.A.; Rao, M.V. [Osmania Univ., Hyderabad (India). Dept. of Chemistry; Prasad, D.H.L. [Indian Inst. of Tech., Hyderabad (India)

1995-09-01

306

Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus indicus  

E-print Network

Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus of the first data for molar crown development in one hominoid genus, Sivapi- thecus. The data are compared to a range of extant and extinct hominoids. Crown formation times (CFTs), daily rates of enamel secretion

Smith, Tanya M.

307

Uniquely derived upper molar morphology of Eocene Amphipithecidae (Primates: Anthropoidea): homology and phylogeny.  

PubMed

The extinct Southeast Asian primate family Amphipithecidae is regularly cited in discussions of anthropoid origins, but its phylogenetic position remains controversial. In part, the lack of consensus regarding amphipithecid relationships can be attributed to uncertainty regarding the homology of upper molar structures in this group. Here, we describe a virtually pristine upper molar of Pondaungia cotteri from the late middle Eocene Pondaung Formation of Myanmar, which is the first example of a relatively unworn and well-preserved amphipithecid upper molar ever recovered. The distolingual upper molar cusp in this new specimen of Pondaungia appears to be a lingually displaced and enlarged metaconule, rather than a hypocone or pseudohypocone as previous workers have thought. Reassessment of the upper molar morphology of other amphipithecids and putative amphipithecids reveals a very similar pattern in Siamopithecus, Myanmarpithecus and Ganlea, all of which are interpreted as having upper molars showing many of the same derived features apparent in Pondaungia. In contrast, the upper molar morphology of Bugtipithecus diverges radically from that of undoubted amphipithecids, and the latter taxon is excluded from Amphipithecidae on this basis. Phylogenetic analyses of several character-taxon matrices culled from the recent literature and updated to reflect the new information on amphipithecid upper molar morphology yield similar results. Consensus tree topologies derived from these analyses support amphipithecid monophyly and stable relationships within Amphipithecidae. Amphipithecids appear to be stem members of the anthropoid clade. PMID:23823753

Coster, Pauline; Beard, K Christopher; Soe, Aung Naing; Sein, Chit; Chaimanee, Yaowalak; Lazzari, Vincent; Valentin, Xavier; Jaeger, Jean-Jacques

2013-08-01

308

Removal of an upper third molar from the maxillary sinus.  

PubMed

The maxillary sinus or antrum is the largest of the paranasal sinuses. It is located in the maxillary bone and has a proximity to the apexes of upper molars and premolars, which allows it to form a direct link between the sinus and the oral cavity. Dislocation of a foreign body or tooth to the interior of a paranasal sinus is a situation that can occur as a result of car accidents, firearm attacks, or iatrogenic in surgical procedures. Therefore, it is necessary to know how to treat this kind of situation. This study's objective is to report the case of a 23-year-old female patient, leucoderma, who sought treatment from the Surgical Unit at the Dental Faculty of the Federal University of Sergipe. She had a history of pain and edema in the right side of the genian region and two failed attempts at removing dental unit (DU) 18. The extraoral clinical exam revealed intense edema of the left hemiface with signs of infection, excoriation of the labial commissure, hematoma, a body temperature of 39°C, and a limited ability to open her mouth. The patient was medicated and treated surgically. The tooth was removed from the maxillary sinus with caution, as should have been done initially. PMID:25705524

Amorim, Klinger de Souza; da Silva, Vanessa Tavares; da Cunha, Rafael Soares; Souto, Maria Luisa Silveira; São Mateus, Carla Rocha; Souza, Liane Maciel de Almeida

2015-01-01

309

Removal of an Upper Third Molar from the Maxillary Sinus  

PubMed Central

The maxillary sinus or antrum is the largest of the paranasal sinuses. It is located in the maxillary bone and has a proximity to the apexes of upper molars and premolars, which allows it to form a direct link between the sinus and the oral cavity. Dislocation of a foreign body or tooth to the interior of a paranasal sinus is a situation that can occur as a result of car accidents, firearm attacks, or iatrogenic in surgical procedures. Therefore, it is necessary to know how to treat this kind of situation. This study's objective is to report the case of a 23-year-old female patient, leucoderma, who sought treatment from the Surgical Unit at the Dental Faculty of the Federal University of Sergipe. She had a history of pain and edema in the right side of the genian region and two failed attempts at removing dental unit (DU) 18. The extraoral clinical exam revealed intense edema of the left hemiface with signs of infection, excoriation of the labial commissure, hematoma, a body temperature of 39°C, and a limited ability to open her mouth. The patient was medicated and treated surgically. The tooth was removed from the maxillary sinus with caution, as should have been done initially. PMID:25705524

Amorim, Klinger de Souza; da Silva, Vanessa Tavares; da Cunha, Rafael Soares; Souto, Maria Luisa Silveira; São Mateus, Carla Rocha; Souza, Liane Maciel de Almeida

2015-01-01

310

Joubert syndrome: congenital cerebellar ataxia with the “molar tooth”  

PubMed Central

Joubert syndrome (JS) is a congenital cerebellar ataxia with autosomal recessive or X-linked inheritance, which diagnostic hallmark is a unique cerebellar and brainstem malformation recognizable on brain imaging, the “molar tooth sign”. Neurological signs are present from neonatal age and include hypotonia evolving into ataxia, global developmental delay, ocular motor apraxia and breathing dysregulation. These are variably associated with multiorgan involvement, mainly of the retina, kidneys, skeleton and liver. To date, 21 causative genes have been identified, all encoding for proteins of the primary cilium or its apparatus. This is a subcellular organelle that plays key roles in development and in many cellular functions, making JS part of the expanding family of ciliopathies. There is marked clinical and genetic overlap among distinct ciliopathies, which may co-occur even within families. Such variability is likely explained by an oligogenic model of inheritance, in which mutations, rare variants and polymorphisms at distinct loci interplay to modulate the expressivity of the ciliary phenotype. PMID:23870701

Romani, Marta; Micalizzi, Alessia; Valente, Enza Maria

2013-01-01

311

Molar crown inner structural organization in Javanese Homo erectus.  

PubMed

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

Zanolli, Clément

2015-01-01

312

Relationship between bacterial contamination and alveolitis after third molar surgery.  

PubMed

The frequency of alveolitis after third molar surgery was studied in three groups of 40 patients each. One group was premedicated with penicillin V, another with scopolamine, and the third group received no premedication. The respective frequencies of alveolitis were 5, 2.5 and 32.5 % (P less than 0.01 and P less than 0.001). The aerobic flora in blood sampled from the socket before suturing was significantly reduced (P less than 0.05) in the penicillin group as compared with the controls. In alveolar blood clot sampled 48 h postoperatively, both aerobes and anaerobes were significantly diminished (P less than 0.01). The concentration of penicillin V in alveolar blood ranged from 0.8 to 9.5 mg/l. The total bacterial content in alveolar blood before suturing showed poor correlation with the development of alveolitis. Abundant growth of aerobes was found, however, in 75 % of the patients with alveolitis, but in only 47 % of those without this complication. PMID:6780476

Krekmanov, L; Hallander, H O

1980-08-01

313

Appropriate electrode placement site for electric pulp testing first molar teeth.  

PubMed

Twenty volunteers with first molars free of restorations and caries were recruited. One molar from each arch was selected, and rubber dam was applied. Seven sites on each crown were electric pulp tested 4 times with an Elements Diagnostic Unit, and lowest threshold responses were recorded. Data were analyzed with one-way analysis of variance and the Tukey test at the .01 level. The lowest response for both the maxillary and mandibular teeth was with the probe on the mesiobuccal cusp tip. Other sites showed an increase in level from the mesiobuccal cuspal surface, mesiobuccal gingival surface, and the center of the supporting cusps (palatal of maxillary molar, buccal of mandibular molar). No significant difference in responses was found between male and female subjects; however, male subjects responded at higher thresholds than female subjects on all test sites except the mesiobuccal cusp tip. The optimum site for pulp testing first molars is the mesiobuccal cusp tip. PMID:17963950

Lin, Jack; Chandler, Nicholas; Purton, David; Monteith, Brian

2007-11-01

314

The average free volume model for liquids  

E-print Network

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.

Yang Yu; Reinhard Krause-Rehberg

2014-04-02

315

Characterization of stem and progenitor cells in the dental pulp of erupted and unerupted murine molars  

PubMed Central

In the past few years there have been significant advances in the identification of putative stem cells also referred to as “mesenchymal stem cells” (MSC) in dental tissues including the dental pulp. It is thought that MSC in dental pulp share certain similarities with MSC isolated from other tissues. However, cells in dental pulp are still poorly characterized. This study focused on the characterization of progenitor and stem cells in dental pulps of erupted and unerupted mice molars. Our study showed that dental pulps from unerupted molars contain a significant number of cells expressing CD90+/CD45-, CD117+/CD45-, Sca-1+/CD45- and little if any CD45+ cells. Our in vitro functional studies showed that dental pulp cells from unerupted molars displayed extensive osteo-dentinogenic potential but were unable to differentiate into chondrocytes and adipocytes. Dental pulp from erupted molars displayed a reduced number of cells, contained higher percentage of CD45+ and lower percentage of cells expressing CD90+/CD45-, CD117+/CD45- as compared to unerupted molars. In vitro functional assays demonstrated the ability of a small fraction of cells to differentiate into odontoblasts, osteoblasts, adipocytes and chondrocytes. There was a significant reduction in the osteo-dentinogenic potential of the pulp cells derived from erupted molars compared to unerupted molars. Furthermore, the adipogenic and chondrogenic differentiation of pulp cells from erupted molars was dependent on a long induction period and infrequent. Based on these findings we propose that the dental pulp of the erupted molars contain a small population of multipotent cells, whereas the dental pulp of the unerupted molars does not contain multipotent cells but is enriched in osteo-dentinogenic progenitors engaged in the formation of coronal and radicular odontoblasts. PMID:20193787

Balic, Anamaria; Aguila, H. Leonardo; Caimano, Melissa J.; Francone, Victor P.; Mina, Mina

2010-01-01

316

Dietary Inference from Upper and Lower Molar Morphology in Platyrrhine Primates  

PubMed Central

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. PMID:25738266

Allen, Kari L.; Cooke, Siobhán B.; Gonzales, Lauren A.; Kay, Richard F.

2015-01-01

317

Partial tooth gear bearings  

NASA Technical Reports Server (NTRS)

A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

Vranish, John M. (Inventor)

2010-01-01

318

Third molar surgery: the patient's and the clinician's perspective  

PubMed Central

Background In this report, the problems of third molar surgery have been reviewed from the perspective of both patient and clinician; additionally an overall analysis of preoperative imaging investigations was carried out. Specifically, three main areas of interest were investigated: the prediction of surgical difficulty and potential complications; the assessment of stress and anxiety and finally the assessment of postoperative complications and the surgeon's experience. Findings In the first study, the prediction of surgical difficulty and potential injury to the inferior alveolar nerve was assessed. This was achieved by examining the patient's orthopantomograms and by using the Pederson Difficulty Index (PDI). Several radiological signs were identified and a classification tree was created to help predict the incidence of such event. In the second study, a prospective assessment addressing the patient's stress and anxiety pre-, intra- and postoperatively was employed. Midazolam was the active drug used against placebo. Objective and subjective parameters were assessed, including measuring the cortisol level in saliva. Midazolam was found to significantly reduce anxiety levels and salivary cortisol was identified as an accurate anxiety marker. In the third study, postoperative complications and the surgeon's experience were examined. Few patients in this study suffered permanent nerve dysfunction. Junior surgeons reported a higher complication rate particularly in trismus, alveolar osteitis, infection and paraesthesia over the distributions of the inferior alveolar and lingual nerves. In apparent contrast, senior surgeons reported higher incidence of postoperative bleeding. Discussion These studies if well employed can lead to favourable alteration in patient management and might have a positive impact on future healthcare service. PMID:19852848

Jerjes, Waseem; Upile, Tahwinder; Kafas, Panagiotis; Abbas, Syedda; Rob, Jubli; McCarthy, Eileen; McCarthy, Peter; Hopper, Colin

2009-01-01

319

Sure success partial search  

E-print Network

Partial search has been proposed recently for finding the target block containing a target element with fewer queries than the full Grover search algorithm which can locate the target precisely. Since such partial searches will likely be used as subroutines for larger algorithms their success rate is important. We propose a partial search algorithm which achieves success with unit probability.

Byung-Soo Choi; Thomas A. Walker; Samuel L. Braunstein

2006-03-15

320

Triplet pregnancy with partial hydatiform mole.  

PubMed

Triplet pregnancy with a coexisting mole is extremely rare. A 26 years old primigravida with multiple gestation and severe pre-eclampsia at 32 weeks gestation was brought to Sri Ramachandra University casualty. In view of abnormal Doppler study with discordant twins emergency lower segment caesarean section was done six days later. Part of the placenta showed molar changes. Histopathology confirmed partial mole. Patient received three cycles of methotrexate in view of rising titres of betahCG. Three months after delivery both babies are alive and well and betahCG for the mother became normal. This pregnancy continued beyond 32 weeks gestational age with both babies being alive. Hence this case is being reported to highlight its rarity. PMID:21888177

Sundari, M Siva; Agarwal, Preet; Mohan, Jayanthi

2011-02-01

321

Analysis of quantitative trait locus effects on the size and shape of mandibular molars in mice.  

PubMed Central

While >50 genes have been found to influence the development of teeth in mice, we still know very little about the genetic basis for the adaptive characteristics of teeth, such as size and shape. We applied interval mapping procedures to Procrustes size and shape data obtained from 10 morphological landmarks on the mandibular molar row of the F(2) progeny from a cross between the LG/J and SM/J strains of mice. This revealed many more QTL for molar shape (18) than for molar centroid size (3), although levels of dominance effects were comparable among QTL for size and shape. Comparisons of patterns of Procrustes additive and dominance shape effects and ordination of QTL effects by principal components analysis suggested that the effects of the shape QTL were dispersed among the three molars and thus that none of these molars represents a genetically distinct developmental structure. The results of an analysis of co-occurrence of QTL for molar shape, mandible shape, and cranial dimensions in these mice suggested that many of the QTL for molar shape may be the same as those affecting these other sets of characters, although in some cases this could be due to effects of closely linked genes. PMID:11973311

Workman, Michael Scott; Leamy, Larry J; Routman, Eric J; Cheverud, James M

2002-01-01

322

National clinical guidelines for the extraction of first permanent molars in children.  

PubMed

This article summarises recently updated guidelines produced by the Clinical Governance Directorate of the British Orthodontic Society through the Clinical Standards Committee of the Faculty of Dental Surgery, Royal College of Surgeons of England (FDSRCS) on the extraction of first permanent molars in children. The first permanent molar is susceptible to chronological enamel defects, molar-incisor hypomineralisation and caries, which may necessitate enforced extraction in the developing dentition. In the right circumstances, the extraction of these teeth can be followed by successful eruption of the second permanent molar and ultimately, third molar eruption to complete the molar dentition. For this reason, elective extraction of first permanent molars with a questionable long-term prognosis should be considered when planning enforced extractions. However, a number of factors can influence the decision-making process, including the necessity for a general anaesthetic to allow extraction, potential cooperation with restorative or orthodontic treatment and likely future preventative practice within the family. Moreover, the presence of any underlying malocclusion also needs to be evaluated within the context of extraction planning. The current available evidence has been evaluated and awarded a grade based upon those recommended by the Scottish Intercollegiate Guidelines Network. PMID:25476643

Cobourne, M T; Williams, A; Harrison, M

2014-12-01

323

on the basis of regressions of molar area versus body mass in living primates29 . The smaller  

E-print Network

on the basis of regressions of molar area versus body mass in living primates29 . The smaller sinensis from Shanghuang on the basis of molar regressions (67­ 137 g). However, several size classes seem

Packer, Alissa A.

324

Name: Seetin Question: In patients with mixed dentition, who have lost a single primary 2nd molar and require space  

E-print Network

Name: Seetin Question: In patients with mixed dentition, who have lost a single primary 2nd molar, comparison, outcome) P: Mixed dentition, lost single primary 2nd molar I: Unilateral space maintainer

Goldman, Steven A.

325

Standard molar Gibbs energy of formation of Pb 5Bi 8O 17 and PbBi 12O 19 and phase diagram of the Pb-Bi-O system  

NASA Astrophysics Data System (ADS)

Equilibrium phase fields of the ternary Pb-Bi-O system were established by long-term equilibration in the temperature range 660-840 K. Using these results, the partial phase diagram of the ternary system has been constructed. The standard molar Gibbs energy of formation of the ternary oxides, and , was determined by measuring the equilibrium oxygen partial pressures over the relevant phase fields by static manometry in conjunction with a solid oxide electrolyte-based emf cell. Further, the standard molar Gibbs energy of formation of was also measured by the manometric method. The oxide that coexists with the Pb-Bi eutectic alloy (LBE) has been experimentally confirmed as [?-PbO] ss. Using the thermochemical data measured, the compositions of Pb-Bi alloys that coexist with [?-PbO] ss and ternary oxides were derived and reported.

Ganesan, Rajesh; Gnanasekaran, T.; Srinivasa, Raman S.

2008-04-01

326

Radiographic evaluation of third molar genesis in Greek orthodontic patients  

PubMed Central

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 (?2) 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. Congenitally missing M3s in all subjects showed a significantly greater predilection for the maxilla over the mandible (19.6% and 15.5%, respectively) (Wilcoxon signed-rank test Z = ?2.404, p = 0.016). However, the distribution was found equal between the two sides of the jaws. The difference between the absent frequencies of M3s in the mandible and the maxilla was found statistically significant for the total sample (McNemar’s test, p < 0.001) and for males (p = 0.041) as well. Conclusion The study data may provide a reference for the M3 genesis in Greeks. PMID:24072974

Barka, Georgia; Marathiotis, Konstantinos; Protogerakis, Michael; Zafeiriadis, Andreas

2013-01-01

327

4-70C Propane (molar mass = 44.1 kg/kmol) poses a greater fire danger than methane (molar mass = 16 kg/kmol) since propane is heavier than air (molar mass = 29 kg/kmol), and it will settle near the floor.  

E-print Network

4-36 Ideal Gas 4-70C Propane (molar mass = 44.1 kg/kmol) poses a greater fire danger than methane (molar mass = 16 kg/kmol) since propane is heavier than air (molar mass = 29 kg/kmol), and it will settle are related to each other by R = Ru / M, where M is the molar mass of the gas. 4-73C Mass m is simply

Bahrami, Majid

328

Yeast Genomic Library Genomic DNA Sau3AI partial digestion  

E-print Network

Yeast Genomic Library Concept: Genomic DNA ­ Sau3AI partial digestion Vector DNA ­ BamHI full digestion partial Ligate and transform above products Vector Information: · use centromeric plasmid to avoid of the mcs Preparing Vector: 1) digest 3-4ug of library vector with BamHI for 2-4hrs in a total volume of 20

Odorizzi, Greg

329

Simplifying Chemical Reactor Design by using Molar Quantities Instead of Fractional Conversion.  

ERIC Educational Resources Information Center

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)

Brown, Lee F.; Falconer, John L.

1987-01-01

330

How Many Digits Should We Use in Formula or Molar Mass Calculations?  

ERIC Educational Resources Information Center

The calculations of uncertainties in the formula or molar masses of compounds are streamlined. Three rules of increasing complexity are proposed, which overestimate the uncertainty so there is little if any risk that the true values are missed.

Svensson, Christer

2004-01-01

331

Risk factors associated with prolonged recovery and delayed healing after third molar surgery  

Microsoft Academic Search

Purpose:We sought to identify the demographic, oral health, and surgical risk factors associated with prolonged recovery after third molar surgery using health-related quality of life (HRQOL) and clinical outcomes.

Ceib Phillips; Raymond P White; Daniel A Shugars; Xiaolei Zhou

2003-01-01

332

Identification of a nonsense mutation in the PAX9 gene in molar oligodontia.  

PubMed

Development of dentition is controlled by numerous genes, as has been shown by experimental animal studies and mutations that have been identified by genetic studies in man. Here we report a nonsense mutation in the PAX9 gene that is associated with molar tooth agenesis in a Finnish family. The A340T transversion creates a stop codon at lysine 114, and truncates the coded PAX9 protein at the end of the DNA-binding paired-box. All the affected members of the family were heterozygous for the mutation. The tooth agenesis phenotype involves all permanent second and third molars and most of the first molars and resembles the earlier reported phenotype that was also associated with a PAX9 mutation. The phenotype is presumably a consequence of haploinsufficiency of PAX9. In another Finnish family with molar tooth agenesis, we could not find similar sequence changes in PAX9. PMID:11781684

Nieminen, P; Arte, S; Tanner, D; Paulin, L; Alaluusua, S; Thesleff, I; Pirinen, S

2001-10-01

333

Use of the intraosseous screw for unilateral upper molar distalization and found well balanced occlusion  

PubMed Central

Background The aim of this study was to present a temporary anchorage device with intraosseous screw for unilateral molar distalization to make a space for the impacted premolar and to found well balanced occlusion in a case. Case presentation A 13-year-old male who have an impacted premolar is presented with skeletal Class I and dental Class 2 relationship. The screw was placed and immediately loaded to distalize the left upper first and second molar. The average distalization time to achieve an overcorrected Class I molar relationship was 3.6 months. There was no change in overjet, overbite, or mandibular plane angle measurements. Mild protrusion (0.5 mm) of the upper left central incisor was also recorded. Conclusion Immediately loaded intraosseous screw-supported anchorage unit was successful in achieving sufficient unilateral molar distalization without anchorage loss. This treatment procedure was an alternative treatment to the extraction therapy. PMID:17094798

Gelgor, Ibrahim Erhan; Karaman, Ali Ihya; Buyukyilmaz, Tamer

2006-01-01

334

Accidental Displacement of Third Molar into the Sublingual Space: a Case Report  

PubMed Central

ABSTRACT 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. PMID:25386232

Garcia, Robson Rodrigues; Botelho, Tessa Lucena; Franco, Ademir; Silva, Rhonan Ferreira

2014-01-01

335

Mandibular second molar with 3 mesial canals and a radix paramolaris  

PubMed Central

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. PMID:25210368

Ragavendran, N.; Bhat, Ganesh T.; Hegde, Mithra N.

2014-01-01

336

Osteomyelitis of the condyle secondary to pericoronitis of a third molar: a case and literature review.  

PubMed

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. PMID:24819410

Wang, R; Cai, Y; Zhao, Y F; Zhao, J H

2014-09-01

337

The addition of hydrogen bromide to propyne in equal molar quantities  

E-print Network

CONSTANTS, EXPERIMENTAL RESULTS. DISCUSSION, CONCLUSION. APPENDIX, REFERENCES. Page 10 16 17 22 2B 34 TABLE OF FIGURES Figure Apparatus Diagram. Infrared Spectra of Fraction Distilling Between 56 and 59 Degrees Centigrade (Reaction 58...). Page 12 Infrared Spectra (Reaction 58). Infrared Spectra (Reaction 54), of l-Bromopropene of 2-Bromopropene THE ADDITION OF HYDROGEN BROMIDE TO PROPYNE IN EQUAL MOLAR QUANTITIES INTRODUCTION In a reaction involving equal molar quantities...

Mejia, Joe Marcus

1958-01-01

338

Assessment of the lingual nerve in the third molar region using magnetic resonance imaging  

Microsoft Academic Search

Purpose: The purpose of this study was to determine the precise in situ location of the lingual nerve in the third molar region using high-resolution magnetic resonance imaging.Patients and Methods: Ten healthy volunteers (20 sides) with mandibular third molars underwent bilateral axial and coronal high-resolution magnetic resonance imaging (MRI) examinations of the posterior mandible and floor of the mouth from

Michael Miloro; Louis E Halkias; H. Wayne Slone; Donald W Chakeres

1997-01-01

339

Validity of Diagnosis of Questionable Caries Lesions in Occlusal Surfaces of Extracted Third Molars  

Microsoft Academic Search

This study was to evaluate the accuracy of visual inspection, conventional radiography, and digital radiographic methods for the detection of occlusal carious lesions in third molars from a present-day adolescent population. Seventy-eight third molars, considered clinically to be without occlusal cavities, were extracted from young soldiers. Before extraction, an intra-oral radiograph was obtained. After extraction, the teeth were examined visually

A. Wenzel; O. Fejerskov

1992-01-01

340

Changes in life quality following third molar surgery – the immediate postoperative period  

Microsoft Academic Search

Objectives This study describes patients' perceptions of changes in oral health related quality of life (OHQOL) in the early postoperative period following third molar surgery.Methods One hundred patients were enrolled in a prospective cohort study of the surgical removal of lower third molars under local anaesthetic. Two specific oral health related quality of life measures, OHIP-14 and OHQoLUKResults Both oral

M B Comfort; E C M Lo; Y Luo; C McGrath

2003-01-01

341

Biodiesel from canola oil using a 1?:?1 molar mixture of methanol and ethanol  

Microsoft Academic Search

Canola oil was transesterified using a 1 : 1 molar mixture of methanol and ethanol (M\\/E) with potassium hydroxide (KOH) catalyst. The effects of catalyst concentration (0.5-1.5 wt-%), molar ratio of M\\/E to canola oil (3 : 1 to 20 : 1) and reaction temperature (25-75 7C) on the percentage yield measured after 2.5 and 5.0 min were optimized using

Hem Joshi; Joe Toler; Bryan R. Moser; Terry Walker

2009-01-01

342

No evidence to support use of glass ionomer as a fissure sealant in primary molars  

Microsoft Academic Search

DesignRandomised controlled trial in primary care setting.Intervention508 children aged 18–30 months from high caries areas of South Wales with caries-free first primary molars were recruited to the trial after informed consent. All children (n=508) received a standard package of dental health education. Children in the test group (n=241) had their first primary molars sealed with glass ionomer. All the children

Sergio Uribe

2005-01-01

343

Volume crossover in deeply supercooled water adiabatically freezing under isobaric conditions  

NASA Astrophysics Data System (ADS)

The irreversible return of a supercooled liquid to stable thermodynamic equilibrium often begins as a fast process which adiabatically drives the system to solid-liquid coexistence. Only at a later stage will solidification proceed with the expected exchange of thermal energy with the external bath. In this paper we discuss some aspects of the adiabatic freezing of metastable water at constant pressure. In particular, we investigated the thermal behavior of the isobaric gap between the molar volume of supercooled water and that of the warmer ice-water mixture which eventually forms at equilibrium. The available experimental data at ambient pressure, extrapolated into the metastable region within the scheme provided by the reference IAPWS-95 formulation, show that water ordinarily expands upon (partially) freezing under isenthalpic conditions. However, the same scheme also suggests that, for increasing undercoolings, the volume gap is gradually reduced and eventually vanishes at a temperature close to the currently estimated homogeneous ice nucleation temperature. This behavior is contrasted with that of substances which do not display a volumetric anomaly. The effect of increasing pressures on the alleged volume crossover from an expanded to a contracted ice-water mixture is also discussed.

Aliotta, Francesco; Giaquinta, Paolo V.; Pochylski, Mikolaj; Ponterio, Rosina C.; Prestipino, Santi; Saija, Franz; Vasi, Cirino

2013-05-01

344

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models  

PubMed Central

Objective The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. Methods Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. Results No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. Conclusions 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

Nalcaci, Ruhi; Bicakci, Ali Altug; Ozturk, Firat; Babacan, Hasan

2015-01-01

345

Recommendations for Third Molar Removal: A Practice-Based Cohort Study  

PubMed Central

Objectives We investigated general dentists’ reasons for recommending removal or retention of third molars and whether patients adhered to dentists’ recommendations. Methods In a 2-year prospective cohort study (2009–2011) in the Pacific Northwest, we followed 801 patients aged 16 to 22 years from 50 general dental practices. Generalized estimating equations logistic regressions related patient and dentist characteristics to dentists’ recommendations to remove third molars and to patient adherence. Results General dentists recommended removal of 1683 third molars from 469 (59%) participants, mainly to prevent future problems (79%) or because a third molar had an unfavorable orientation or was unlikely to erupt (57%). Dentists recommended retention and monitoring of 1244 third molars from 366 (46%) participants, because it was too early to decide (73%), eruption path was favorable (39%), or space for eruption was sufficient (26%). When dentists recommended removal, 55% of participants adhered to this recommendation during follow-up, and the main reason was availability of insurance (88%). Conclusions General dentists frequently recommended removal of third molars for reasons not related to symptoms or pathology, but rather to prevent future problems. PMID:24524519

Cunha-Cruz, Joana; Rothen, Marilynn; Spiekerman, Charles; Drangsholt, Mark; McClellan, Lyle; Huang, Greg J.

2014-01-01

346

Partial Differential Equation Analysis in  

E-print Network

Partial Differential Equation Analysis in Biomedical Engineering PartialDifferentialEquationAnalysisin BiomedicalEngineering Partial Differential Equation Analysis in Biomedical Engineering Case Studies of multi-variable calculus, this introduction to computer-based partial differential equation (PDE

Gilchrist, James F.

347

Initial Clinical Experience With the Strut-Adjusted Volume Implant (SAVI) Breast Brachytherapy Device for Accelerated Partial-Breast Irradiation (APBI): First 100 Patients With More Than 1 Year of Follow-Up  

SciTech Connect

Purpose: The Strut-Adjusted Volume Implant (SAVI; Cianna Medical, Aliso Viejo, CA) is a multichannel single-entry brachytherapy device designed to allow dose modulation to minimize normal tissue dose while simultaneously maximizing target coverage. This is the first report on the initial 102 patients with nearly 2 years of median follow-up. Methods and Materials: One hundred two patients were treated at two institutions. Data were collected on eligibility and dosimetry and followed for toxicity and recurrence. Results: The median follow-up is 21 months. Overall dosimetry is outstanding (median percent of target volume receiving 90% of the prescription dose was 95.9%, volume of target receiving 150% of the prescription dose was 27.8 mL, and volume of target receiving 200% of the prescription dose was 14.0 cm{sup 3}). No devices were pulled prior to treatment completion. For patients with a skin bridge of less than 7 mm, the maximum median skin dose was 280 cGy (median percent of target volume receiving 90% of the prescription dose was 95.2%, volume of target receiving 150% of the prescription dose was 25.8 cm{sup 3} and volume of target receiving 200% of the prescription dose was 12.7 mL). For patients with both chest wall and skin of less than 7 mm, the maximum median lung dose was 205 cGy with simultaneous skin dose of 272 cGy. The rate of telangiectasia was 1.9%. Grade 1 hyperpigmentation developed in 10 patients (9.8%) and Grade 2 fibrosis in 2 patients (1.9%). There were 2 symptomatic seromas and 2 cases of asymptomatic fat necrosis (1.9%). Of the patients, 27% were not eligible for MammoSite balloon brachytherapy (Hologic, Inc., Marlborough, MA) and 5% were not eligible for any balloon brachytherapy. The recurrence rate was 1%. Conclusions: The SAVI appears to safely allow an increase in eligibility for APBI over balloon brachytherapy or three-dimensional conformal radiation, highlighting the outstanding device flexibility to maximize the target dose and minimize the normal tissue dose. The device was well tolerated by patients.

Yashar, Catheryn M., E-mail: cyashar@ucsd.edu [Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Scanderbeg, Daniel [Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Kuske, Robert [Arizona Breast Cancer Specialists, Phoenix, AZ (United States); Wallace, Anne [Department of Surgery, University of California San Diego, La Jolla, CA (United States); Zannis, Victor [Breast Care Center of the Southwest, Phoenix, AZ (United States); Blair, Sarah [Department of Surgery, University of California San Diego, La Jolla, CA (United States); Grade, Emily; Swenson, Virginia H. [Arizona Oncology Services Foundation, Phoenix, AZ (United States); Quiet, Coral [Arizona Breast Cancer Specialists, Phoenix, AZ (United States)

2011-07-01

348

Partial Derivative Visualization Gallery  

NSDL National Science Digital Library

This resource is a small gallery of demos for illustrating partial derivatives geometrically. These animations can be used by instructors in a classroom setting or by students to aid in acquiring a visualization background for partial derivatives. Two file formats, gif and QuickTime files are used for the animations which can be downloaded.

Roberts, Lila F.

2004-11-11

349

Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts  

PubMed Central

Objectives This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage. PMID:25551092

Kim, Hang-Gul

2014-01-01

350

Controlled, rapid uprighting of molars: a surprisingly simple solution the pivot arm appliance.  

PubMed

In orthodontic cases where the regional anatomy provides limited room for eruption, there is etiologically a higher occurrence of tipped/impacted second molars. Although second molar extraction with third molar replacement is a useful option, the "Pivot Arm Appliance" encourages the uprighting of the second molar as a preferred treatment. The most unique and important attribute of the "Pivot Arm Appliance" is the rotating tube. In cases of access limitation, the disto-occlusal surface of the molar presents as one area that is accessible. Other features of the "Pivot Arm Appliance" include: The position of the rotator tube delivers optimal rotational force through the pivoting action of the tube/arm complex. The "Pivot Arm Appliance" takes advantage of the efficiency and simplicity of a Class I lever system. The anatomical fulcrum being the dense cortical bone located anterior to the ascending ramus. The vertical spring system is compact, reliable and delivers gentle controlled force in rotational direction. The lingual location of the "Pivot Arm Appliance" does not hinder the function of the tongue, impinge on the soft tissue or interfere with normal masticatory function. The ease of placement of the rotator tube and subsequent insertion of the spring. It is well to note the uprighting appliance provides a very useful and practical approach to the unique problem of severely tipped second molars with limited buccal access. The "Pivot Arm Appliance" does not function only in these situations but can be used in all cases of second molar uprighting of a moderate to severe nature. PMID:12455424

Warise, T R; Galella, S A

2000-01-01

351

Cysts in Periradicular Region of Deciduous Molars in Mixed Dentition: Retrospective Study of Five Cases  

PubMed Central

ABSTRACT% The cyst in mixed dentition stage cause expansion of buccal cortex, displacement of teeth and may present as case of infection. The cyst in periradicular region of deciduous molar are of frequent occurrence. The differential diagnosis of this lesion is radicular cysts of deciduous molar: developmental or infammatory dentigerous cyst of corresponding unerupted premolar. After going through the available literature of radicular cyst of deciduous molars and dentigerous cysts of developing premolars in mixed dentition we studied the five cases of cyst in periradicular region of deciduous molars in mixed dentition retrospectively for the diagnostic dilemma of radicular cyst verses dentigerous cyst. In conclusion, we can set some criteria for the diagnosis which is particularly important for treatment and for conservation of developing premolar. How to cite this article: Manekar VS, Chavan A, Wadde K, Dewalwar V. Cysts in Periradicular Region of Deciduous Molars in Mixed Dentition: Retrospective Study of Five Cases. Int J Clin Pediatr Dent 2014;7(3):229-235. PMID:25709310

Chavan, Ankush; Wadde, Kavita; Dewalwar, Vishal

2014-01-01

352

Gender Determination Using Diagonal Measurements of Maxillary Molar and Canine Teeth in Davangere Population  

PubMed Central

Background: Mesiodistal and buccolingual measurements of the teeth have been the traditional means of determining gender which sometimes are difficult to measure. Aims and Objectives: To assess the degree of sexual dimorphism in upper permanent canines and first molars using diagonal diameters and to evaluate the applicability of diagonal measurements in sex determination. Materials and Methods: Mesiobuccal-distolingual (MBDL) and distobuccal-mesiolingual (DBML) measurements of the crown and cervix of maxillary canine and maxillary molar were taken using digital vernier callipers in 100 upper dental casts obtained from 50 males and 50 females of the age group of 17-25 y. Results: With step wise discriminant function analysis, results were statistically significant with males showing higher diagonal measurement values. The classification accuracy for males was 69% and in females was 73% with overall accuracy of 71%. Results showed that canines exhibited highest accuracy with cervical measurements being more dimorphic. MBDL measurements were found to be more reliable. Most dimorphicmeasurements included right molar cervical MBDL, left molar cervical MBDL followed by right and left molar crown MBDL. Conclusion: In cases of tooth rotations, crowding, certain fillings and attritions where traditional mesio-distal and bucco-lingual measurements are not applicable, diagonal measurements could be of help in predicting gender. PMID:25584308

Tarigoppula, Ratna Kumari V. N.; Kulkarni, Pavan G; BS, Anil

2014-01-01

353

Prevalence of cysts and tumors around the retained and unerupted third molars in the Indian population  

PubMed Central

Aim Tooth impaction is a frequent phenomena and surgical removal of these teeth are the commonest of the dental surgical procedures. The debate over the removal of asymptomatic impacted third molars still continues. The aim of this retrospective study was to determine the incidence of development of cysts and tumors around the retained and unerupted third molars in the Indian population. Material and methods 5486 impacted third molars of 4133 patients were studied through the panoramic radiographs for the presence of associated cysts and tumors. The ages of the patients ranged from 17 to 67 years, with a mean of 33.7 years. The results were evaluated using the Pearson chi-square test. P-values less than 0.05 were considered to be statistically significant. Results There were 134 cysts (2.24%) and 63 tumors (1.16%) found that were associated with impacted third molars, of which 3 were malignant (0.05%). 143 patients had symptoms such as swelling or pain due to cystic or neoplastic lesions. The remainder 54 patients had no symptoms suggestive of pathology. The most common cyst was dentigerous cyst and the most common tumor was ameloblastoma. Conclusion The results indicate that cysts and tumors do develop in a relatively small but still considerable minority of patients. The fact that a considerable number of patients had no signs or symptoms indicating pathology is certainly worth considering. Consultation should be sought from dental specialists if there are symptoms in the third molar region. PMID:25737923

Patil, Santosh; Halgatti, Vishal; Khandelwal, Suneet; Santosh, B.S.; Maheshwari, Sneha

2014-01-01

354

Partial Testing Design  

Cancer.gov

Statistical Software Partial Testing Design (Written by Stuart G. Baker) New Approach (with ROC curves): See Baker SG, Pinsky P. A proposed design and analysis for comparing digital and analog mammography: special ROC methods for cancer screening. JASA.

355

Partial Derivatives: Geometric Visualization  

NSDL National Science Digital Library

This write-pair-share activity presents Calculus III students with a worksheet containing several exercises that require them to find partial derivatives of functions of two variables. Afterwards, a series of Web-based animations are used to illustrate the surface of each function, the path of the indicated partial derivative for a specified value of the variable and the value of the derivative at each point along the path.

James Rutledge

356

Radix Entomolaris in Mandibular First Molars in Indian Population: A Review and Case Reports  

PubMed Central

Purpose. The aim of this paper is to present cases of mandibular first molars with an additional distolingual root and their management using appropriate instruments and techniques. Basic Procedures and Main Findings. Mandibular molars can sometimes present a variation called radix entomolaris, wherein the tooth has an extra root attached to its lingual aspect. This additional root may complicate the endodontic management of the tooth if it is misdiagnosed or maltreated. This paper reviews the prevalence of such cases in Indian population and reports the management of 6 such teeth. Principal Conclusions. (1) It is crucial to be familiar with variations in tooth/canal anatomy and characteristic features since such knowledge can aid location and negotiation of canals, as well as their subsequent management. (2) Accurate diagnosis and careful application of clinical endodontic skill can favorably alter the prognosis of mandibular molars with this root morphology. PMID:23125938

Attam, Kanika; Nawal, Ruchika Roongta; Utneja, Shivani; Talwar, Sangeeta

2012-01-01

357

Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.  

PubMed

The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. PMID:25256478

Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

2014-11-26

358

Accessory Central Cusp in the Maxillary Second Primary Molars: A Rare Entity among the Rare  

PubMed Central

ABSTRACT% Central accessory cusp in primary molars is an extremely rare condition which is due to abnormal proliferation and folding of inner enamel epithelium during morphodifferentiation stage of tooth development. The extension of the pulp in the cuspal area is often the reason for early involvement of pulp by the caries process. Therefore, early diagnosis and treatment planning is necessary to maintain the integrity of primary dental arch. This article reports such a case of central accessory cusps involving maxillary second primary molars. How to cite this article: Chandra B, Das M. Accessory Central Cusp in the Maxillary Second Primary Molars: A Rare Entity among the Rare. Int J Clin Pediatr Dent 2014;7(3):202-205. PMID:25709302

Das, Monalisa

2014-01-01

359

Asymmetry in mesial root number and morphology in mandibular second molars: a case report  

PubMed Central

Ambiguity in the root morphology of the mandibular second molars is quite common. The most common root canal configuration is 2 roots and 3 canals, nonetheless other possibilities may still exist. The presence of accessory roots is an interesting example of anatomic root variation. While the presence of radix entomolaris or radix paramolaris is regarded as a typical clinical finding of a three-rooted mandibular second permanent molar, the occurrence of an additional mesial root is rather uncommon and represents a possibility of deviation from the regular norms. This case report describes successful endodontic management of a three-rooted mandibular second molar presenting with an unusual accessory mesial root, which was identified with the aid of multiangled radiographs and cone-beam computed tomography imaging. This article also discusses the prevalence, etiology, morphological variations, clinical approach to diagnosis, and significance of supernumerary roots in contemporary clinical dentistry. PMID:24516829

Shetty, Shashit; Shekhar, Rhitu

2014-01-01

360

Tuning of magnetic properties in cobalt ferrite by varying Fe+2 and Co+2 molar ratios  

NASA Astrophysics Data System (ADS)

Different grades of magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized with various molar ratios of Fe+2 to Co+2 ions in the initial salt solutions by the co-precipitation method. The crystal structure and morphology of the nanoparticles are obtained from X-ray diffraction and transmission electron microscopy studies. Fourier transform infrared spectroscopy analysis exhibited the Fe-O stretching vibration ~540 cm-1, confirming the formation of metal oxide. The magnetic studies demonstrate that all of the nanoparticles are superparamagnetic at 300 K. The saturation magnetization and coercivity of the CoFe2O4 nanoparticles are affected by the molar ratios of Fe+2 to Co+2 ions. Among all the synthesized nanoparticles, the system with 75:25 molar ratio of Fe+2 to Co+2 ions with a particle size of 13 nm showed a high magnetization of 90 emu/g.

Biswal, Dipti; Peeples, Brianna N.; Peeples, Caryn; Pradhan, Aswini K.

2013-11-01

361

Early treatment of an ectopic premolar to prevent molar-premolar transposition.  

PubMed

Orthodontic treatment is planned on an individual, case-by-case basis after thoroughly considering the patient's overall facial and dental characteristics, the expected duration of treatment, costs, patient preferences, and the orthodontist's experience. This article reports the treatment of a patient with a maxillary premolar-molar transposition in the permanent dentition that was successfully managed with orthodontic treatment. A girl, aged 10 years 2 months, came for treatment with an ectopic maxillary left premolar. Radiographic analysis indicated a developing complete transposition of the maxillary left premolar. The patient was treated with extraction of the deciduous molar and surgical exposure and ligation of the premolar. Eruption was properly guided, and the correct order of the 2 teeth was restored in the arch. This challenging treatment approach is described in detail, including the mechanics used to align the ectopic premolar. Early treatment can, in many cases, prevent a molar-premolar transposition. PMID:23561418

Cannavale, Rosangela; Matarese, Giovanni; Isola, Gaetano; Grassia, Vincenzo; Perillo, Letizia

2013-04-01

362

Survival and success rate of one-piece implant inserted in molar sites  

PubMed Central

Background: Recently, the use of one-piece implants (OPI) has become more popular. Since no reports specifically focus on OPIs inserted in molar areas, a retrospective study has been performed. Materials and Methods: A series of 36 OPIs (Diamond; BIOIMPLANT, Milan, Italy) were inserted into the molar area of patients admitted at the Dental Clinic, University of Chieti, Italy, for oral rehabilitation between January and December 2010. Results: In our series survival rate (SVR) and success rate (SCR) were 91.7% and 97%, respectively. Statistical analysis demonstrated that no studied variable has an impact on survival (i.e., lost implants) as well as on clinical success (i.e., crestal bone resorption). Conclusion: OPIs are reliable devices for oral rehabilitation in the molar areas. PMID:23814575

Carinci, Francesco

2012-01-01

363

Description, Nomenclature, and Mapping of a Novel Cerebello-Renal Syndrome with the Molar Tooth Malformation  

PubMed Central

Cerebello-oculo-renal syndromes (CORSs) and Joubert syndrome (JS) are clinically and genetically heterogeneous autosomal recessive syndromes that share a complex neuroradiological malformation resembling a molar tooth on brain axial images, a condition referred to as “molar tooth on imaging” (MTI) or the “molar tooth sign.” The current literature on these syndromes is complex, with overlapping and incomplete phenotypes that complicate the selection of clinically homogeneous cases for genetic purposes. So far, only one locus (JBTS1 on 9q34) has been mapped, in two families with JS. Here, we describe a large consanguineous family with JS and nephronophthisis, representing a novel cerebello-renal phenotype. We have mapped this condition to the pericentromeric region of chromosome 11 and have named the locus “CORS2.” The acronym “CORS” is proposed for all loci associated with JS, CORSs, and related phenotypes sharing the MTI, because this neuroradiological sign seems to be the unifying feature of these clinically heterogeneous syndromes. PMID:12908130

Valente, Enza Maria; Salpietro, Damiano Carmelo; Brancati, Francesco; Bertini, Enrico; Galluccio, Tiziana; Tortorella, Gaetano; Briuglia, Silvana; Dallapiccola, Bruno

2003-01-01

364

[Realization of algorithm on finishing optimization-tool-path generation for high-speed machining molar crown].  

PubMed

Molar crown is very small and has not only thin-wall, but also complex profile, especially, the occlusal surface of each molar crown has many cusps, ridges and fossae being differently distributed. When conventional processing method is used, it is impossible to machine molar prosthesis rapidly and exactly. To enhance machining velocity and improve the surface precision of molar crown, an algorithm of entity rapid offset-based STL format is put forward. By the application of Zigzag toolpath planning and micro-machining cutter, the finishing toolpaths for high speed milling molar prosthesis are generated. In terms of Mikron UCP800 high-speed machine center, the molar all-crown made of alloy aluminum material is successfully machined. The test results show that the algorithm of tool-path generation works fast, the number of toolpaths is small, and the cutter feeds smoothly. PMID:19947500

Sun, Quanping; Chen, Xiaogang; Chen, Qianliang; Dai, Ning; Liao, Wenhe; He, Ning

2009-10-01

365

A Case of Oro-antral Communication Closed by Autotransplantation of Third Molar.  

PubMed

A number of surgical treatment modalities have been described in literature for closure of oro-antral communications. None of the methods however provide for immediate prosthetic rehabilitation of the communication site. We describe a case of oro-antral communication treated using autogenous third molar transplantation. At 18 months of follow-up, the transplanted tooth was functioning well with radiographic evidence of lamina dura and periodontal ligament. Its root-tip was still seen projecting into the maxillary sinus. This report suggests that when possible, autotransplantation of third molar can be a simple and excellent choice for closure of oro-antral communications. PMID:25848156

Nagori, Shakil Ahmed; Jose, Anson; Bhutia, Ongkila; Roychoudhury, Ajoy

2015-03-01

366

The magnitude of a human bite measured exactly at the molar Intercuspidation using FBG  

NASA Astrophysics Data System (ADS)

The aim of the study is to develop a new punctual method to determine the human bite force, between uppers and lowers first molars, at the moment of occlusion in maximum intercuspation. Fibre optic Bragg gratings are encapsulated in an acetate splint made by casting of a volunteer lower dentition. Splint sensor was positioned into the mouth to be pressured with minimal occlusal interference. The transversal pressure on the FBG was acquired at the moment of before occlusion (free), occlusion and biting. The measured forces were 12N during occlusion and 28N bite force, between right uppers and lowers first molars.

Marin, Gabriela Costa; Milczewski, Maura S.; Abe, Ilda; Lopes, Stephani C. P. S.; Camargo, Elisa S.; Kalinowski, Hypolito J.

2014-05-01

367

Maxillary first molar with 8 root canals detected by CBCT scanning: a case report.  

PubMed

Maxillary molars are prone to exhibit some of the most complex root canal configurations in endodontics. These complexities can result in diagnostic dilemmas, as well as management challenges. This case report illustrates how a cone beam computed tomography (CBCT) scan confirmed an unusual maxillary first molar with 3 root canals each in the mesiobuccal and distobuccal roots and 2 canals in the palatal root. This article illustrates how CBCT scanning and a dental operating microscope can facilitate a better understanding of complex root canal anatomies, ultimately allowing the dentist to clean, shape, and obturate root canal systems more efficiently. PMID:25734290

Almeida, Gustavo; Machado, Ricardo; Sanches Cunha, Rodrigo; Vansan, Luiz Pascoal; Neelakantan, Prasanna

2015-01-01

368

Negative urine pregnancy test in a molar pregnancy: is it possible?  

PubMed

A urine pregnancy test is commonly used to detect pregnancy and is based on finding intact ?-human chorionic gonadotrophin (hCG) molecules in the urine by an immunoassay system. However, the significantly large amount of ?-hCG in molar pregnancy may paradoxically lead to a false-negative result due to a phenomenon known as the 'high dose hook effect'. A case of molar pregnancy with negative urine pregnancy test but very high serum ?-hCG is reported. Every obstetrician should be aware of this limitation in the presence of a high index of suspicion of gestational trophoblastic disease but negative urine pregnancy test. PMID:25378114

Nigam, Aruna; Kumari, Archana; Gupta, Nidhi

2014-01-01

369

Upper molar distalization on palatal miniscrews: an easy to manage palatal appliance.  

PubMed

Upper molar distalization supported by miniscrews has become increasingly popular in the last years. A detailed clinical and lab procedure for the realization of a distalization appliance (fast back or distal jet) connected to miniscrews inserted in the anterior region of the palate is presented. A case report illustrates the use of a fast back appliance supported by miniscrews to correct the mesial shift of the molars and of the premolars as a consequence of an early loss of the maxillary deciduous canines. PMID:22583590

Huanca Ghislanzoni, Luis Tomas; Piepoli, Claudio

2012-05-01

370

Influence of the pressure on the properties of chromatographic columns III. Retention volume of thiourea, hold-up volume, and compressibility of the C18-bonded layer  

SciTech Connect

The influence of the average column pressure (ACP) on the elution volume of thiourea was measured on two RPLC columns, packed with Resolve-C{sub 18} (surface coverage 2.45 {micro} mol/m{sup 2}) and Symmetry-C{sub 18} (surface coverage 3.18 {micro} mol/m{sup 2}), and it was compared to that measured under the same conditions on an underivatized silica (Resolve). Five different methanol-water mixtures (20, 40, 60, 80 and 100% methanol, v/v) were used. Once corrected for the compressibility of the mobile phase, the data show that the elution volume of thiourea increases between 3 and 7% on the C{sub 18}-bonded columns when the ACP increases from 50 to 350 bar, depending on the methanol content of the eluent. No such increase is observed on the underivatized Resolve silica column. This increase is too large to be ascribed to the compressibility of the stationary phase (silica + C{sub 18} bonded chains) which accounts for less than 5% of the variation of the retention factor. It is shown that the reason for this effect is of thermodynamic origin, the difference between the partial molar volume of the solute in the stationary and the mobile phase, {Delta}V, controlling the retention volume of thiourea. While {Delta}V is nearly constant for all mobile phase compositions on Resolve silica (with {approx_equal} -4 mL/mol), on RPLC phases, it significantly increases with increasing methanol content, particularly above 60% methanol. It varies between -5 mL/mol and -17 mL/mol on Resolve-C{sub 18} and between -9 mL/mol and -25 mL/mol on Symmetry-C{sub 18}. The difference in surface coverage between these two RP-HPLC stationary phases increases the values of {Delta}V by about 5 mL/mol.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2005-04-01

371

Influence on the pressure on the properties of chromatographic columns III. Retention volume of thiourea, hold-up volume, and compressibility of the C18-bonded layer  

SciTech Connect

The influence of the average column pressure (ACP) on the elution volume of thiourea was measured on two RPLC columns, packed with Resolve-C{sub 18} (surface coverage 2.45 {micro} mol/m{sup 2}) and Symmetry-C{sub 18} (surface coverage 3.18 {micro} mol/m{sup 2}), and it was compared to that measured under the same conditions on an underivatized silica (Resolve). Five different methanol-water mixtures (20, 40, 60, 80 and 100% methanol, v/v) were used. Once corrected for the compressibility of the mobile phase, the data show that the elution volume of thiourea increases between 3 and 7% on the C{sub 18}-bonded columns when the ACP increases from 50 to 350 bar, depending on the methanol content of the eluent. No such increase is observed on the underivatized Resolve silica column. This increase is too large to be ascribed to the compressibility of the stationary phase (silica + C{sub 18} bonded chains) which accounts for less than 5% of the variation of the retention factor. It is shown that the reason for this effect is of thermodynamic origin, the difference between the partial molar volume of the solute in the stationary and the mobile phase, {Delta}V, controlling the retention volume of thiourea. While {Delta}V is nearly constant for all mobile phase compositions on Resolve silica (with {Delta}V {approx_equal} -4 mL/mol), on RPLC phases, it significantly increases with increasing methanol content, particularly above 60% methanol. It varies between - 5 mL/mol and - 17 mL/mol on Resolve-C{sub 18} and between - 9 mL/mol and - 25 mL/mol on Symmetry-C{sub 18}. The difference in surface coverage between these two RP-HPLC stationary phases increases the values of {Delta}V by about 5 mL/mol.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2005-05-01

372

The distribution and ultrastructure of the forming blood capillaries and the effect of apoptosis on vascularization in mouse embryonic molar mesenchyme  

PubMed Central

Vascularization is essential for organ and tissue development. Teeth develop through interactions between epithelium and mesenchyme. The developing capillaries in the enamel organ, the dental epithelial structure, occur simultaneously by mechanisms of vasculogenesis and angiogenesis at the onset of dentinogenesis. The vascular neoformation in the dental mesenchyme has been reported to start from the cap stage. However, the mechanisms of vascularization in the dental mesenchyme remain unknown. In the hope of understanding the mechanisms of the formation of dental mesenchymal vasculature, mouse lower molar germs from embryonic day (E) 13.5 to E16.5 were processed for immunostaining of CD31 and CD34, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and transmission electron microscopy (TEM). In addition, the role of apoptosis for the vascularization in dental mesenchyme was examined by in vitro culture of E14.0 lower molars in the presence of the apoptosis inhibitor (z-VAD-fmk) and a subsequent subrenal culture. Our results showed that CD31- and CD34-positive cells progressively entered the central part of the dental papilla from the peridental mesenchyme. For TEM, angioblasts, young capillaries with thick endothelium and endothelial cells containing vacuoles were observed in peripheral dental mesenchyme, suggesting vasculogenesis was taking place. The presence of lateral sprouting, cytoplasmic filopodia and transluminal bridges in the dental papilla suggested angiogenesis was also occurring. Inhibition of apoptosis delayed the angiogenic vascularization of the dental papilla. Therefore, these data demonstrated that molar mesenchyme is progressively vascularized by mechanisms of both vasculogenesis and angiogenesis and apoptosis partially contributes to the vascularization of the dental papilla. PMID:24477797

Yuan, Guohua; Zhang, Li; Yang, Guobin; Yang, Jingwen; Wan, Chunyan; Zhang, Lu; Song, Guangtai

2014-01-01

373

Slip casting of partially stabilized zirconia  

SciTech Connect

The toughness of partially-stabilized zirconia has been studied for some time. The tetragonal phase in partially stabilized ZrO2 transforms to the monoclinic phase under the influence of stress. Partially-stabilized ZrO2 has enhanced tensile strength, good wear resistance and low friction coefficient, and has found industrial applications. This article describes the use of partially-stabilized zirconia in slip casting. Lab techniques of slip casting have been reported for nonplastic materials such as Al2O3, CaF2, CaO-stabilized ZrO2 and MgO. The article discusses the variation of slip density and firing temperature and also reports the preparation of specimens of CaOstabilized ZrO2 by slip casting from ethanol-based suspensions. The preparation of Y2O3-ZrO2 compositions by slip casting from aqueous suspension is also reported. A Y2O3 partially stabilized ZrO2 powder was used as a starting material. The densities of the cast specimens were measured from the volume and weight, and those of the sintered specimens were measured by a liquid displacement technique using distilled water. The concentation of the suspension strongly affects the relative density of the cast specimen and the firing shrinkage of the sintered specimen, while the relative density of the sintered specimen is independent of the concentration of the suspension.

Taguchi, H.; Miyamoto, H.; Takahashi, Y.

1985-02-01

374

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

1999-01-01

375

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-17

376

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

2001-01-01

377

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-24

378

Oxygen partial pressure sensor  

DOEpatents

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

Dees, D.W.

1994-09-06

379

Oxygen partial pressure sensor  

DOEpatents

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

Dees, Dennis W. (Downers Grove, IL)

1994-01-01

380

Laparoscopic partial adrenalectomy  

Microsoft Academic Search

Background: Most laparoscopic adrenalectomies involve total removal of the whole adrenal gland, and reports of laparoscopic partial adrenalectomies\\u000a have been very few. The criteria for performing a laparoscopic partial adrenalectomy have not been described.\\u000a \\u000a \\u000a \\u000a \\u000a Methods: (a) Patients with functioning adrenal tumors smaller than 3 cm in diameter were selected. (b) The solitary adrenal tumors\\u000a were evaluated by preoperative thin-slice computed

T. Imai; Y. Tanaka; T. Kikumori; M. Ohiwa; N. Matsuura; T. Mase; H. Funahashi

1999-01-01

381

Characterization of Alternan, a high molar mass polysaccharide from Leuconostoc mesenteroides, by FFF-MALS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Native alternan is a high molar mass homopolymer of D-glucose produced by some strains of the bacterium Lueconostoc mesenteroides. It consists of glucose units that alternate their linkages between alpha-(1-6) and alpha-(1-3) between glucosyl units. The glucose units contained in the polysaccharid...

382

How to measure and predict the molar absorption coefficient of a protein  

Microsoft Academic Search

The molar absorption coefficient, E, of a protein is usually based on concentrations measured by dry weight, ni- trogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring E for a protein. (This method is described by Gill and von Hippel (1989, Anal Biochem 182:319- 3261 and is based on

C. Nick Pace; Felix Vajdos; Lanette Fee; Gerald Grimsley; Theronica Gray

1995-01-01

383

Endodontic management of a mandibular second molar with radix entomolaris: a case report  

PubMed Central

The presence of radix entomolaris (RE) in a mandibular first molar is a common occurrence in certain ethnic groups, but the presence of RE in a mandibular second molar is a rare occurrence. In the present case, RE was identified from preoperative radiographs and confirmed using cone-beam computed tomography (CBCT). The access cavity was modified to locate the RE. Cleaning and shaping were performed with nickel-titanium rotary instruments. Obturation was completed with gutta-percha cones using AH Plus (Dentsply Detrey GmbH) as sealer. From the CBCT axial images, the RE was determined to have a Type III curvature by the De Moor classification, Type B separate RE by the Carlsen and Alexandersen classification, and radiographically, a Type i image by the Wang classification. The presence of RE in the mandibular second molar makes it essential to anticipate and treat the distolingual root canal. This case report highlights the usefulness of CBCT for assessing RE in the mandibular second molar, which can help the clinician in making a confirmatory diagnosis and assessing the morphology of the root canal. PMID:24790927

Kandaswamy, Deivanayagam; Jayaprakash, Nachimuthu

2014-01-01

384

Endodontic management of a mandibular second molar with radix entomolaris: a case report.  

PubMed

The presence of radix entomolaris (RE) in a mandibular first molar is a common occurrence in certain ethnic groups, but the presence of RE in a mandibular second molar is a rare occurrence. In the present case, RE was identified from preoperative radiographs and confirmed using cone-beam computed tomography (CBCT). The access cavity was modified to locate the RE. Cleaning and shaping were performed with nickel-titanium rotary instruments. Obturation was completed with gutta-percha cones using AH Plus (Dentsply Detrey GmbH) as sealer. From the CBCT axial images, the RE was determined to have a Type III curvature by the De Moor classification, Type B separate RE by the Carlsen and Alexandersen classification, and radiographically, a Type i image by the Wang classification. The presence of RE in the mandibular second molar makes it essential to anticipate and treat the distolingual root canal. This case report highlights the usefulness of CBCT for assessing RE in the mandibular second molar, which can help the clinician in making a confirmatory diagnosis and assessing the morphology of the root canal. PMID:24790927

Hannah, Rosaline; Kandaswamy, Deivanayagam; Jayaprakash, Nachimuthu

2014-05-01

385

Is Overweight a Risk Factor for Adverse Events during Removal of Impacted Lower Third Molars?  

PubMed Central

Being overweight is recognised as a significant risk factor for several morbidities; however, the experience of the dentistry faculties focusing on this population is still low. The aim of the present study was to determine the occurrence of adverse events during removal of impacted lower third molars in overweight patients. A prospective cohort study was carried out involving overweight patients subjected to surgical removal of impacted lower third molar as part of a line of research on third molar surgery. Predictor variables indicative of the occurrence of adverse events during surgery were classified by their demographic, clinical, radiographic, and surgical aspects. Descriptive and bivariate statistics were computed. In total, 140 patients fulfilled the eligibility criteria, and 280 surgeries were performed. Patients' mean age was 25.1 ± 2.2 years, and the proportion of women to men was 3?:?1. Eight different adverse events during surgery were recorded. These events occurred in approximately 29.3% of cases and were significantly associated with predictor variables (P < 0.05). Excess weight is recognised as a risk factor for the high rate of adverse events in impacted third molar surgery. The study suggests that overweight patients are highly likely to experience morbidities. PMID:25548786

de Carvalho, Ricardo Wathson Feitosa; do Egito Vasconcelos, Belmiro Cavalcanti

2014-01-01

386

Molar Mass Profiling of Synthetic Polymers by Free-Solution Capillary Electrophoresis of  

E-print Network

Molar Mass Profiling of Synthetic Polymers by Free-Solution Capillary Electrophoresis of DNA of the DNA-polymer conju- gates as a function of the size of the uncharged PEG tail. This provides a profile) (PEG)), based upon single-monomer resolution of DNA-polymer conjugates by free-solution capillary

Barron, Annelise E.

387

Post-natal Effect of Overexpressed DKK1 on Mandibular Molar Formation  

PubMed Central

Dickkopf-related protein 1 (DKK1) is a potent inhibitor of Wnt/?-catenin signaling. Dkk1-null mutant embryos display severe defects in head induction. Conversely, targeted expression of Dkk1 in dental epithelial cells leads to the formation of dysfunctional enamel knots and subsequent tooth defects during embryonic development. However, its role in post-natal dentinogenesis is largely unknown. To address this issue, we studied the role of DKK1 in post-natal dentin development using 2.3-kb Col1a1-Dkk1 transgenic mice, with the following key findings: (1) The Dkk1 transgene was highly expressed in pulp and odontoblast cells during post-natal developmental stages; (2) the 1st molar displayed short roots, an enlarged pulp/root canal region, and a decrease in the dentin formation rate; (3) a small malformed second molar and an absent third molar; (4) an increase of immature odontoblasts, few mature odontoblasts, and sharply reduced dentinal tubules; and (5) a dramatic change in Osx and nestin expression. We propose that DKK1 controls post-natal mandibular molar dentin formation either directly or indirectly via the inhibition of Wnt signaling at the following aspects: (i) post-natal dentin formation, (ii) formation and/or maintenance of the dentin tubular system, (iii) mineralization of the dentin, and (iv) regulation of molecules such as Osx and nestin. PMID:21917600

Han, X.L.; Liu, M.; Voisey, A.; Ren, Y.S.; Kurimoto, P.; Gao, T.; Tefera, L.; Dechow, P.; Ke, H.Z.; Feng, J.Q.

2011-01-01

388

Femto-Molar Sensitive Field Effect Transistor Biosensors Based on Silicon Nanowires and  

E-print Network

Femto-Molar Sensitive Field Effect Transistor Biosensors Based on Silicon Nanowires and Antibodies-- This article presents electrically-based sensors made of high quality silicon nanowire field effect transistors characterizing the early stage of the diseases. Devices like field-effect transistors (FETs) can be suitable can

Dalang, Robert C.

389

Ovulation stimulation after treatment for a molar pregnancy for or against?  

PubMed

The case of a 29-year-old patient who underwent invitro fertilization due to secondary sterility, after a spontaneous but molar pregnancy, is described. Afterwards there was no spontaneous conception for five years. With the couple's consent, we decided to perform in vitro fertilization, i.e., ovulation induction and the ICSI (intracytoplasmic sperm injection) method. PMID:19317269

Gojnic, M; Dugalic, V; Brankovic, M; Pervulov, M; Vasiljevic, B; Fazlagic, A

2009-01-01

390

Distal movement of mandibular molars in adult patients with the skeletal anchorage system  

Microsoft Academic Search

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units. Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become

Junji Sugawara; Takayoshi Daimaruya; Mikako Umemori; Hiroshi Nagasaka; Ichiro Takahashi; Hiroshi Kawamura; Hideo Mitani

2004-01-01

391

Critical flux in NF of high molar mass polysaccharides and effluents from the paper industry  

Microsoft Academic Search

High molar mass polysaccharides (locust bean gum and karaya gum) and effluents from a mechanical pulp mill and a paper mill were nanofiltered with commercially available nanofiltration (NF) membranes. The effect of the filtration conditions on the flux (critical flux), retention, and the fouling of the membranes was studied. The experiments were conducted by increasing and decreasing the pressure and

M Mänttäri; M Nyström

2000-01-01

392

Molar Functional Relations and Clinical Behavior Analysis: Implications for Assessment and Treatment  

ERIC Educational Resources Information Center

The experimental analysis of behavior has identified several molar functional relations that are highly relevant to clinical behavior analysis. These include matching, discounting, momentum, and variability. Matching provides a broader analysis of how multiple sources of reinforcement influence how individuals choose to allocate their time and…

Waltz, Thomas J.; Follette, William C.

2009-01-01

393

Molar Tooth Sign in Joubert Syndrome: Clinical, Radiologic, and Pathologic Significance  

Microsoft Academic Search

Joubert syndrome is a rare autosomal-recessive condition characterized by early hyperpnea and apnea, developmental delay, and truncal ataxia. We previously described key ocular motor signs in Joubert syndrome and the molar tooth sign resulting from dysplasia of the isthmic segment of the brain stem, superior cerebellar peduncles, and vermis. In this study, we obtained clinical and developmental data in 61

Bernard L. Maria; Ronald G. Quisling; Louis C. Rosainz; Anthony T. Yachnis; Jill Gitten; Duane Dede; Eileen Fennell

1999-01-01

394

Closing anterior open bites by intruding molars with titanium miniplate anchorage  

Microsoft Academic Search

The intent of this study was threefold: (1) to validate true intrusion of molars in adults, (2) to test the stability of miniplates as anchorage for intruding posterior teeth in the maxilla, and (3) to record the skeletal and dental changes of open-bite closure. Four adult patients who had anterior open-bite malocclusions were selected to undergo posterior intrusion with miniplate

Keith H. Sherwood; James G. Burch; William J. Thompson

2002-01-01

395

Validation of common classification systems for assessing the mineralization of third molars  

Microsoft Academic Search

One major criterion for dental age estimation is the evaluation of third molar mineralization. There are various methods for evaluating tooth mineralization based on classification by stages. The aim of the present work is to assess the validity of the common classification systems. To this end, we analyzed 420 conventional orthopantomograms of German females aged 12–25 years old. The mineralization

Andreas Olze; Dominique Bilang; Sven Schmidt; Klaus-Dieter Wernecke; Gunther Geserick; Andreas Schmeling

2005-01-01

396

Sensory impairment of the lingual and inferior alveolar nerves following removal of impacted mandibular third molars  

Microsoft Academic Search

Abstract.In a prospective study 1106 impacted mandibular third molars were removed from 687 patients. Clinical, radiographic, and surgical factors were recorded. Postoperatively, we examined the modalities of common sensation in order to assess sensory deficit. The patients were followed up, until complete restitution occurred, or, if the sensibility failed to recover, for at least 6 months. A total of 3.6%

D. Gülicher; K. L. Gerlach

2001-01-01

397

Concentration dependence of specific and molar refractions of KOH + {ethanol-water} mixtures  

NASA Astrophysics Data System (ADS)

Densities and refractive indices of KOH solutions of three different concentrations in solutions of ethanol in water with different concentrations were measured at 303.15 K. From densities and refractive indices the specific refractions and molar refractions were estimated and interpreted in terms of molecular interactions. Concentration dependence of ( n {/D 2} - 1)/( n {/D 2} + 2) has been studied.

Deosarkar, S. D.

2013-08-01

398

40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.  

Code of Federal Regulations, 2014 CFR

...flow rates from various flow meters. After you calibrate a flow meter according to § 1065.640, use the calculations described in this section to calculate flow during an emission test...mix-cal = molar mass of gas mixture used during...

2014-07-01

399

Temporomandibular joint loading generated during bilateral static bites at molars and premolars  

Microsoft Academic Search

The aim of this study was to investigate the features of the loading vectors of the temporomandibular joint (TMJ) generated during bilateral static bites at the molars and at the premolars, and to determine the major factors affecting the difference between the two loading vectors. We computed the subjects’ estimated and theoretical minimum TMJ loadings under the two different bite

Makoto Abe; Raul U. Medina-Martinez; Ken-ichi Itoh; Shoji Kohno

2006-01-01

400

[Dental health of first molars among Westphalian immigrants and German students].  

PubMed

The aim of this study was to assess the health status of the occlusal surface on the first molars of Westphalian students, of whom 41.0% were immigrants. The prevalence and retention of fissure sealants (FS) and caries experience was scored for 161 students aged 8 and 10 years. Logistic regression analysis was used to predict the influence of sex, ethnicity, and retention of FS on the occlusal caries risk of the first molars. There was no difference in caries prevalence and experience in 8-year-old German students and immigrants (5.6%/10.5%; 0.07 DMFT/0.21 DMFT), both parameters were significantly higher in 10-year-old immigrants than in German students (25.5%/9.5%; 0.55 DMFT/0.11 DMFT). The prevalence and number of molars with FS was not different between German students and immigrants at 8 years (39.1%, 1.28 FS; 33.8%, 0.94 FS) and at 10 years of age (47.4%, 1.68 FS; 39.4%, 1.17 FS). The occlusal caries risk of first molars without FS was significantly higher in 8-year-old immigrants than in German students (OR 4.62). FS should be used more frequently in daily dental practice. To improve the quality of FS, stricter implementation of guideline-based standards is required. PMID:24297452

Heinrich-Weltzien, R; Walther, M; Goddon, I; Kühnisch, J

2014-01-01

401

Sensibility and taste alterations after impacted lower third molar extractions. A prospective cohort study  

PubMed Central

Objectives: To determine the incidence, severity and duration of lingual tactile and gustatory function impairments after lower third molar removal. Study Design: Prospective cohort study with intra-subject measures of 16 patients undergoing lower third molar extractions. Sensibility and gustatory functions were evaluated in each subject preoperatively, one week and one month after the extraction, using Semmes-Weinstein monofilaments and 5 different concentrations of NaCl, respectively. Additionally, all patients filled a questionnaire to assess subjective perceptions. Results: Although patients did not perceive any sensibility impairments, a statistically significant decrease was detected when Semmes-Weinstein monofilaments. This alteration was present at one week after the surgical procedure and fully recovered one month after the extraction. There were no variations regarding the gustatory function. Conclusions: Lower third molar removal under local anesthesia may cause light lingual sensibility impairment. Most of these alterations remain undetected to patients. These lingual nerve injuries are present one week after the extraction and recover one month after surgery. The taste seems to remain unaffected after these procedures. Key words:Lingual nerve, third molar, nerve injury, paresthesia, surgical extraction PMID:22322520

Ridaura-Ruiz, Lourdes; Valmaseda-Castellón, Eduard; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

2012-01-01

402

Radix mesiolingualis and radix distolingualis in a collection of permanent maxillary molars.  

PubMed

Two lingual root structures are occasionally found on human permanent maxillary molars. One of these is the normal lingual root, which is always present, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis (RML)) or distolingually (radix distolingualis (RDL)). The available literature refers only to the existence and location of RML and RDL Very small materials have, quite simply, hitherto precluded a more detailed description of these roots. The large collection of extracted teeth at the School of Dentistry in Copenhagen now includes a non-random subcollection of 145 permanent maxillary molars, the root complex of which contains 2 lingual root structures. Based on this material it was possible to undertake a modern, systematic analysis of the macromorphological variation of RMLs and RDLs. In this study, which was mainly non-metric, criteria for the identification of RML and RDL were established. The analysis also showed that the lingual supernumerary roots were only rarely found on the first molar, but with increasing frequency on the second and third molars. Both separate and non-separate RML and RDL were observed. In the material, degrees of separation greater than 0.9 were registered, degrees of divergence up to approximately 45 degrees, an apical bend of approximately 90 degrees, and extreme apical slenderness. Even though the supernumerary roots described here do not occur very often, knowing about them is nevertheless clinically relevant in for example endodontic and surgical contexts. PMID:11144874

Carlsen, O; Alexandersen, V

2000-10-01

403

Effect of Sensory Denervation on the Response of Rat Molar Pulp to Exposure Injury  

Microsoft Academic Search

Sensory nerve fibers that contain calcitonin gene-related peptide (CGRP) have been shown previously to sprout into inflamed tissue surrounding sites of pulpal injury. The sprouting fibers contain increased CGRP immunoreactivity (IR), and neuropeptide levels increase in the surrounding pulp. We compared denervated and innervated first mandibular molars of rats to determine whether the absence of sensory nerve fibers affected tissue

M. R. Byers; P. E. Taylor

1993-01-01

404

Original article Effects of pH and Ca/P molar ratio  

E-print Network

phosphates from dairy co-products. pH is also important in the fouling phenomena of membranes and heatOriginal article Effects of pH and Ca/P molar ratio on the quantity and crystalline structure in dairy industry depend on the physico-chemical conditions, particularly, pH and mineral composition

Paris-Sud XI, Université de

405

Post-natal effect of overexpressed DKK1 on mandibular molar formation.  

PubMed

Dickkopf-related protein 1 (DKK1) is a potent inhibitor of Wnt/?-catenin signaling. Dkk1-null mutant embryos display severe defects in head induction. Conversely, targeted expression of Dkk1 in dental epithelial cells leads to the formation of dysfunctional enamel knots and subsequent tooth defects during embryonic development. However, its role in post-natal dentinogenesis is largely unknown. To address this issue, we studied the role of DKK1 in post-natal dentin development using 2.3-kb Col1a1-Dkk1 transgenic mice, with the following key findings: (1) The Dkk1 transgene was highly expressed in pulp and odontoblast cells during post-natal developmental stages; (2) the 1(st) molar displayed short roots, an enlarged pulp/root canal region, and a decrease in the dentin formation rate; (3) a small malformed second molar and an absent third molar; (4) an increase of immature odontoblasts, few mature odontoblasts, and sharply reduced dentinal tubules; and (5) a dramatic change in Osx and nestin expression. We propose that DKK1 controls post-natal mandibular molar dentin formation either directly or indirectly via the inhibition of Wnt signaling at the following aspects: (i) post-natal dentin formation, (ii) formation and/or maintenance of the dentin tubular system, (iii) mineralization of the dentin, and (iv) regulation of molecules such as Osx and nestin. PMID:21917600

Han, X L; Liu, M; Voisey, A; Ren, Y S; Kurimoto, P; Gao, T; Tefera, L; Dechow, P; Ke, H Z; Feng, J Q

2011-11-01

406

Regaining leeway space and anterior crossbite correction with a modified maxillary molar distalizing appliance.  

PubMed

During the mixed dentition stage, adolescents experience rapid dental and skeletal development. Unfortunately, many of them do not visit the orthodontist early enough and miss out on the opportunity to take advantage of preventive and interceptive orthodontic treatment. This article describes the management of regaining leeway space and correcting anterior crossbite using a modified maxillary molar distalizing appliance. PMID:23855181

Park, J H; Tai, K; Ikeda, M; Kanao, A

2013-01-01

407

A method for studying optical anisotropy of polymers as a function of molar mass.  

PubMed

Optical properties of polymers are extremely important in many end-use applications, as is the ability of anisotropic polymers to depolarize incident radiation. To date, most light-scattering studies of the optical anisotropy of macromolecules have dealt with the bulk state or measured ensemble properties of dilute solutions. Here, we introduce a method to determine the optical anisotropy as a continuous function of molar mass. By direct, on-line coupling of size-exclusion chromatography and depolarization multiangle light scattering (SEC/D-MALS), molar mass averages, polydispersities, molar mass distributions, and the distribution of the optical anisotropy as a function of molar mass may all be determined. To quantify the anisotropy, it has been expressed in terms of the Cabannes factor, thus permitting the Rayleigh ratio necessary for light-scattering calculations to be corrected for anisotropy. The effects of tacticity, heavy atom substitution on the main chain, and chain helicity on the depolarization behavior of polymers have been studied using atactic and isotactic PMMA; atactic and brominated PS; and the semiflexible polypeptide PBLG, which maintains an extended structure in solution. An introduction to the theory of SEC/D-MALS is given. PMID:12141659

Striegel, André M

2002-07-01

408

Use of the intraosseous screw for unilateral upper molar distalization and found well balanced occlusion  

Microsoft Academic Search

BACKGROUND: The aim of this study was to present a temporary anchorage device with intraosseous screw for unilateral molar distalization to make a space for the impacted premolar and to found well balanced occlusion in a case. CASE PRESENTATION: A 13-year-old male who have an impacted premolar is presented with skeletal Class I and dental Class 2 relationship. The screw

Ibrahim Erhan Gelgor; Ali Ihya Karaman; Tamer Buyukyilmaz

2006-01-01

409

Hemisection: A conservative management of periodontally involved molar tooth in a young patient  

PubMed Central

Hemisection is sectioning of multi-rooted teeth with its crown portion, with the loss of periodontal attachment and is performed to retain the original tooth structure and attain the fixed prosthodontic prosthesis. We describe hemisection of a mandibular molar tooth followed by adequate restoration in a young patient.

Babaji, Prashant; Sihag, Tarun; Chaurasia, Vishwajit Rampratap; Senthilnathan, Sivaramalingam

2015-01-01

410

Secular trend of earlier onset and decelerated development of third molars: Evidence from Croatia.  

PubMed

The purpose of this study was to evaluate the influence of the secular trend on development of third molars in 30 years period in Littoral region of Croatia. A total of 1103 panoramic radiographs of subjects aged from 6 to 18 years were analysed. First group comprised 531 panoramic radiographs (258 girls) taken from year period 1977 till 1979 and second group 572 radiographs (325 girls) taken from year period 2007 till 2009. Demirjian's method was used to determine the developmental stage of third molars. A secular trend in 30 years period was observed as earlier onset of third molars development in boys (6 months on average maxillary and 11 months mandibular) and girls (6 months for maxillary and 4 months for mandibular). Now-a-days, an increase in mineralisation for one Demirjian stage occurs at a slower pace of 5.2 months in boys and 3.4 in girls in maxilla and 2.3 or 2 months in mandible for boys and girls, respectively. The study showed a secular trend present as earlier onset but decelerated development of third molars in both genders and both jaws. PMID:25710780

Sasso, Anja; Legovic, Mario; Mady Maricic, Barbara; Pavlic, Andrej; Spalj, Stjepan

2015-04-01

411

Complication rates in patients using absorbable collagen sponges in third molar extraction sockets: a retrospective study  

PubMed Central

Objectives The purpose of this study is to retrospectively evaluate the postoperative complication rates for absorbable type-I collagen sponge (Ateloplug; Bioland) use in third molar extraction. Materials and Methods From January to August 2013, 2,697 total patients undergoing third molar extraction and type-I collagen sponge application in the Department of Oral and Maxillofacial Surgery at Yonsei University Dental Hospital (1,163 patients) and Dong-A University Hospital (1,534 patients) were evaluated in a retrospective study using their operation and medical records. Results A total of 3,869 third molars in 2,697 patients were extracted and the extraction sockets packed with type-I collagen sponges to prevent postoperative complications. As a result, the overall complication rate was 4.52%, with 3.00% experiencing surgical site infection (SSI), 1.14% showing alveolar osteitis, and 0.39% experiencing hematoma. Of the total number of complications, SSI accounted for more than a half at 66.29%. Conclusion Compared to previous studies, this study showed a relatively low incidence of complications. The use of type-I collagen sponges is recommended for the prevention of complications after third molar extraction. PMID:25741465

Cho, Hoon; Jung, Hwi-Dong; Kim, Bok-Joo; Kim, Chul-Hoon

2015-01-01

412

Selenium:mercury molar ratios in bullfrog and leopard frog tadpoles from the northeastern United States.  

PubMed

Vertebrates experience adverse effects from methylmercury, largely obtained through their food. Selenium has the potential to reduce the toxic effects of methylmercury (and vice versa). In this paper, we examine the selenium:mercury molar ratios in tadpoles (Lithobates sphenocephalus, Lithobates catesbeianus (formerly Rana), and a newly documented leopard frog species currently referred to as R. sp. nov.) and fully formed leopard frog metamorphs. There were no significant differences in metal levels between the two leopard frog species, and data were therefore combined. Selenium:mercury molar ratios varied from 19 to 38 for bullfrog tadpoles, from 16 to 330 for leopard frog tadpoles, and from 7 to 17 for leopard frog metamorphs. Leopard frog tadpoles with less than 45 days exposure to field conditions had significantly higher molar ratios than other tadpoles and leopard frog metamorphs. There were significant locational differences for the molar ratios of bullfrogs, and leopard frog tadpoles with more than 45 days of field exposure. At the sites where we were able to sample both leopard frog tadpoles and leopard frog metamorphs, there were significant differences between the two distinct life stages. Most of the variation in the ratio was accounted for by selenium levels, field sites, and exposure period. PMID:24585386

Burger, Joanna; Feinberg, Jeremy; Jeitner, Christian; Gochfeld, Michael; Donio, Mark; Pittfield, Taryn

2014-06-01

413

STABILITY OF INGESTED METHYCELLULOSE IN THE RAT DETERMINED BY POLYMER MOLAR MASS MEASUREMENTS BY LIGHT SCATTERING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Methylcellulose (MC) is ingested by humans in food and pharmaceutical formulations. The functional properties of MC like those of other linear polymers depends primarily on polymer length or molar mass for largely linear polymers. Although many studies in animals and humans have shown complete exc...

414

A COMPARISON OF LIME AND ORANGE PECTIN BY HPSGC WITH MOLAR MASS AND VISCOSITY DETECTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pectin was acid extracted from lime albedo by microwave heating under pressure. Extraction times ranged from 1 to 10 minutes. Solubilized pectin was characterized for molar mass (M), rms radius of gyration (Rg) and intrinsic viscosity (IV) by HPSEC with online light scattering and viscosity detect...

415

Biodiesel from Canola Oil using a 1:1 Molar Mixture of Methanol and Ethanol  

Technology Transfer Automated Retrieval System (TEKTRAN)

Canola oil was transesterified using an equimolar mixture of ethanol and methanol with potassium hydroxide (KOH) catalyst. Effect of catalyst concentration (0.5 to 1.5% wt/wt), molar ratio of equimolar mixture of ethanol and methanol (EMEM) to canola oil (3:1 to 12:1) and reaction temperature (25 t...

416

Brief Communication: Dental Development and Enamel Thickness in the Lakonis Neanderthal Molar  

E-print Network

Brief Communication: Dental Development and Enamel Thickness in the Lakonis Neanderthal Molar T affinities between modern human and Neanderthal dental remains continue to be a subject of debate as well as a Neanderthal based on the presence of an anterior fovea and mid-trigo- nid crest. Crown formation

Smith, Tanya M.

417

Modifications in Canal Anatomy of Curved Canals of Mandibular First Molars by two Glide Path Instruments using CBCT  

PubMed Central

Background: The creation of glide path reduces the risk of instrument breakage. Glide path is created before using NiTi rotary instrumentation Aim: This study compared the changes in the root canal anatomy after creation of glide path using Path Files (PF) and V Glide Path 2 (VGP2) using Cone Beam Computed Tomography (CBCT). Materials and Methods: Hundred extracted mandibular first molars with curved mesial roots, curvature angles ranging within 20-30 degrees were assigned into two groups (n = 50 each). Glide path was prepared using PF (Group I) and VGP2 (Group II). CBCT images were obtained before and after instrumentation. The technical outcomes were compared at 0, 1, 2, 3, 5 and 7mm intervals. The data was analyzed using t-test and Chi-square test. Result: There was a statistical difference between the root canal curvatures and working time between the two groups (p < 0.05). Canals transported towards the distal side in Group II but there was a slight mesial transportation in Group I at 0mm. Group I exhibited a better centric ability except at 1mm interval (p > 0.05). The changes in the volume were statistically significant only at 2mm interval (p < 0.05). The difference in the cross sectional area was not statistically significant at any interval (p > 0.05). Conclusion: Within the limits of this study the rotary Nickel Titanium Path Files appeared to be suitable instruments for safe and easy creation of glide path. PMID:25584304

Manchanda, Nayasha

2014-01-01

418

Mineralization during matrix-vesicle-mediated mantle dentine formation in molars of albino rats: a microanalytical and ultrastructural study.  

PubMed

The purpose of this study was to elucidate the mineralization process of mantle dentine by ultrastructural and element-analytical investigation of matrix vesicles and successive stages. Upper second molars of albino rats were cryofixed and embedded in resin after freeze drying. Semithin dry sections were prepared for analyzing the calcium and phosphorus concentrations in the mineralized matrix vesicles or noduli, larger mineralized islands, and the mantle dentine. For ultrastructural studies, it was necessary to reduce section contact with hydrous fluids to a minimum in order to avoid preparation artifacts. The first mineral deposits were recognized as dot-like formations both in the interior of matrix vesicles and in association with the inner vesicle membrane. This indicated the existence of mineral nucleating sites located both at the inner membrane and at calcium-phosphate-binding macromolecules in the interior of the matrix vesicles. A significantly higher mineral content was found in mineralized matrix vesicles than in the mineralized extravesicular regions of the mineralized islands, suggesting the existence of a rapidly and densely mineralized matrix in the matrix vesicles. A significant increase in mineral content per volume proceeding from the mineralized islands to mantle dentine suggested a further increase in the density of mineral. PMID:8625389

Stratmann, U; Schaarschmidt, K; Wiesmann, H P; Plate, U; Höhling, H J

1996-05-01

419

Pain Control Following Impacted Third Molar Surgery with Bupivacaine Irrigation of Tooth Socket: A Prospective Study  

PubMed Central

Background and aims The surgical removal of the lower third molars is a procedure generally followed by side effects such as postoperative pain. The aim of this study was to evaluate the efficacy of socket irrigation with an anesthetic solution in relieving pain following impacted third molar surgery. Materials and methods Thirty-four patients (17 males and 17 females), aged 18-24 years, with bilateral impacted lower third molars were selected. Both third molars were extracted in one surgical session. Tooth sockets in each patient were rinsed randomly either with 4 mL of 0.5% bupivacaine hydrochloride plain (without vasoconstrictor) anesthetic solu-tion or 4 mL of normal saline, used as control. The patients were instructed not to use analgesics as long as possible, and if not, they were instructed to use an analgesic, and record the time. Pain severity was assessed using a visual analogue pain scale (VAPS) at 1-, 6-, 12-, and 24-hour intervals post-operatively. Data were analyzed using Pearson’s chi-square test and P <0.05 was considered statistically significant. Results Post-operative pain difference between the two groups was statistically significant at 1-, 6-, 12- and 24-hour post-operative intervals (P <0.05). Post-operative pain increased in both groups to a maximum 12 hours after surgery with signif-icant improvements after that. Conclusion Based on the results, the irrigation of surgery site with bupivacaine after third molar surgery significantly reduces post-operative pain. PMID:23346335

Khorshidi Khiavi, Reza; Pourallahverdi, Maghsood; Pourallahverdi, Ayda; Ghorani Khiavi, Saadat; Ghertasi Oskouei, Sina; Mokhtari, Hadi

2010-01-01

420

Partially reflecting sheet arrays  

Microsoft Academic Search

Multiple reflections of electromagnetic waves between two planes are studied, and the increase in directivity that results by placing a partially reflecting sheet in front of an antenna with a reflecting screen is investigated at a wavelength of 3.2 cm. The construction and performance of various models of such arrays is discussed. Thus, for example, a \\

G. V. Trentini

1956-01-01

421

PARTIALLY SUPERFLUOUS OBSERVATIONS  

Microsoft Academic Search

Necessary and sufficient conditions are established for the second subsample to be partially redundant given the first subsample for the best linear unbiased estimator of a subset of the coefficient vector of a general linear regression model.We thank the Co-editor for his very helpful comments on an earlier draft.

Hailong Qian; Yongge Tian

2006-01-01

422

Swallowed partial dentures  

PubMed Central

Swallowed or inhaled partial dentures can present a diagnostic challenge. Three new cases are described, one of them near-fatal because of vascular erosion and haemorrhage. The published work points to the importance of good design and proper maintenance. The key to early recognition is awareness of the hazard by denture-wearers, carers and clinicians. PMID:14749401

Hashmi, Syed; Walter, John; Smith, Wendy; Latis, Sergios

2004-01-01

423

Partial gravity habitat study  

NASA Technical Reports Server (NTRS)

The purpose of this study is to investigate comprehensive design requirements associated with designing habitats for humans in a partial gravity environment, then to apply them to a lunar base design. Other potential sites for application include planetary surfaces such as Mars, variable-gravity research facilities, and a rotating spacecraft. Design requirements for partial gravity environments include locomotion changes in less than normal earth gravity; facility design issues, such as interior configuration, module diameter, and geometry; and volumetric requirements based on the previous as well as psychological issues involved in prolonged isolation. For application to a lunar base, it is necessary to study the exterior architecture and configuration to insure optimum circulation patterns while providing dual egress; radiation protection issues are addressed to provide a safe and healthy environment for the crew; and finally, the overall site is studied to locate all associated facilities in context with the habitat. Mission planning is not the purpose of this study; therefore, a Lockheed scenario is used as an outline for the lunar base application, which is then modified to meet the project needs. The goal of this report is to formulate facts on human reactions to partial gravity environments, derive design requirements based on these facts, and apply the requirements to a partial gravity situation which, for this study, was a lunar base.

Capps, Stephen; Lorandos, Jason; Akhidime, Eval; Bunch, Michael; Lund, Denise; Moore, Nathan; Murakawa, Kiosuke

1989-01-01

424

Morphology of partial globozoospermia.  

PubMed

Total globozoospermia is a rare sperm morphology disorder that consists of 100% round-headed, acrosomeless spermatozoa. There is also a larger group of patients whose sperm cells are partially acrosomeless. The aim of this investigation was to describe partial globozoospermia compared to total globozoospermia and normozoospermia. Ejaculates from 10 patients with more than 50% acrosomeless spermatozoa (partial globozoospermia), 3 patients with total globozoospermia, and 9 normozoospermic controls were analyzed with light microscopy, transmission electron microscopy, and flow cytometry. Qualitative and quantitative examination of spermatozoa from the 3 groups shows differences in the percentage of round-headed sperm cells and acrosome malformation. Total globozoospermia presents as a homogenous kind of teratozoospermia. Partial globozoospermia is a distinctive sperm malformation with an increased proportion of round-headed sperm cells and acrosome malformations compared to normozoospermia, which exists separately from total globozoospermia. It thereby contains oval sperm cells that may have distinctive malformations of the sperm head matrix, but also morphologically normal sperm cells that may be used in a clinical setting. PMID:20864651

Dam, Anika H; Ramos, Liliana; Dijkman, Henry B; Woestenenk, Rob; Robben, Hannie; van den Hoven, Leonie; Kremer, Jan A

2011-01-01

425

Partial Differential Equations  

Microsoft Academic Search

We classify singularities of multiple-valued solutions of higher order sys- tems of partial differential equations in the case when projections of the correspond- ing integral manifolds of the Cartan distribution in the jet space to the space of independent variables have Whitney singularities.

Alexander B. GIVENTAL

1907-01-01

426

Planning Partially for Situated Agents  

Microsoft Academic Search

In recent years, within the planning literature there has been a de- parture from approaches computing total plans for given goals, in favour of ap- proaches computing partial plans. Total plans can be seen as (partially ordered) sets of actions which, if executed successfully, would lead to the achievement of the goals. Partial plans, instead, can be seen as (partially

Paolo Mancarella; Fariba Sadri; Giacomo Terreni; Francesca Toni

2004-01-01

427

Root Canal Morphology of Permanent Three-rooted Mandibular First Molars: Part II—Measurement of Root Canal Curvatures  

Microsoft Academic Search

IntroductionThe distolingual (DL) roots of three-rooted mandibular molars often challenge clinicians during root canal therapy. This study investigated canal curvatures in permanent three-rooted mandibular first molars by using micro–computed tomography (micro-CT) scans.

Yongchun Gu; Qun Lu; Ping Wang; Longxing Ni

2010-01-01

428

Changes in the pattern of horseradish peroxidase diffusion into predentin and dentin after cavity preparation in rat molars  

Microsoft Academic Search

Objective: The purpose of this study was to examine the process of reducing dentin permeability in adult rat molars after cavity preparation with horseradish peroxidase as a tracer. Study Design: Class V cavities were prepared on the upper first molars of 18 rats. Horseradish peroxidase was injected into the vascular system at intervals of 3 hours and 3, 5, 7,

Toshio Izumi; Hiroshi Inoue; Hiroshi Matsuura; Fumihiko Mukae; Hiromichi Osoegawa; Hirofumi Hirano; Naoharu Tamura

2001-01-01

429

Diagnostic predictability of digital versus conventional panoramic radiographs in the presurgical evaluation of impacted mandibular third molars  

Microsoft Academic Search

Panoramic radiographs are the most widely used radiological diagnostic technique in dental practice, offering full vision of the maxillas and adjacent regions, but there are shortcomings regarding detailed dentoalveolar exploration. This study compared the precision of digital versus conventional panoramic radiographs in the presurgical evaluation of impacted lower third molars. 390 mandibular third molars were studied in 287 patients; their

E. Ferrús-Torres; J. Gargallo-Albiol; L. Berini-Aytés; C. Gay-Escoda

2009-01-01

430

A comparison of conventional panoramic radiographs with volumetric computed tomography images in the preoperative assessment of impacted mandibular third molars  

Microsoft Academic Search

Purpose: In the present study, we evaluated the geometric, topographic, and anatomic reliability of volumetric computed tomography (VCT) images by comparing conventional panoramic radiographs with reconstructed VCT panoramic and paraxial images before performing third molar surgery. Patients and Methods: A total of 6 anatomic sites on 10 patients who showed a topographic relationship between the apices of the third molar

J. Pawelzik; M. Cohnen; R. Willers; J. Becker

2002-01-01

431

A case report of maxillary second molar with two palatal root canals and a furcal enamel pearl.  

PubMed

This case report presents an uncommon case of maxillary molar with two palatal root canals and an enamel pearl in the furcation area. The article discusses root canal complexities of maxillary second molars as well as possibility of coexisting anomalies in the region that makes radiographic interpretation difficult and compromises the success of endodontic treatment. PMID:23411467

Shojaeian, Shiva; Ghoddusi, Jamileh; Hajian, Sara

2013-01-01

432

Cone-Beam Computed Tomography Evaluation of Maxillary First and Second Molars in Iranian Population: A Morphological Study  

PubMed Central

Introduction: The aim of this in vitro study was to identify the root and canal morphology of maxillary first and second molars in Iranian population by taking and analyzing cone-beam computed tomography (CBCT) scans. Methods and Materials: Extracted maxillary first (n=125) and second (n=125) molars were collected from native Iranians and scanned by using a CBCT scanner. The number of roots and configuration of root canal system were classified according to Vertucci’s classification. Results: Two (1.6%) maxillary first and two (1.6%) maxillary second molars had four roots. Prevalence of root fusion was 2.4% and 8.8% in maxillary first and second molars, respectively. The most common canal morphology in the mesiobuccal roots of three-rooted first and second molars was type I (46.4% and 80.8%, respectively), followed by type VI (17.6%) in first molars. The predominant morphology of distobuccal and palatal roots in first and second molars was type I. Additional canal types were also identified. Conclusion: Profound knowledge of anatomic variations is necessary prior to cleaning and obturation of the root canal system. The most common discovered root morphology was three separate roots in both tooth types. The greatest variation in canal anatomy was discovered in the MB canals of both the first and second molars. PMID:25031592

Rouhani, Armita; Bagherpour, Ali; Akbari, Majid; Azizi, Majid; Nejat, Amirhosein; Naghavi, Neda

2014-01-01

433

Effect of various glucagon\\/insulin molar ratios on blood ketone body levels in rats by use of osmotic minipumps  

Microsoft Academic Search

The bihormonal control by insulin and glucagon of blood ketone body level was studied. Mixed solutions with various molar ratios of glucagon and insulin (GI) were subcutaneously infused continuously for five days by use of the osmotic minipump in the normal rats. The concentrations of insulin and glucagon solution were set at the high GI molar ratio, the moderate GI

Eiichi Ubukata; Osamu Mokuda; Yoshikazu Sakamoto; Naokata Shimizu

1996-01-01

434

GENERAL: Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C8H11NO)  

NASA Astrophysics Data System (ADS)

This paper reports that low-temperature heat capacities of 4-(2-aminoethyl)-phenol (C8H11NO) are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at the interval of 5 K. The energy equivalent, ?calor, of the oxygen-bomb combustion calorimeter has been determined from 0.68 g of NIST 39i benzoic acid to be ?calor = (14674.69±17.49)J.K-1. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ?cU = -(32374.25±12.93)J.g-1. The standard molar enthalpy of combustion for the compound was calculated to be ?cHmominus = -(4445.47 ± 1.77) k. J · mol-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ?fHmominus(C8H11NO, s) = -(274.68 ± 2.06) kJ · mol-1, in accordance with Hess law.

Di, You-Ying; Kong, Yu-Xia; Yang, Wei-Wei; Tan, Zhi-Cheng

2008-09-01

435

Partially coherent ultrafast spectrography  

NASA Astrophysics Data System (ADS)

Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter.

Bourassin-Bouchet, C.; Couprie, M.-E.

2015-03-01

436

Partially coherent ultrafast spectrography.  

PubMed

Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080

Bourassin-Bouchet, C; Couprie, M-E

2015-01-01

437

Laparoscopic partial splenic resection.  

PubMed

Twenty domestic pigs with an average weight of 30 kg were subjected to laparoscopic partial splenic resection with the aim of determining the feasibility, reliability, and safety of this procedure. Unlike the human spleen, the pig spleen is perpendicular to the body's long axis, and it is long and slender. The parenchyma was severed through the middle third, where the organ is thickest. An 18-mm trocar with a 60-mm Endopath linear cutter was used for the resection. The tissue was removed with a 33-mm trocar. The operation was successfully concluded in all animals. No capsule tears occurred as a result of applying the stapler. Optimal hemostasis was achieved on the resected edges in all animals. Although these findings cannot be extended to human surgery without reservations, we suggest that diagnostic partial resection and minor cyst resections are ideal initial indications for this minimally invasive approach. PMID:7773460

Uranüs, S; Pfeifer, J; Schauer, C; Kronberger, L; Rabl, H; Ranftl, G; Hauser, H; Bahadori, K

1995-04-01

438

Partially coherent ultrafast spectrography  

PubMed Central

Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080

Bourassin-Bouchet, C.; Couprie, M.-E.

2015-01-01

439

Partial trisomy 21  

Microsoft Academic Search

Cytogenetic analysis of a 6-year-old girl with moderate mental retardation revealed 46 chromosomes with a tandem translocation (21;21) resulting in a partial trisomy 21. Only the terminal band 21q22 was not in triplicate. G-, Q-, R-, and C-banding techniques and silver nitrate staining of the nucleolus organizer regions (NORs) were used to identify this chromosome fully.

A. Hagemeijer; E. M. E. Smit

1977-01-01

440

Linear Partial Differential Equations  

NSDL National Science Digital Library

This course, presented by MIT and taught by professor Matthew Hancock, covers the partial differential equations of applied mathematics, including diffusion, Laplace/Poisson, and wave equations. Methods and tools for solving these equations are also taught. The course includes lecture notes as well as assignments and exams with solutions. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Hancock, Matthew

441

Partially Reflected Diffusion  

E-print Network

The radiation (reaction, Robin) boundary condition for the continuum diffusion equation is widely used in chemical and biological applications to express reactive boundaries. The underlying trajectories of the diffusing particles are believed to be partially absorbed and partially reflected at the reactive boundary, however, the relation between the reaction (radiation) constant in the Robin boundary condition and the reflection probability is still unclear. In this paper we clarify the issue by finding the relation between the reaction (radiation) constant and the absorption probability of the diffusing trajectories at the boundary. We analyze the Euler scheme for the underlying It\\^o dynamics, which is assumed to have variable drift and diffusion tensor, with partial reflection at the boundary. Trajectories that cross the boundary are terminated with a given probability and otherwise are reflected in a normal or oblique direction. We use boundary layer analysis of the corresponding Wiener path integral to resolve the non-uniform convergence of the probability density function of the numerical scheme to the solution of the Fokker-Planck equation with the Robin boundary condition, as the time step is decreased. We show that the Robin boundary condition is recovered in the limit iff trajectories are reflected in the co-normal direction. We find the relation of the reactive constant to the termination probability. We show the effect of using the new relation in numerical simulations.

A. Singer; Z. Schuss; D. Holcman

2007-09-02

442

Volume graphics  

Microsoft Academic Search

Volume graphics, which employs a volume buffer of voxels for 3D scene representation, is discussed. Volume graphics offers advantages over surface graphics: it is viewpoint independent, insensitive to scene and object complexity, and suitable for the representation of sampled and simulated data sets. Moreover, geometric objects can be mixed with these data sets. Volume graphics supports the visualization of internal

Arie E. Kaufman; Daniel Cohen-Or; Roni Yagel

1993-01-01

443

Selenium/mercury molar ratios in freshwater, marine, and commercial fish from the USA: variation, risk, and health management.  

PubMed

Fish provide healthy protein as well as recreational and cultural benefits, but can also contain mercury (Hg), polychlorinated biphenyls (PCBs), and other contaminants that have adverse effects on humans and other organisms, particularly developing fetuses. Recently, some authors have suggested that a molar excess of selenium (Se) [e.g., selenium/mercury (Se/Hg) molar ratio >1] confers protection from Hg toxicity derived from fish consumption. Herein, we review our studies of Hg and Se in freshwater, marine, and commercial fish (mainly marine), examining the following: (1) whether and how Se/Hg molar ratios vary among species; (2) whether and how the molar ratios vary within species; (3) whether the molar ratios differ between freshwater and saltwater fish; (4) whether mean molar ratio values provide a reliable indication of potential risk to fish consumers; and (5) whether mean Se/Hg molar ratios are sufficiently constant (e.g., low variation) to allow for use in risk assessment, risk management, or risk communication. In saltwater fish, mean Se/Hg molar ratios varied from 0.3 in mako shark to 68.1 in whiting. For freshwater fish, the mean ratios varied from 0.68 in bowfin to 20.8 in black crappie. Commercial seafood (mainly saltwater) showed great variation in ratios; shrimp and scallops had very high ratios. There was somewhat less variability in the ratios for freshwater fish compared with the fish from saltwater, but there was no overall predictable difference in variation in Se/Hg molar ratios. For both saltwater and freshwater fish, some species with mean molar ratios above 1 had a significant proportion of individual fish with molar ratios below 1. Overall, this indicates great variation in measures of central tendencies and in measures of dispersion. We suggest that relying on the Se/Hg molar ratio as a method of predicting reduced risk from Hg toxicity is problematic because of the great variation among and within fish species, and the variation is not