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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reynolds, Jacob G.

2013-07-01

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 changemore » 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)« less

Isentropic expansion and related thermodynamic properties of non-ionic amphiphile-water mixtures.

PubMed

Reis, João Carlos R; Douhéret, Gérard; Davis, Michael I; Fjellanger, Inger Johanne; Høiland, Harald

2008-01-28

A concise thermodynamic formalism is developed for the molar isentropic thermal expansion, ES,m = ( partial differential Vm/ partial differential T)(Sm,x), and the ideal and excess quantities for the molar, apparent molar and partial molar isentropic expansions of binary liquid mixtures. Ultrasound speeds were determined by means of the pulse-echo-overlap method in aqueous mixtures of 2-methylpropan-2-ol at 298.15 K over the entire composition range. These data complement selected extensive literature data on density, isobaric heat capacity and ultrasound speed for 9 amphiphile (methanol, ethanol, propan-1-ol, propan-2-ol, 2-methylpropan-2-ol, ethane-1,2-diol, 2-methoxyethanol, 2-ethoxyethanol or 2-butoxyethanol)-water binary systems, which form the basis of tables listing molar and excess molar isobaric expansions and heat capacities, and molar and excess molar isentropic compressions and expansions at 298.15 K and at 65 fixed mole fractions spanning the entire composition range and fine-grained in the water-rich region. The dependence on composition of these 9 systems is graphically depicted for the excess molar isobaric and isentropic expansions and for the excess partial molar isobaric and isentropic expansions of the amphiphile. The analysis shows that isentropic thermal expansion properties give a much stronger response to amphiphile-water molecular interactions than do their isobaric counterparts. Depending on the pair property-system, the maximum excess molar isentropic value is generally twenty- to a hundred-fold greater than the corresponding maximum isobaric value, and occurs at a lower mole fraction of the amphiphile. Values at infinite dilution of the 9 amphiphiles in water are given for the excess partial molar isobaric heat capacity, isentropic compression, isobaric expansion and isentropic expansion. These values are interpreted in terms of the changes occurring when amphiphile molecules cluster into an oligomeric form. Present results are discussed from theoretical and experimental thermodynamic viewpoints. It is concluded that isentropic thermal expansion properties constitute a new distinct resource for revealing particular features and trends in complex mixing processes, and that analyses using these new properties compare favourably with conventional approaches.

Experimental investigation of thermodynamic properties of binary mixture of acetic acid + n-butanol and acetic acid + water at temperature from 293.15 K to 343.15 K

NASA Astrophysics Data System (ADS)

Paul, M. Danish John; Shruthi, N.; Anantharaj, R.

2018-04-01

The derived thermodynamic properties like excess molar volume, partial molar volume, excess partial molar volume and apparent volume of binary mixture of acetic acid + n-butanolandacetic acid + water has been investigated using measured density of mixtures at temperatures from 293.15 K to 343.15.

Densities, Ultrasonic Speeds, and Excess Properties of Binary Mixtures of Diethylene Glycol with 1-Butanol, 2-Butanol, and 1,4-Butanediol at Different Temperatures

NASA Astrophysics Data System (ADS)

Ali, Anwar; Ansari, Sana; Uzair, Sahar; Tasneem, Shadma; Nabi, Firdosa

2015-11-01

Densities ρ and ultrasonic speeds u for pure diethylene glycol, 1-butanol, 2-butanol, and 1,4-butanediol and for their binary mixtures over the entire composition range were measured at 298.15 K, 303.15 K, 308.15 K, and 313.15 K. Using these data, the excess molar volumes, VE_m, deviations in isentropic compressibilities, {\\varDelta }ks, apparent molar volumes, V_{φi} , partial molar volumes, overline{V}_{m,i} , and excess partial molar volumes, overline{V}_{m,i}^E , have been calculated over the entire composition range, and also the excess partial molar volumes of the components at infinite dilution, overline{V}_{m,i}^{E,infty } have been calculated. The excess functions have been correlated using the Redlich-Kister equation at different temperatures. The variations of these derived parameters with composition and temperature are presented graphically.

Partial molar volumes and viscosities of aqueous hippuric acid solutions containing LiCl and MnCl2 · 4H2O at 303.15 K

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Tawde, P. D.; Zinjade, A. B.; Shaikh, A. I.

2015-09-01

Density (ρ) and viscosity (η) of aqueous hippuric acid (HA) solutions containing LiCl and MnCl2 · 4H2O have been studied at 303.15 K in order to understand volumetric and viscometric behavior of these systems. Apparent molar volume (φv) of salts were calculated from density data and fitted to Massons relation and partial molar volumes (φ{v/0}) at infinite dilution were determined. Relative viscosity data has been used to determine viscosity A and B coefficients using Jones-Dole relation. Partial molar volume and viscosity coefficients have been discussed in terms of ion-solvent interactions and overall structural fittings in solution.

Hydration of alcohol clusters in 1-propanol-water mixture studied by quasielastic neutron scattering and an interpretation of anomalous excess partial molar volume.

PubMed

Misawa, M; Inamura, Y; Hosaka, D; Yamamuro, O

2006-08-21

Quasielastic neutron scattering measurements have been made for 1-propanol-water mixtures in a range of alcohol concentration from 0.0 to 0.167 in mole fraction at 25 degrees C. Fraction alpha of water molecules hydrated to fractal surface of alcohol clusters in 1-propanol-water mixture was obtained as a function of alcohol concentration. Average hydration number N(ws) of 1-propanol molecule is derived from the value of alpha as a function of alcohol concentration. By extrapolating N(ws) to infinite dilution, we obtain values of 12-13 as hydration number of isolated 1-propanol molecule. A simple interpretation of structural origin of anomalous excess partial molar volume of water is proposed and as a result a simple equation for the excess partial molar volume is deduced in terms of alpha. Calculated values of the excess partial molar volumes of water and 1-propanol and the excess molar volume of the mixture are in good agreement with experimental values.

Properties of L-ascorbic acid in water and binary aqueous mixtures of D-glucose and D-fructose at different temperatures

NASA Astrophysics Data System (ADS)

Sharma, Ravi; Thakur, R. C.; Sani, Balwinder; Kumar, Harsh

2017-12-01

Using density and sound velocity partial molar volumes, partial molar adiabatic compressibilities, partial molar expansibilities and structure of L-ascorbic acid have been determined in water and aqueous mixtures of D-glucose and D-fructose at different concentrations and temperatures. Masson's equation was used to analyze the measured data. The obtained parameters have been interpreted in terms of solute-solute and solute-solvent interactions. It is found that the L-ascorbic acid acts as structure breaker in water as well in binary studied mixtures.

[Orthodontic partial disimpaction of mandibular third molars prior to surgical extraction].

PubMed

Derton, Nicolà; Perini, Alessandro; Giordanetto, José; Biondi, Giovanni; Siciliani, Giuseppe

2009-06-01

Odontodysplasia of the third molars is a relatively common anomaly. The frequent complications associated with this disorder very often constitute an indication for extraction of the third molar. This surgical treatment can damage the lower alveolar nerve and/or trigger distal bone loss of the second molar, thus jeopardizing the future status of the periodontium. The author presents two case studies treated exclusively with miniscrews with no dental anchorage in order to achieve partial eruption of the third molar moving it away from the lower alveolar nerve and to avoid unwanted impact on other teeth. Following this procedure, the third molar was extracted without complications. In conclusion, this approach can offer an alternative to surgical treatment alone in cases where the proximity of tooth and nerve poses a significant risk.

A simple way to intrude overerupted upper second molars with miniscrews.

PubMed

Cao, Yang; Liu, Chufeng; Wang, Chunxian; Yang, Xiaoyu; Duan, Peijia; Xu, Chenrong

2013-12-01

Various methods of using skeletal anchorage for the intrusion of overerupted maxillary molars have been reported; however, it is difficult to intrude the overerupted upper second molars because of the low bone density in the region of the tuberosity. This article illustrates a new treatment method using partial fixed edgewise appliances and miniscrews to intrude the overerupted upper second molars. The miniscrews were applied to reinforce the anchorage of the upper first molar. The intrusive force was generated by the Ni-Ti wire. The clinical results showed a significant intrusion effect without root resorption or periodontal problems. This report demonstrates that the combination of partial conventional fixed appliances with miniscrews is a simple and effective treatment option to intrude overerupted upper second molars, especially in situations where miniscrews cannot be inserted directly next to the second molar. © 2013 by the American College of Prosthodontists.

Live-born diploid fetus complicated with partial molar pregnancy presenting with pre-eclampsia, maternal anemia, and seemingly huge placenta: A rare case of confined placental mosaicism and literature review.

PubMed

Kawasaki, Kaoru; Kondoh, Eiji; Minamiguchi, Sachiko; Matsuda, Fumihiko; Higasa, Koichiro; Fujita, Kohei; Mogami, Haruta; Chigusa, Yoshitsugu; Konishi, Ikuo

2016-08-01

A partial molar pregnancy almost always ends in miscarriage due to a triploid fetus. We describe a rare case of a singleton, partial molar pregnancy with a seemingly huge placenta, which continued to delivery of a live-born diploid baby. A 27-year-old primigravida suffered from severe pre-eclampsia and progressive anemia. The uterus was enormously enlarged for the gestational age. A cesarean section was performed because of deterioration of maternal status at 25 weeks' gestation, when more than 3000 mL blood spouted concurrently with the delivery of the placenta. The histological examination showed congestion in the decidua, which indicated disturbance of maternal venous return from the intervillous space. The chromosome complement of the placenta and the neonate were 69,XXX and 46,XX, respectively. We also reviewed all published cases of a singleton, partial molar pregnancy. A literature search yielded 18 cases of a singleton, diploid fetus with partial molar pregnancy. The mean gestational age at delivery was 24.5 ± 6.2 weeks, and fetuses survived outside the uterus in only four cases (22.2%). Intriguingly, previous reports numbered 10 cases with diploid placenta as well as five cases with no karyotyping of the placenta, indicating that they may have included a complete mole in a twin pregnancy or placental mesenchymal dysplasia. In conclusion, this was the first case of placentomegaly that presented manifestations of excessive abdominal distension and maternal severe anemia, and the second case of a singleton, partial molar pregnancy confirmed by chromosome analysis resulting in a diploid living baby. © 2016 Japan Society of Obstetrics and Gynecology.

Partial Molar Volumes of Aqua Ions from First Principles.

PubMed

Wiktor, Julia; Bruneval, Fabien; Pasquarello, Alfredo

2017-08-08

Partial molar volumes of ions in water solution are calculated through pressures obtained from ab initio molecular dynamics simulations. The correct definition of pressure in charged systems subject to periodic boundary conditions requires access to the variation of the electrostatic potential upon a change of volume. We develop a scheme for calculating such a variation in liquid systems by setting up an interface between regions of different density. This also allows us to determine the absolute deformation potentials for the band edges of liquid water. With the properly defined pressures, we obtain partial molar volumes of a series of aqua ions in very good agreement with experimental values.

What is the fundamental ion-specific series for anions and cations? Ion specificity in standard partial molar volumes of electrolytes and electrostriction in water and non-aqueous solvents† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc02691a Click here for additional data file.

PubMed Central

Mazzini, Virginia

2017-01-01

The importance of electrolyte solutions cannot be overstated. Beyond the ionic strength of electrolyte solutions the specific nature of the ions present is vital in controlling a host of properties. Therefore ion specificity is fundamentally important in physical chemistry, engineering and biology. The observation that the strengths of the effect of ions often follows well established series suggests that a single predictive and quantitative description of specific-ion effects covering a wide range of systems is possible. Such a theory would revolutionise applications of physical chemistry from polymer precipitation to drug design. Current approaches to understanding specific-ion effects involve consideration of the ions themselves, the solvent and relevant interfaces and the interactions between them. Here we investigate the specific-ion effects trends of standard partial molar volumes and electrostrictive volumes of electrolytes in water and eleven non-aqueous solvents. We choose these measures as they relate to bulk properties at infinite dilution, therefore they are the simplest electrolyte systems. This is done to test the hypothesis that the ions alone exhibit a specific-ion effect series that is independent of the solvent and unrelated to surface properties. The specific-ion effects trends of standard partial molar volumes and normalised electrostrictive volumes examined in this work show a fundamental ion-specific series that is reproduced across the solvents, which is the Hofmeister series for anions and the reverse lyotropic series for cations, supporting the hypothesis. This outcome is important in demonstrating that ion specificity is observed at infinite dilution and demonstrates that the complexity observed in the manifestation of specific-ion effects in a very wide range of systems is due to perturbations of solvent, surfaces and concentration on the underlying fundamental series. This knowledge will guide a general understanding of specific-ion effects and assist in the development of a quantitative predictive theory of ion specificity. PMID:29147533

Determination of thermodynamic properties of poly (cyclohexyl methacrylate) by inverse gas chromatography.

PubMed

Kaya, Ismet; Pala, Cigdem Yigit

2014-07-01

In this work, some thermodynamic properties of poly (cyclohexyl methacrylate) were studied by inverse gas chromatography (IGC). For this purpose, the polymeric substance was coated on Chromosorb W and which was filled into a glass column. The retention times (t(r)) of the probes were determined from the interactions of poly (cyclohexyl methacrylate) with n-pentane, n-hexane, n-heptane, n-octane, n-decane, methanol, ethanol, 2-propanol, butanol, acetone, ethyl methyl ketone, benzene, toluene and o-xylene by IGC technique. Then, the specific volume (Vg(0)) was determined for each probe molecule. By using (1/T; lnVg(0)) graphics, the glass transition temperature of poly (cyclohexyl methacrylate) was found to be 373 K. The adsorption heat under the glass transition temperature (deltaH(a)), and partial molar heat of sorption above the glass transition (deltaH1(S)), partial molar free energy of sorption (deltaG1(S)) and partial molar entropy of sorption (deltaS1(S)) belonging to sorption for every probe were calculated. The partial molar heat of mixing at infinite dilution (deltaH1(infinity)), partial molar free energy of mixing at infinite dilution (deltaG1(infinity)), Flory-Huggins interaction parameter (chi12(infinity)) and weight fraction activity coefficient (a1/w1)(infinity) values of polymer-solute systems were calculated at different column temperatures. The solubility parameters (delta2) of the polymer were obtained by IGC technique.

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

PubMed Central

Jung, Yun-Hoa

2013-01-01

Purpose The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. Materials and Methods The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent second molars. Results A greater percentage of men than women retained at least one third molar. The incidence of third molars decreased with increasing age. The incidence of partially impacted third molars greatly declined after the age of 30. Vertically impacted maxillary third molars and horizontally impacted mandibular third molars were most frequent in all age groups. Among the maxillary third molars, those impacted below the cervical line of the second molar were most frequent in all age groups, and among the mandibular third molars, deeply impacted third molars were most frequent in those aged over 40. Dental caries was the most common radiographic lesion of the third molars. Mesioangularly impacted third molars showed radiographic lesions in 13 (9.5%) adjacent maxillary second molars and 117 (27.4%) mandibular second molars. Conclusion The number of remaining third molars decreased and the percentage of Class C depth increased with age. Caries was the most frequent lesion in third molars. Partially impacted mesioangular third molars showed a high incidence of caries or periodontal bone loss of the adjacent second molar. Regular oral examination will be essential to keep asymptomatic third molars in good health. PMID:24380060

Solute-solvent interactions in solutions of 2-hydroxy-5-chloro-3-nitroacetophenone isonicotinoylhydrazone in N, N-dimethylformamide at 298-313 K according to ultrasonic and viscometric data

NASA Astrophysics Data System (ADS)

Dikkar, A. B.; Pethe, G. B.; Aswar, A. S.

2015-12-01

Density (ρ), speed of sound ( u), and viscosity (η), measurements have been carried on 2-hydroxy- 5-chloro-3-nitroacetophenone isonicotinoylhydrazone (HCNAIH) in N, N-dimethylformamide at 298.15, 303.15, 308.15, and 313.15 K. Adiabatic compressibility (βs), intermolecular free length ( L f), acoustic impedance ( Z), internal pressure ( P int), the apparent molar volume ( V w), limiting apparent molar volume ( V w 0), partial molar expansibility (wE 0), apparent molar adiabatic compressibility ( K w), limiting apparent molar adiabatic compressibility ( K w 0), viscosity B coefficients of Jones-Dole equation have been calculated. The activation free energy (Δμ 2 0 *) for viscous flow in solution have been calculated from B coefficient and partial molar volume data. The calculated parameters are used to interpret the solute-solvent interactions and structure forming/breaking ability of solute in DMF.

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

PubMed

Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

2014-10-03

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

A finite element analysis of the stress distribution to the mandible from impact forces with various orientations of third molars*

PubMed Central

Liu, Yun-feng; Wang, Russell; Baur, Dale A.; Jiang, Xian-feng

2018-01-01

Objective: To investigate the stress distribution to the mandible, with and without impacted third molars (IM3s) at various orientations, resulting from a 2000-Newton impact force either from the anterior midline or from the body of the mandible. Materials and methods: A 3D mandibular virtual model from a healthy dentate patient was created and the mechanical properties of the mandible were categorized to 9 levels based on the Hounsfield unit measured from computed tomography (CT) images. Von Mises stress distributions to the mandibular angle and condylar areas from static impact forces (Load I-front blow and Load II left blow) were evaluated using finite element analysis (FEA). Six groups with IM3 were included: full horizontal bony, full vertical bony, full 450 mesioangular bony, partial horizontal bony, partial vertical, and partial 450 mesioangular bony impaction, and a baseline group with no third molars. Results: Von Mises stresses in the condyle and angle areas were higher for partially than for fully impacted third molars under both loading conditions, with partial horizontal IM3 showing the highest fracture risk. Stresses were higher on the contralateral than on the ipsilateral side. Under Load II, the angle area had the highest stress for various orientations of IM3s. The condylar region had the highest stress when IM3s were absent. Conclusions: High-impact forces are more likely to cause condylar rather than angular fracture when IM3s are missing. The risk of mandibular fracture is higher for partially than fully impacted third molars, with the angulation of impaction having little effect on facture risk. PMID:29308606

Studies of Partial Molar Volumes of Some Narcotic-Analgesic Drugs in Aqueous-Alcoholic Mixtures at 25°C

NASA Astrophysics Data System (ADS)

Sharma, Poonam; Chauhan, S.; Syal, V. K.; Chauhan, M. S.

2008-04-01

Partial molar volumes of the drugs Parvon Spas, Parvon Forte, Tramacip, and Parvodex in aqueous mixtures of methanol (MeOH), ethanol (EtOH), and propan-1-ol (1-PrOH) have been determined. The data have been evaluated using the Masson equation. The parameters, apparent molar volumes {(φ_v)}, partial molar volumes {(φ_v0)}, and S v values (experimental slopes) have been interpreted in terms of solute solvent interactions. In addition, these studies have also been extended to determine the effect of these drugs on the solvation behavior of an electrolyte (sodium chloride), a surfactant (sodium dodecyl sulfate), and a non-electrolyte (sucrose). It can be inferred from these studies that all drug cations can be regarded as structure makers/promoters due to hydrophobic hydration. Furthermore, the results are correlated to understand the solution behavior of drugs in aqueous-alcoholic systems, as a function of the nature of the alcohol and solutes.

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

PubMed

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

2010-12-15

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, σ = 0.99 kcal mol (- 1) for a test set of 120 organic molecules).

Determination of partial molar volumes from free energy perturbation theory†

PubMed Central

Vilseck, Jonah Z.; Tirado-Rives, Julian

2016-01-01

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 cm3 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

Determination of partial molar volumes from free energy perturbation theory.

PubMed

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

2015-04-07

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.

The retention of pit and fissure sealants placed in primary school children by Dental Health Services, Victoria.

PubMed

Messer, L B; Calache, H; Morgan, M V

1997-08-01

The benefit of a public sector sealant programme for children in Australia is yet to be established. This study evaluated sealants placed by therapists of the School Dental Service in Victoria, between 1989 and 1994, on permanent teeth of children in 15 primary schools in Melbourne. Seven hundred and seventy four children aged 6-12 years were examined in school dental clinics by six calibrated examiners. A total of 5363 sealants placed on 2875 permanent teeth (including 2616 first molars, 91 per cent of sample) up to four and a half years previously was examined. Values for complete and partial sealant retention were highest for premolars (86 per cent, 9 per cent respectively, total 95 per cent); similar for occlusal surfaces of maxillary and mandibular first molars (63 per cent, 30 per cent; 62 per cent, 32 per cent respectively) and buccal pits of mandibular molars (66 per cent); and low for pits/fissures of Carabelli's cusps of maxillary molars (44 per cent). Cross-sectional examination up to 24 months for both maxillary and mandibular first molars indicated average values of 67 per cent complete retention, 27 per cent partial retention, 6 per cent missing; thereafter complete retention decreased and partial retention increased. Sealant failures in the six months post-placement were attributed to technique failure. Regardless of sealant retention, caries experience was low under partially retained or missing sealants (4.5 per cent) and completely retained sealants (0.4 per cent). It is concluded that the SDS sealant programme is a sound preventive dental public health approach.

Dilatometric measurement of the partial molar volume of water sorbed to durum wheat flour.

PubMed

Hasegawa, Ayako; Ogawa, Takenobu; Adachi, Shuji

2013-01-01

Moisture sorption isotherms were measured at 25 °C for untreated, dry-heated and pre-gelatinized durum wheat flour samples. The isotherms could be expressed by the Guggenheim-Anderson-de Boer equation. The amount of water sorbed to the untreated flour was highest for low water activity, with water sorbed to the pre-gelatinized and dry-heated flour samples following. The dry-heated and pregelatinized flour samples exhibited the same dependence of the moisture content on the partial molar volume of water at 25 °C as the untreated flour. The partial molar volume of water was ca. 9 cm(3)/mol at a moisture content of 0.03 kg-H2O/kg-d.m. The volume increased with increasing moisture content, and reached a constant value of ca. 17.5 cm(3)/mol at a moisture content of 0.2 kg-H2O/kg-d.m. or higher.

Protraction of mandibular second and third molars assisted by partial corticision and miniscrew anchorage.

PubMed

Mimura, Hiroshi

2013-08-01

A woman, aged 47 years 6 months, with an anterior open bite and a left-shifted mandible was treated with a mandibular right first molar extraction and without orthognathic surgery. However, her mandibular second molar did not move mesially during treatment because of the dense lamina dura; therefore, corticision was applied only on the mesial aspect of the mandibular second molar, and a miniscrew was inserted simultaneously. Corticision was introduced as a supplemental dentoalveolar surgery in orthodontic therapy to achieve accelerated tooth movement with minimal surgical intervention. In this technique, a reinforced scalpel was used as a thin chisel to separate the interproximal cortices transmucosally without a flap. This technique was applied not to accelerate tooth movement, but to protract the mandibular molars. One miniscrew was inserted on the mesiobuccal side of the mandibular right molar for protraction and intrusion. In addition, 2 miniscrews were inserted in the buccal sides of the maxillary first and second molars and the palatal side of the maxillary first molar to intrude them for correction of the mandibular shift and the cant of the occlusal plane. Excellent occlusion and correction of the anterior open bite were achieved without surgery. At the 2-year follow-up examination, the patient had a good occlusion and showed good stability with no opening of the extraction space. A partial corticision is an effective option for facilitating movement of mandibular molars. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

NASA Astrophysics Data System (ADS)

Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

2016-04-01

Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

Thermodynamic properties of deep eutectic solvent and ionic liquid mixtures at temperatures from 293.15 K to 343.15 K

NASA Astrophysics Data System (ADS)

Achsah, R. S.; Shyam, S.; Mayuri, N.; Anantharaj, R.

2018-04-01

Deep eutectic solvents (DES) and ionic liquids (ILs) have their applications in various fields of research and in industries due to their attractive physiochemical properties. In this study, the combined thermodynamic properties of DES (choline chloride-glycerol) + IL1 (1-butyl-3-methylimiazolium acetate) and DES(choline chloride-glycerol) + IL2 (1-ethyl-3-methylimadzolium ethyl sulphate) have been studied. The thermodynamic properties such as excess molar volume, partial molar volume, excess partial molar volume and apparent molar volume were calculated for different mole fractions ranging from 0 to 1 and varying temperatures from 293.15 K to 343.15 K. In order to know the solvent properties of DESs and ILs mixtures at different temperatures and their molecular interactions to enhance the solvent performance and process efficiency at fixed composition and temperature the thermodynamic properties were analyzed.

Study on the interaction of the toxic food additive carmoisine with serum albumins: a microcalorimetric investigation.

PubMed

Basu, Anirban; Kumar, Gopinatha Suresh

2014-05-30

The interaction of the synthetic azo dye and food colorant carmoisine with human and bovine serum albumins was studied by microcalorimetric techniques. A complete thermodynamic profile of the interaction was obtained from isothermal titration calorimetry studies. The equilibrium constant of the complexation process was of the order of 10(6)M(-1) and the binding stoichiometry was found to be 1:1 with both the serum albumins. The binding was driven by negative standard molar enthalpy and positive standard molar entropy contributions. The binding affinity was lower at higher salt concentrations in both cases but the same was dominated by mostly non-electrostatic forces at all salt concentrations. The polyelectrolytic forces contributed only 5-8% of the total standard molar Gibbs energy change. The standard molar enthalpy change enhanced whereas the standard molar entropic contribution decreased with rise in temperature but they compensated each other to keep the standard molar Gibbs energy change almost invariant. The negative standard molar heat capacity values suggested the involvement of a significant hydrophobic contribution in the complexation process. Besides, enthalpy-entropy compensation phenomenon was also observed in both the systems. The thermal stability of the serum proteins was found to be remarkably enhanced on binding to carmoisine. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermodynamic properties of hyperbranched polymer, Boltorn U3000, using inverse gas chromatography.

PubMed

Domańska, Urszula; Zołek-Tryznowska, Zuzanna

2009-11-19

Mass-fraction activity coefficients at infinite dilution (Omega13(infinity)) of alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C8), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) in the hyperbranched polymer, Boltorn U3000 (B-U3000), have been determined by inverse gas chromatography (IGC) using the polymer as the stationary phase. The measurements were carried out at different temperatures between 308.15 and 348.15 K. The density and thermophysical properties of polymer were described. The specific retention volume (V(g)), the Flory-Huggins interaction parameter (chi13(infinity)), the molar enthalpy of sorption (the partial molar enthalpies of solute dissolution) (Delta(s)H), the partial molar excess enthalpy at infinite dilution of the solute and polymer (DeltaH1(E,infinity)), the partial molar Gibbs excess energy at infinite dilution (DeltaG1(E,infinity)), and the solubility parameter (delta3) were calculated.

The management of an endodontically abscessed tooth: patient health state utility, decision-tree and economic analysis

PubMed Central

Balevi, Ben; Shepperd, Sasha

2007-01-01

Background A frequent encounter in clinical practice is the middle-aged adult patient complaining of a toothache caused by the spread of a carious infection into the tooth's endodontic complex. Decisions about the range of treatment options (conventional crown with a post and core technique (CC), a single tooth implant (STI), a conventional dental bridge (CDB), and a partial removable denture (RPD)) have to balance the prognosis, utility and cost. Little is know about the utility patients attach to the different treatment options for an endontically abscessed mandibular molar and maxillary incisor. We measured patients' dental-health-state utilities and ranking preferences of the treatment options for these dental problems. Methods Forty school teachers ranked their preferences for conventional crown with a post and core technique, a single tooth implant, a conventional dental bridge, and a partial removable denture using a standard gamble and willingness to pay. Data previously reported on treatment prognosis and direct "out-of-pocket" costs were used in a decision-tree and economic analysis Results The Standard Gamble utilities for the restoration of a mandibular 1st molar with either the conventional crown (CC), single-tooth-implant (STI), conventional dental bridge (CDB) or removable-partial-denture (RPD) were 74.47 [± 6.91], 78.60 [± 5.19], 76.22 [± 5.78], 64.80 [± 8.1] respectively (p < 0.05). Their respective Willingness-to-Pay ($CDN) were 1,782.05 [± 361.42], 1,871.79 [± 349.44], 1,605.13 [± 348.10], 1,351.28 [± 368.62] (p < 0.05). The standard gamble utilities for the restoration of a maxillary central incisor with a CC, STI, CDB and RPD were 88.50 [± 6.12], 90.68 [± 3.41], 89.78 [± 3.81] and 91.10 [± 3.57] respectively (p > 0.05). Their respective willingness-to-pay ($CDN) were: 1,782.05 [± 361.42], 1,871.79 [± 349.44], 1,605.13 [± 348.10] and 1,351.28 [± 368.62]. A statistical difference was found between the utility of treating a maxillary central incisor and mandibular 1st-molar (p < 0.05). The expected-utility-value for a 5-year prosthetic survival was highest for the CDB and the STI treatment of an abscessed mandibular molar (74.75 and 71.47 respectively) and maxillary incisor (86.24 and 84.91 respectively). This held up to a sensitivity analysis when the success of root canal therapy and the risk of damage to the adjacent tooth were varied. The RPD for both the molar and incisor was the favored treatment based on a cost-utility (3.85 and 2.74 CND$ per year of tooth saved respectively) and cost-benefit analysis (0.92 to 0.60 CND$ of cost per $ of benefit, respectively) for a prosthetic clinical survival of 5-years. Conclusion The position of the abscessed tooth and the amount of insurance coverage influences the utility and rank assigned by patients to the different treatment options. STI and CDB have optimal EUVs for a 5-year survival outcome, and RPD has significantly lower cost providing the better cost:benefit ratio. PMID:18053267

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

PubMed

Slavchov, Radomir I; Ivanov, Tzanko I

2014-02-21

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 = αQ(∇E - U∇·E/3), where the quadrupolarizability αQ 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 = (αQ/3ɛ)(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.

On a relationship between molecular polarizability and partial molar volume in water.

PubMed

Ratkova, Ekaterina L; Fedorov, Maxim V

2011-12-28

We reveal a universal relationship between molecular polarizability (a single-molecule property) and partial molar volume in water that is an ensemble property characterizing solute-solvent systems. Since both of these quantities are of the key importance to describe solvation behavior of dissolved molecular species in aqueous solutions, the obtained relationship should have a high impact in chemistry, pharmaceutical, and life sciences as well as in environments. We demonstrated that the obtained relationship between the partial molar volume in water and the molecular polarizability has in general a non-homogeneous character. We performed a detailed analysis of this relationship on a set of ~200 organic molecules from various chemical classes and revealed its fine well-organized structure. We found that this structure strongly depends on the chemical nature of the solutes and can be rationalized in terms of specific solute-solvent interactions. Efficiency and universality of the proposed approach was demonstrated on an external test set containing several dozens of polyfunctional and druglike molecules.

Partial molar volume of proteins studied by the three-dimensional reference interaction site model theory.

PubMed

Imai, Takashi; Kovalenko, Andriy; Hirata, Fumio

2005-04-14

The three-dimensional reference interaction site model (3D-RISM) theory is applied to the analysis of hydration effects on the partial molar volume of proteins. For the native structure of some proteins, the partial molar volume is decomposed into geometric and hydration contributions using the 3D-RISM theory combined with the geometric volume calculation. The hydration contributions are correlated with the surface properties of the protein. The thermal volume, which is the volume of voids around the protein induced by the thermal fluctuation of water molecules, is directly proportional to the accessible surface area of the protein. The interaction volume, which is the contribution of electrostatic interactions between the protein and water molecules, is apparently governed by the charged atomic groups on the protein surface. The polar atomic groups do not make any contribution to the interaction volume. The volume differences between low- and high-pressure structures of lysozyme are also analyzed by the present method.

Infinitely dilute partial molar properties of proteins from computer simulation.

PubMed

Ploetz, Elizabeth A; Smith, Paul E

2014-11-13

A detailed understanding of temperature and pressure effects on an infinitely dilute protein's conformational equilibrium requires knowledge of the corresponding infinitely dilute partial molar properties. Established molecular dynamics methodologies generally have not provided a way to calculate these properties without either a loss of thermodynamic rigor, the introduction of nonunique parameters, or a loss of information about which solute conformations specifically contributed to the output values. Here we implement a simple method that is thermodynamically rigorous and possesses none of the above disadvantages, and we report on the method's feasibility and computational demands. We calculate infinitely dilute partial molar properties for two proteins and attempt to distinguish the thermodynamic differences between a native and a denatured conformation of a designed miniprotein. We conclude that simple ensemble average properties can be calculated with very reasonable amounts of computational power. In contrast, properties corresponding to fluctuating quantities are computationally demanding to calculate precisely, although they can be obtained more easily by following the temperature and/or pressure dependence of the corresponding ensemble averages.

Experimental Study on Rise Husk Ash & Fly Ash Based Geo-Polymer Concrete Using M-Sand

NASA Astrophysics Data System (ADS)

Nanda Kishore, G.; Gayathri, B.

2017-08-01

Serious environmental problems by means of increasing the production of Ordinary Portland cement (OPC), which is conventionally used as the primary binder to produce cement concrete. An attempt has been made to reduce the use of ordinary Portland cement in cement concrete. There is no standard mix design of geo-polymer concrete, an effort has been made to know the physical, chemical properties and optimum mix of geo-polymer concrete mix design. Concrete cubes of 100 x 100 x 100 mm were prepared and cured under steam curing for about 24 hours at temperature range of 40°C to 60°C. Fly ash is replaced partially with rice husk ash at percentage of 10%, 15% and 25%. Sodium hydroxide and sodium silicate are of used as alkaline activators with 5 Molar and 10 Molar NaOH solutions. Natural sand is replaced with manufacture sand. Test results were compared with controlled concrete mix of grade M30. The results shows that as the percentage of rice husk ash and water content increases, compressive strength will be decreases and as molarity of the alkaline solution increases, strength will be increases.

Utility of p57 immunohistochemistry in differentiating between complete mole, partial mole & non-molar or hydropic abortus.

PubMed

Samadder, Abhimanyu; Kar, Rakhee

2017-01-01

There is considerable inter-observer variability in the diagnosis of molar pregnancies by histomorphological examination of products of conception (POC). The p57KIP2 gene is paternally imprinted and expressed from the maternal allele. On immunohistochemistry (IHC) with p57, complete mole (CM) shows absent staining whereas hydropic abortus (HA) and partial mole (PM) show positive staining. This study was undertaken to evaluate the role of p57 IHC along with histomorphology in differentiating between CM, PM and non-molar or HA. This was a cross-sectional study over a period of three and a half years on archival material. Detailed histomorphological review along with p57 IHC was carried out in 28 diagnosed cases (23 CM, 4 PM and 1 molar pregnancy not categorized) and 25 controls of four normal placentas and 21 POC (8 non-hydropic and 13 HA). In 14.8 per cent (4/27) cases, there was discordance in accurate subtyping of molar pregnancy. One case of CM showed inconsistent IHC pattern. In 15.4 per cent (2/13) HA, molar pregnancy was final diagnosis. After final review, there were 25 CM, five PM, 22 non-molar controls including 10 HA and one not assigned (PM/HA). IHC with p57 was negative in 96 per cent CM and positive in 100 and 95 per cent PM and non-molar controls, respectively. This study showed that negative p57KIP2 immunostaining reliably identified CM and could be used in association with the histological findings to distinguish CM from its mimics.

The influence of surface state and saturation state on the dissolution kinetics of biogenic aragonite in seawater

USGS Publications Warehouse

Acker, James G.; Byrne, R.H.

1989-01-01

Uses several realistic partial molar volume changes (??V) for aragonite dissolution in seawater. Indicates that the molar volume change for aragonite dissolution is within the bounds -37 cm 3/mole ?????V ??? -39.5 cm3/mole. -from Authors

Hippocampus-dependent spatial memory impairment due to molar tooth loss is ameliorated by an enriched environment.

PubMed

Kondo, Hiroko; Kurahashi, Minori; Mori, Daisuke; Iinuma, Mitsuo; Tamura, Yasuo; Mizutani, Kenmei; Shimpo, Kan; Sonoda, Shigeru; Azuma, Kagaku; Kubo, Kin-ya

2016-01-01

Teeth are crucial, not only for mastication, but for overall nutrition and general health, including cognitive function. Aged mice with chronic stress due to tooth loss exhibit impaired hippocampus-dependent learning and memory. Exposure to an enriched environment restores the reduced hippocampal function. Here, we explored the effects of an enriched environment on learning deficits and hippocampal morphologic changes in aged senescence-accelerated mouse strain P8 (SAMP8) mice with tooth loss. Eight-month-old male aged SAMP8 mice with molar intact or with molars removed were housed in either a standard environment or enriched environment for 3 weeks. The Morris water maze was performed for spatial memory test. The newborn cell proliferation, survival, and differentiation in the hippocampus were analyzed using 5-Bromodeoxyuridine (BrdU) immunohistochemical method. The hippocampal brain-derived neurotrophic factor (BDNF) levels were also measured. Mice with upper molars removed (molarless) exhibited a significant decline in the proliferation and survival of newborn cells in the dentate gyrus (DG) as well as in hippocampal BDNF levels. In addition, neuronal differentiation of newly generated cells was suppressed and hippocampus-dependent spatial memory was impaired. Exposure of molarless mice to an enriched environment attenuated the reductions in the hippocampal BDNF levels and neuronal differentiation, and partially improved the proliferation and survival of newborn cells, as well as the spatial memory ability. These findings indicated that an enriched environment could ameliorate the hippocampus-dependent spatial memory impairment induced by molar tooth loss. Copyright © 2015 Elsevier Ltd. All rights reserved.

Distal cervical caries in the mandibular second molar: an indication for the prophylactic removal of third molar teeth? Update.

PubMed

McArdle, Louis W; McDonald, Fraser; Jones, Judith

2014-02-01

In 2005 we reported the clinical findings of 100 patients who had mandibular third molars removed because of distal cervical caries in the mandibular second molar. The aim of this follow-up study was to find out whether the findings in a new group of patients corroborate those of our previous study. We report on the clinical features of 239 patients (mean (SD) age 32.1 (7.85) years, range 20-65) who had 288 mandibular third molars removed because of distal cervical caries in the second molar. Patients had better dental health than average, and 67% had a DMF (decayed, missing, or filled) score of 5 or less. In 89% of third molars the mesial angulation was between 40° and 80°. Distal cervical caries in second molars is a late complication of third molar retention. The prophylactic removal of a partially erupted mesioangular third molar will prevent distal cervical caries forming in the second molar tooth. Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Enthalpy of mixing of liquid Co–Sn alloys

PubMed Central

Yakymovych, A.; Fürtauer, S.; Elmahfoudi, A.; Ipser, H.; Flandorfer, H.

2014-01-01

A literature overview of enthalpy of mixing data for liquid Co–Sn alloys shows large scattering but no clear temperature dependence. Therefore drop calorimetry was performed in the Co–Sn system at twelve different temperatures in 100 K steps in the temperature range (673 to 1773) K. The integral enthalpy of mixing was determined starting from 1173 K and fitted to a standard Redlich–Kister polynomial. In addition, the limiting partial molar enthalpy of Co in Sn was investigated by small additions of Co to liquid Sn at temperatures (673 to 1773) K. The integral and partial molar enthalpies of the Co–Sn system generally show an exothermic mixing behavior. Significant temperature dependence was detected for the enthalpies of mixing. The minimum integral enthalpy values vary with rising temperature from approx. −7820 J/mol at T = 1173 K to −1350 J/mol at T = 1773 K; the position of the minimum is between (59 and 61) at.% Co. The results are discussed and compared with literature data available for this system. X-ray studies and scanning electron microscopy of selected alloys obtained from the calorimetric measurements were carried out in order to check the completeness of the solution process. PMID:24994940

Chemical thermodynamics of ultrasound speed in solutions and liquid mixtures.

PubMed

Reis, João Carlos R; Santos, Angela F S; Lampreia, Isabel M S

2010-02-01

A comprehensive formalism is developed to treat thermodynamically speed of ultrasound data for solutions and liquid mixtures. For solutions, the apparent speed of ultrasound of a solute is introduced and proposed to take the place of empirically defined quantities. The partial speed of ultrasound of a solute is defined and related to the partial molar volume and partial molar isentropic compression. For liquid mixtures, the concept of speed of sound before mixing pure liquids is presented and used to define the change in speed of ultrasound upon ideal mixing, which is predicted to be generally a negative quantity. A new thermodynamic equation is derived linking the values for excess speed of ultrasound, excess molar volume and excess molar isentropic compression of a mixture, and its applications are discussed. Ideal and excess apparent speeds of ultrasound, as well as ideal and excess partial speeds of ultrasound, are defined for substances making up a liquid mixture. Accurate speeds of ultrasound in 31 mixtures of water with the amphiphile 2-(ethylamino)ethanol at 293.15 K are reported. These data are used to demonstrate the ability of the apparent speed of ultrasound to describe the impact of solutes on sonic properties of solutions and the advantages of analysing thermodynamic properties of binary liquid mixtures in terms of the dependence on composition of Balankina's ratios between excess and ideal values. It is concluded that the new thermodynamic functions defined for speeds of ultrasound in solutions and liquid mixtures give, at the least, equivalent information on molecular aspects to the usual functions related to the isentropic compressibility, without needing density data for this purpose.

Partial molar volume of anionic polyelectrolytes in aqueous solution.

PubMed

Salamanca, Constain; Contreras, Martín; Gamboa, Consuelo

2007-05-15

In this work the partial molar volumes (V) of different anionic polyelectrolytes and hydrophobically modified polyelectrolytes (PHM) were measured. Polymers like polymaleic acid-co-styrene, polymaleic acid-co-1-olefin, polymaleic acid-co-vinyl-2-pyrrolidone, and polyacrylic acid (abbreviated as MAS-n, PA-n-K2, AMVP, and PAA, respectively) were employed. These materials were investigated by density measurements in highly dilute aqueous solutions. The molar volume results allow us to discuss the effect of the carboxylic groups and the contributions from the comonomeric principal chain. The PAA presents the smaller V, while the largest V value was for AMVP. The V of PHM shows a linear relationship with the number of methylene groups in the lateral chain. It is found that the magnitude of the contribution per methylene group decreases as the hydrophobic character of the environment increases.

Infinitely Dilute Partial Molar Properties of Proteins from Computer Simulation

PubMed Central

2015-01-01

A detailed understanding of temperature and pressure effects on an infinitely dilute protein’s conformational equilibrium requires knowledge of the corresponding infinitely dilute partial molar properties. Established molecular dynamics methodologies generally have not provided a way to calculate these properties without either a loss of thermodynamic rigor, the introduction of nonunique parameters, or a loss of information about which solute conformations specifically contributed to the output values. Here we implement a simple method that is thermodynamically rigorous and possesses none of the above disadvantages, and we report on the method’s feasibility and computational demands. We calculate infinitely dilute partial molar properties for two proteins and attempt to distinguish the thermodynamic differences between a native and a denatured conformation of a designed miniprotein. We conclude that simple ensemble average properties can be calculated with very reasonable amounts of computational power. In contrast, properties corresponding to fluctuating quantities are computationally demanding to calculate precisely, although they can be obtained more easily by following the temperature and/or pressure dependence of the corresponding ensemble averages. PMID:25325571

The Partial Molar Volume and Compressibility of the FeO Component in Model Basalts (Mixed CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6 Liquids) at 0 GPa: evidence of Fe2+ in 6-fold coordination

NASA Astrophysics Data System (ADS)

Guo, X.; Lange, R. A.; Ai, Y.

2010-12-01

FeO is an important component in magmatic liquids and yet its partial molar volume at one bar is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Moreover, there is growing evidence from spectroscopic studies that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and it is expected that the partial molar volume and compressibility of the FeO component will vary accordingly. We have conducted both density and relaxed sound speed measurements on four liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system: (1) Di-Hd (50:50), (2) An-Hd (50:50), (3) An-Di-Hd (33:33:33) and (4) Hd (100). Densities were measured between 1573 and 1838 K at one bar with the double-bob Archimedean method using molybdenum bobs and crucibles in a reducing gas (1%CO-99%Ar) environment. The sound speeds were measured under similar conditions with a frequency-sweep acoustic interferometer, and used to calculate isothermal compressibility. All the density data for the three multi-component (model basalt) liquids were combined with density data on SiO2-Al2O3-CaO-MgO-K2O-Na2O liquids (Lange, 1997) in a fit to a linear volume equation; the results lead to a partial molar volume (±1σ) for FeO =11.7 ± 0.3(±1σ) cm3/mol at 1723 K. This value is similar to that for crystalline FeO at 298 K (halite structure; 12.06 cm3/mol), which suggests an average Fe2+ coordination of ~6 in these model basalt compositions. In contrast, the fitted partial molar volume of FeO in pure hedenbergite liquid is 14.6 ± 0.3 at 1723 K, which is consistent with an average Fe2+ coordination of 4.3 derived from EXAFS spectroscopy (Rossano, 2000). Similarly, all the compressibility data for the three multi-component liquids were combined with compressibility data on SiO2-Al2O3-CaO-MgO liquids (Ai and Lange, 2008) in a fit to an ideal mixing model for melt compressibility; the results lead to a partial molar compressibility (±1σ) for FeO = 2.4 (± 0.3) 10-2 GPa-1 at 1723 K. In contrast, the compressibility of FeO in pure hedenbergite liquid is more than twice as large: 6.3 (± 0.2) 10-2 GPa-1. When these results are combined with density and sound speed data on CaO-FeO-SiO2 liquids at one bar (Guo et al., 2009), a systematic and linear variation between the partial molar volume and compressibility of the FeO component is obtained, which appears to track changes in the average Fe2+ coordination in these liquids. Therefore, the three most important conclusions of this study are: (1) ideal mixing of volume and compressibility does not occur for all FeO-bearing magmatic liquids, owing to changes in Fe2+ coordination, (2) the partial molar volume and compressibility of FeO varies linearly and systematically with Fe2+ coordination, and (3) ideal mixing of volume and compressibility does occur among the three mixed An-Di-Hd liquids, presumably because of a common, average Fe2+ coordination of ~6.

Theory of chromatography of partially cyclic polymers: Tadpole-type and manacle-type macromolecules.

PubMed

Vakhrushev, Andrey V; Gorbunov, Alexei A

2016-02-12

A theory of chromatography is developed for partially cyclic polymers of tadpole- and manacle-shaped topological structures. We present exact equations for the distribution coefficient K at different adsorption interactions; simpler approximate formulae are also derived, relevant to the conditions of size-exclusion, adsorption, and critical chromatography. Theoretical chromatograms of heterogeneous partially cyclic polymers are simulated, and conditions for good separation by topology are predicted. According to the theory, an effective SEC-radius of tadpoles and manacles is mostly determined by the molar mass M, and by the linear-cyclic composition. In the interactive chromatography, the effect of molecular topology on the retention becomes significant. At the critical interaction point, partial dependences K(Mlin) and K(Mring) are qualitatively different: while being almost independent of Mlin, K increases with Mring. This behavior could be realized in critical chromatography-for separation of partially cyclic polymers by the number and molar mass of cyclic elements. Copyright © 2015 Elsevier B.V. All rights reserved.

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

2014-07-01

... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Molar Exhaust Volumes and Molar Heat... Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent MEVa dscf/mol MHCb Btu/mol... standard conditions of 68 °F and 1 atmosphere. b MHC = molar heat content (higher heating value basis), Btu...

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

2013-07-01

... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Molar Exhaust Volumes and Molar Heat... Exhaust Volumes and Molar Heat Content of Fuel Gas Constituents Constituent MEVa dscf/mol MHCb Btu/mol... standard conditions of 68 °F and 1 atmosphere. b MHC = molar heat content (higher heating value basis), Btu...

Calculation of Derivative Thermodynamic Hydration and Aqueous Partial Molar Properties of Ions Based on Atomistic Simulations.

PubMed

Dahlgren, Björn; Reif, Maria M; Hünenberger, Philippe H; Hansen, Niels

2012-10-09

The raw ionic solvation free energies calculated on the basis of atomistic (explicit-solvent) simulations are extremely sensitive to the boundary conditions and treatment of electrostatic interactions used during these simulations. However, as shown recently [Kastenholz, M. A.; Hünenberger, P. H. J. Chem. Phys.2006, 124, 224501 and Reif, M. M.; Hünenberger, P. H. J. Chem. Phys.2011, 134, 144104], the application of an appropriate correction scheme allows for a conversion of the methodology-dependent raw data into methodology-independent results. In this work, methodology-independent derivative thermodynamic hydration and aqueous partial molar properties are calculated for the Na(+) and Cl(-) ions at P° = 1 bar and T(-) = 298.15 K, based on the SPC water model and on ion-solvent Lennard-Jones interaction coefficients previously reoptimized against experimental hydration free energies. The hydration parameters considered are the hydration free energy and enthalpy. The aqueous partial molar parameters considered are the partial molar entropy, volume, heat capacity, volume-compressibility, and volume-expansivity. Two alternative calculation methods are employed to access these properties. Method I relies on the difference in average volume and energy between two aqueous systems involving the same number of water molecules, either in the absence or in the presence of the ion, along with variations of these differences corresponding to finite pressure or/and temperature changes. Method II relies on the calculation of the hydration free energy of the ion, along with variations of this free energy corresponding to finite pressure or/and temperature changes. Both methods are used considering two distinct variants in the application of the correction scheme. In variant A, the raw values from the simulations are corrected after the application of finite difference in pressure or/and temperature, based on correction terms specifically designed for derivative parameters at P° and T(-). In variant B, these raw values are corrected prior to differentiation, based on corresponding correction terms appropriate for the different simulation pressures P and temperatures T. The results corresponding to the different calculation schemes show that, except for the hydration free energy itself, accurate methodological independence and quantitative agreement with even the most reliable experimental parameters (ion-pair properties) are not yet reached. Nevertheless, approximate internal consistency and qualitative agreement with experimental results can be achieved, but only when an appropriate correction scheme is applied, along with a careful consideration of standard-state issues. In this sense, the main merit of the present study is to set a clear framework for these types of calculations and to point toward directions for future improvements, with the ultimate goal of reaching a consistent and quantitative description of single-ion hydration thermodynamics in molecular dynamics simulations.

Molecular analysis of 16S rRNA genes identifies potentially periodontal pathogenic bacteria and archaea in the plaque of partially erupted third molars.

PubMed

Mansfield, J M; Campbell, J H; Bhandari, A R; Jesionowski, A M; Vickerman, M M

2012-07-01

Small subunit rRNA sequencing and phylogenetic analysis were used to identify cultivable and uncultivable microorganisms present in the dental plaque of symptomatic and asymptomatic partially erupted third molars to determine the prevalence of putative periodontal pathogens in pericoronal sites. Template DNA prepared from subgingival plaque collected from partially erupted symptomatic and asymptomatic mandibular third molars and healthy incisors was used in polymerase chain reaction with broad-range oligonucleotide primers to amplify 16S rRNA bacterial and archaeal genes. Amplicons were cloned, sequenced, and compared with known nucleotide sequences in online databases to identify the microorganisms present. Two thousand three hundred two clones from the plaque of 12 patients carried bacterial sequences from 63 genera belonging to 11 phyla, including members of the uncultivable TM7, SR1, and Chloroflexi, and difficult-to-cultivate Synergistetes and Spirochaetes. Dialister invisus, Filifactor alocis, Fusobacterium nucleatum, Porphyromonas endodontalis, Prevotella denticola, Tannerella forsythia, and Treponema denticola, which have been associated with periodontal disease, were found in significantly greater abundance in pericoronal compared with incisor sites. Dialister invisus and F nucleatum were found in greater abundance in sites exhibiting clinical symptoms. The archaeal species, Methanobrevibacter oralis, which has been associated with severe periodontitis, was found in 3 symptomatic patients. These findings have provided new insights into the complex microbiota of pericoronitis. Several bacterial and archaeal species implicated in periodontal disease were recovered in greater incidence and abundance from the plaque of partially erupted third molars compared with incisors, supporting the hypothesis that the pericoronal region may provide a favored niche for periodontal pathogens in otherwise healthy mouths. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Determination of thermodynamic properties of isotactic poly(1-butene) at infinite dilution using density and inverse gas chromatography.

PubMed

Kozłowska, Marta Karolina; Domańska, Urszula; Lempert, Małgorzata; Rogalski, Marek

2005-03-18

The partial molar volumes, V1(M), and the molar volume of isotactic crystalline low-molecular-weight poly(1-butene), iPBu-1, V1, have been calculated from the measured density of {iPBu-1 + solvent (n-hexane, n-heptane, n-nonane, n-decane, p-xylene, cyclohexane and chloroform)} systems. Some of the thermodynamic quantities were also obtained for the iPBu-1 with eight hydrocarbons (n-octane, n-decane, n-undecane, n-dodecane, n-tridecane, o-xylene, m-xylene, p-xylene) by the method of inverse gas chromatography at various temperatures. The weight fraction activity coefficients of the solvent at infinite dilution, omega2(infinity) and the Flory-Huggins thermodynamic interaction parameters, chi21(infinity), between polymer and solvents were determined. The partial molar free energy, deltaG2(infinity), the partial molar heat of mixing, deltaH2(infinity), at infinite dilution and the polymer solubility parameter, delta1, were calculated. Additionally, the (solid + liquid) binary mixtures equilibria, SLE, of iPBu-1 with three hydrocarbons (n-octane, n-decane and m-xylene) were studied by a dynamic method. By performing these experiments over a large concentration range, the T-x phase diagrams of the polymer-solvent systems were constructed. The excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase. The omega2(infinity) were determined from the solubility measurements and were predicted by using the UNIFAC FV model.

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

PubMed

Williams, Steven M; Ashbaugh, Henry S

2014-01-07

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Steven M.; Ashbaugh, Henry S., E-mail: hanka@tulane.edu

2014-01-07

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.

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

ERIC Educational Resources Information Center

Bedenbaugh, John H.; And Others

1988-01-01

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…

Ultrasonographic signs of partial hydatidiform mole.

PubMed

Muminhodzic, Lejla; Bogdanovic, Gordana

2013-01-01

This study aimed at investigating ultrasonographic features of partial hydatidiform mole to establish a proper diagnosis. This was a retrospective study of 70 pregnancies which were divided into two groups: group I--35 pregnant women with a molar pregnancy diagnosed in the first trimester; group II--35 pregnant women with physiological pregnancy spontaneously aborted in the first trimester caused by the cervical insufficiency. Evacuation of the uterus by uterine suction or curettage and pathomorphological analysis ofovular tissue were conducted in both groups. Ultrasonographic parameters were analyzed. Theca lutein cysts and hydropic degeneration of villi, enlarged uterus and empty gestational sac, intrauterine hematoma significantly prevailed in the pregnant women with the molar pregnancies. Diagnosis of the partial hydatidiform mole in the first trimester is likely though not enough reliable. Thereby, additional diagnostic methods might be important as well to confirm an early diagnosis of mole.

Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karles Fellowship

DTIC Science & Technology

2015-11-30

water (DI H2O) as the reference solution, two concentrations of NaCl mixtures (0.6 Molar, and 1.0 Molar saturated NaCl), and three electroless solutions...by diffusion) to the bulk surface in net excess; that oxygen ions/radicals are being consumed from the bulk by an electrolysis path way; or that the

Interpretations of complications following third molar extraction.

PubMed

Schwartz-Arad, Devorah; Lipovsky, Anat; Pardo, Michal; Adut, Oren; Dolev, Eran

2017-11-21

Surgical removal of third molars is often associated with complications. The aim of the present study was to analyze the incidence of complications following extraction of third molars relative to the risk factors. This retrospective study included 463 patients who had mandibular third molar extraction (performed by a single surgeon, DSA) in the years 2001 to 2011. In total, 665 mandibular third molars were extracted. The average patient's age was 29 ± 11.30 years, median 26 years, and the patient age ranged from 13 to 75 years. Patients' records were obtained for medical/general data. The overall prevalence of postsurgical complications was 17%. Dry sockets showed the highest incidence (11.6%). Partially impacted teeth showed the highest incidence of complications (67.3%). Cigarette smoking correlated with increased complications and dry sockets, and complications were more prevalent on the left side (62.8%). Complications after mandibular third molar extraction increase with age, level of impaction, side of extraction, and cigarette smoking.

Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin

PubMed Central

Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

2007-01-01

The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier. PMID:17660257

Theoretical study of the partial molar volume change associated with the pressure-induced structural transition of ubiquitin.

PubMed

Imai, Takashi; Ohyama, Shusaku; Kovalenko, Andriy; Hirata, Fumio

2007-09-01

The partial molar volume (PMV) change associated with the pressure-induced structural transition of ubiquitin is analyzed by the three-dimensional reference interaction site model (3D-RISM) theory of molecular solvation. The theory predicts that the PMV decreases upon the structural transition, which is consistent with the experimental observation. The volume decomposition analysis demonstrates that the PMV reduction is primarily caused by the decrease in the volume of structural voids in the protein, which is partially canceled by the volume expansion due to the hydration effects. It is found from further analysis that the PMV reduction is ascribed substantially to the penetration of water molecules into a specific part of the protein. Based on the thermodynamic relation, this result implies that the water penetration causes the pressure-induced structural transition. It supports the water penetration model of pressure denaturation of proteins proposed earlier.

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

PubMed

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

2014-06-05

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 approximation for the free-energy functional, the so-called homogeneous reference fluid approximation, we show that the hydration free-energies computed for a data set of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by 2-3 orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canonical 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 justification to empirical partial molar volume corrections that have been proposed recently.

Efficacy of orally administered prednisolone versus partial endodontic treatment on pain reduction in emergency care of acute irreversible pulpitis of mandibular molars: study protocol for a randomized controlled trial.

PubMed

Kérourédan, Olivia; Jallon, Léonard; Perez, Paul; Germain, Christine; Péli, Jean-François; Oriez, Dominique; Fricain, Jean-Christophe; Arrivé, Elise; Devillard, Raphaël

2017-03-28

Irreversible pulpitis is a highly painful inflammatory condition of the dental pulp which represents a common dental emergency. Recommended care is partial endodontic treatment. The dental literature reports major difficulties in achieving adequate analgesia to perform this emergency treatment, especially in the case of mandibular molars. In current practice, short-course, orally administered corticotherapy is used for the management of oral pain of inflammatory origin. The efficacy of intraosseous local steroid injections for irreversible pulpitis in mandibular molars has already been demonstrated but resulted in local comorbidities. Oral administration of short-course prednisolone is simple and safe but its efficacy to manage pain caused by irreversible pulpitis has not yet been demonstrated. This trial aims to evaluate the noninferiority of short-course, orally administered corticotherapy versus partial endodontic treatment for the emergency care of irreversible pulpitis in mandibular molars. This study is a noninferiority, open-label, randomized controlled clinical trial conducted at the Bordeaux University Hospital. One hundred and twenty subjects will be randomized in two 1:1 parallel arms: the intervention arm will receive one oral dose of prednisolone (1 mg/kg) during the emergency visit, followed by one morning dose each day for 3 days and the reference arm will receive partial endodontic treatment. Both groups will receive planned complete endodontic treatment 72 h after enrollment. The primary outcome is the proportion of patients with pain intensity below 5 on a Numeric Scale 24 h after the emergency visit. Secondary outcomes include comfort during care, the number of injected anesthetic cartridges when performing complete endodontic treatment, the number of antalgic drugs and the number of patients coming back for consultation after 72 h. This randomized trial will assess the ability of short-term corticotherapy to reduce pain in irreversible pulpitis as a simple and rapid alternative to partial endodontic treatment and to enable planning of endodontic treatment in optimal analgesic conditions. ClinicalTrials.gov, identifier: NCT02629042 . Registered on 7 December 2015. (Version n°1.1 28 July 2015).

Occlusion and Temporomandibular Function among Subjects with Mandibular Distal Extension Removable Partial Dentures

PubMed Central

Creugers, N. H. J.; Witter, D. J.; Van 't Spijker, A.; Gerritsen, A. E.; Kreulen, C. M.

2010-01-01

Objective. To quantify effects on occlusion and temporomandibular function of mandibular distal extension removable partial dentures in shortened dental arches. Methods. Subjects wearing mandibular extension removable partial dentures (n = 25) were compared with subjects with shortened dental arches without extension (n = 74) and with subjects who had worn a mandibular extension removable partial denture in the past (n = 19). Subjects with complete dentitions (n = 72) were controls. Data were collected at baseline and at 3-, 6-, and 9-year observations. Results. Occlusal activity in terms of reported awareness of bruxism and occlusal tooth wear of lower anterior teeth did not differ significantly between the groups. In contrast, occlusal tooth wear of premolars in shortened dental arches with or without extension dentures was significantly higher than in the controls. Differences amongst groups with respect to signs and symptoms related to temporomandibular disorders were not found. Occlusal support of the dentures did not influence anterior spatial relationship. Occlusal contacts of the denture teeth decreased from 70% for second premolars via 50% for first molars, to 30% for second molars. Conclusions. Mandibular distal extension removable partial dentures in moderate shortened dental arches had no effects on occlusion and temporomandibular function. PMID:20671961

Entropy of adsorption of mixed surfactants from solutions onto the air/water interface

USGS Publications Warehouse

Chen, L.-W.; Chen, J.-H.; Zhou, N.-F.

1995-01-01

The partial molar entropy change for mixed surfactant molecules adsorbed from solution at the air/water interface has been investigated by surface thermodynamics based upon the experimental surface tension isotherms at various temperatures. Results for different surfactant mixtures of sodium dodecyl sulfate and sodium tetradecyl sulfate, decylpyridinium chloride and sodium alkylsulfonates have shown that the partial molar entropy changes for adsorption of the mixed surfactants were generally negative and decreased with increasing adsorption to a minimum near the maximum adsorption and then increased abruptly. The entropy decrease can be explained by the adsorption-orientation of surfactant molecules in the adsorbed monolayer and the abrupt entropy increase at the maximum adsorption is possible due to the strong repulsion between the adsorbed molecules.

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars.

PubMed

Acar, Buket; Kamburoğlu, Kıvanç; Tatar, İlkan; Arıkan, Volkan; Çelik, Hakan Hamdi; Yüksel, Selcen; Özen, Tuncer

2015-12-01

This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

Size-exclusion chromatography of perfluorosulfonated ionomers.

PubMed

Mourey, T H; Slater, L A; Galipo, R C; Koestner, R J

2011-08-26

A size-exclusion chromatography (SEC) method in N,N-dimethylformamide containing 0.1 M LiNO(3) is shown to be suitable for the determination of molar mass distributions of three classes of perfluorosulfonated ionomers, including Nafion(®). Autoclaving sample preparation is optimized to prepare molecular solutions free of aggregates, and a solvent exchange method concentrates the autoclaved samples to enable the use of molar-mass-sensitive detection. Calibration curves obtained from light scattering and viscometry detection suggest minor variation in the specific refractive index increment across the molecular size distributions, which introduces inaccuracies in the calculation of local absolute molar masses and intrinsic viscosities. Conformation plots that combine apparent molar masses from light scattering detection with apparent intrinsic viscosities from viscometry detection partially compensate for the variations in refractive index increment. The conformation plots are consistent with compact polymer conformations, and they provide Mark-Houwink-Sakurada constants that can be used to calculate molar mass distributions without molar-mass-sensitive detection. Unperturbed dimensions and characteristic ratios calculated from viscosity-molar mass relationships indicate unusually free rotation of the perfluoroalkane backbones and may suggest limitations to applying two-parameter excluded volume theories for these ionomers. Copyright © 2011 Elsevier B.V. All rights reserved.

A Survey of Removable Partial Denture (RPD) Retentive Elements in Relation to the Type of Edentulism and Abutment Teeth Found in Commercial Laboratories, Athens, Greece

PubMed Central

Sotiriou, Michael; Zissis, Alcibiades

2014-01-01

Objective The aim of this survey was to record removable partial denture (RPD) retentive elements and abutment teeth in partially edentulous patients, identified in commercial laboratories in Athens, Greece. Material and Methods 628 master casts with the corresponding cast metal frameworks used in the construction of RPDs were evaluated. Casts were photographed to identify the number and position of existing teeth, the partial edentulism class and the retentive elements. Prevalence tables and the x2 test were used for the statistical analysis of the collected data (α=.05). Results There were 276 maxillary (43.9%) and 352 (56.1%) mandibular casts. Maxillary edentulism entailed almost a total absence of right third molars in 96.7% and left third molars 96.0% of casts, with lower rates for the first and second molars. Edentulism in the posterior mandible presented a similar pattern. The most profound findings concerning retentive elements were: 91.9% of the retainers used were clasps and the remaining 8.1% were attachments. Of the clasps used, 48.9% were of the Roach Τ type, a finding more common in Kennedy Class I as compared to other Kennedy Classes (p<0.01). The circumferential clasps accounted for 19.3% of the total clasps used, and it was less frequently presented (8.8%) in Kennedy I Classes (p<0.01). Conclusions Roach clasps were used in the majority of cases whereas RPI clasps and attachments were rarely used. PMID:27688367

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Ming-Liang; Te, Jerez; Cendagorta, Joseph R.

2015-02-14

The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol V{sub E} as a function of ethanol mole fraction X{sub E} is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decreasemore » 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.« less

Elasticity-driven partial demixing in cholesteric liquid crystal films.

PubMed

Schmidtke, Jürgen; Coles, Harry J

2009-07-01

We discuss the partial demixing of a chiral nematic mixture of a chiral and an achiral compound, induced by inhomogeneous confinement between substrates. While the effect is tiny in low molar mass mixtures, it is predicted to be noticeable in polymeric systems. The potential of the effect for improving performance of liquid crystal based photonic devices is discussed.

Pressure effects on the structure, kinetic, and thermodynamic properties of heat-induced aggregation of protein studied by FT-IR spectroscopy

NASA Astrophysics Data System (ADS)

Taniguchi, Y.; Okuno, A.; Kato, M.

2010-03-01

Pressure can retrain the heat-induced aggregation and dissociate the heat-induced aggregates. We observed the aggregation-preventing pressure effect and the aggregates-dissociating pressure effect to characterize the heat-induced aggregation of equine serum albumin (ESA) by FT-IR spectroscopy. The results suggest the α-helical structure collapses at the beginning of heat-induced aggregation through the swollen structure, and then the rearrangement of structure to the intermolecular β-sheet takes place through partially unfolded structure. We determined the activation volume for the heat-induced aggregation (ΔV# = +93 ml/mol) and the partial molar volume difference between native state and heat-induced aggregates (ΔV=+32 ml/mol). This positive partial molar volume difference suggests that the heat-induced aggregates have larger internal voids than the native structure. Moreover, the positive volume change implies that the formation of the intermolecular β-sheet is unfavorable under high pressure.

QSPR models for various physical properties of carbohydrates based on molecular mechanics and quantum chemical calculations.

PubMed

Dyekjaer, Jane Dannow; Jónsdóttir, Svava Osk

2004-01-22

Quantitative Structure-Property Relationships (QSPR) have been developed for a series of monosaccharides, including the physical properties of partial molar heat capacity, heat of solution, melting point, heat of fusion, glass-transition temperature, and solid state density. The models were based on molecular descriptors obtained from molecular mechanics and quantum chemical calculations, combined with other types of descriptors. Saccharides exhibit a large degree of conformational flexibility, therefore a methodology for selecting the energetically most favorable conformers has been developed, and was used for the development of the QSPR models. In most cases good correlations were obtained for monosaccharides. For five of the properties predictions were made for disaccharides, and the predicted values for the partial molar heat capacities were in excellent agreement with experimental values.

Pathological (late) fractures of the mandibular angle after lower third molar removal: a case series.

PubMed

Cutilli, Tommaso; Bourelaki, Theodora; Scarsella, Secondo; Fabio, Desiderio Di; Pontecorvi, Emanuele; Cargini, Pasqualino; Junquera, Luis

2013-04-30

Pathological (late) fracture of the mandibular angle after third molar surgery is very rare (0.005% of third molar removals). There are 94 cases reported in the literature; cases associated with osseous pathologies such as osteomyelitis or any local and systemic diseases that may compromise mandibular bone strength have not been included. We describe three new cases of pathological (late) fracture of the mandibular angle after third molar surgery. The first patient was a 27-year-old Caucasian man who had undergone surgical removal of a 3.8, mesioangular variety, class II-C third molar 20 days before admission to our clinic. The fracture of his left mandibular angle, complete and composed, occurred during chewing. The second patient was a 32-year-old Caucasian man. He had undergone surgical removal of a 3.8, mesioangular variety, class II-B third molar 22 days before his admission. The fracture, which occurred during mastication, was studied by computed tomography that showed reparative tissue in the fracture site. The third patient was a 36-year-old Caucasian man who had undergone surgical removal of a 3.8, vertical variety, class II-C third molar 25 days before the observation. In this case the fracture of his mandibular angle was oblique (unfavorable), complete and composed. The fracture had occurred during chewing. We studied the fracture by optical projection tomography and computed tomography.All of the surgical removals of the 3.8 third molars, performed by the patients' dentists who had more than 10 years of experience, were difficult. We treated the fractures with open surgical reduction, internal fixation by titanium miniplates and intermaxillary elastic fixation removed after 6 weeks. The literature indicates that the risk of pathological (late) fracture of the mandibular angle after third molar surgery for total inclusions (class II-III, type C) is twice that of partial inclusions due to the necessity of ostectomies more generous than those for partial inclusions. Other important factors are the anatomy of the teeth and the features of the teeth roots. These fractures predominantly occur in patients who are older than 25 years. The highest incidence (67.8% of cases) is found in the second and third week postsurgery. We emphasize that before the third molar surgery it is extremely important to always provide adequate instructions to the patient in order to avoid early masticatory loads and prevent this rare event.

Solvation behaviour of L-leucine in aqueous ionic liquid at different temperatures: Volumetric approach

NASA Astrophysics Data System (ADS)

Sharma, Samriti; Sandarve, Sharma, Amit K.; Sharma, Meena

2018-05-01

For the investigation of interactions of L-leucine in aqueous solutions of an ionic liquid (1-butyl-3-methylimidazolium tetra fluoroborate [Bmim][BF4]) at atmospheric pressure over a temperature range of (293.15K to 313.16K), we use the volumetric approach. By using the density data we have calculated the apparent molar volume, VΦ, limiting apparent molar volume, V0Φ, the slope, Sv, partial molar volume of transfer, V0Φ,tr. The values of these acoustical parameters have been used for the interpretation of different interactions like hydrophilic-hydrophilic, hydrophilic-hydrophobic, ion hydrophilic, solute-solvent and solute-solute interactions in the amino acid and ionic liquid solutions.

The in vitro effect of Antimicrobial Photodynamic Therapy on dental microcosm biofilms from partially erupted permanent molars: A pilot study.

PubMed

de Oliveira, Fabiana Sodré; Cruvinel, Thiago; Cusicanqui Méndez, Daniela Alejandra; Dionísio, Evandro José; Rios, Daniela; Machado, Maria Aparecida Andrade Moreira

2018-03-01

Antimicrobial Photodynamic Therapy (aPDT) could enhance the prevention of dental caries lesions in pits and fissures of partially erupted molars, by killing microorganisms from complex dental biofilms. This pilot study aimed to evaluate the effect of Antimicrobial Photodynamic Therapy (aPDT) on the viability of specific microorganism groups of dental microcosm biofilms from occlusal surfaces of first permanent molars in eruption. Dental microcosm biofilms grown on bovine enamel blocks, from dental plaque collected on occlusal surfaces of a partially erupted lower right first permanent molar, with McBain medium plus 1% sucrose in anaerobic condition at 37 °C for 72 h. The experiments were performed in eight groups: L-P- = no treatment (control), L18.75P- = 18.75 J/cm 2 LED, L37.5P- = 37.5 J/cm 2 LED, L75P- = 75 J/cm 2 LED, L-P+ = 200 mM TBO, L18.75P+ = 200 mM TBO + 18.75 J/cm 2 LED, L37.5P+ = 200 mM TBO + 37.5 J/cm 2 LED, and L75P+ = 200 mM TBO + 75 J/cm 2 LED. The counts of total microorganisms, total streptococci and mutans streptococci were determined on selective media agar plates by colony-forming units per mL. The log-transformed counts were analyzed by Kruskal-Wallis and post-hoc Dunn's test (P < 0.05). The counts of all microorganisms treated in the group L75P+ were statistically lower than those treated in L-P-. The aPDT promoted a significant reduction of microorganisms, with a trend of dose-dependent effect. TBO-mediated aPDT was effective in reducing the viability of specific microbial groups in dental microcosm biofilms originated from occlusal of permanent molars in eruption. Copyright © 2017 Elsevier B.V. All rights reserved.

Molar volume and adsorption isotherm dependence of capillary forces in nanoasperity contacts.

PubMed

Asay, David B; Kim, Seong H

2007-11-20

The magnitude of the capillary force at any given temperature and adsorbate partial pressure depends primarily on four factors: the surface tension of the adsorbate, its liquid molar volume, its isothermal behavior, and the contact geometry. At large contacting radii, the adsorbate surface tension and the contact geometry are dominating. This is the case of surface force apparatus measurements and atomic force microscopy (AFM) experiments with micrometer-size spheres. However, as the size of contacting asperities decreases to the nanoscale as in AFM experiments with sharp tips, the molar volume and isotherm of the adsorbate become very important to capillary formation as well as capillary adhesion. This effect is experimentally and theoretically explored with simple alcohol molecules (ethanol, 1-butanol, and 1-pentanol) which have comparable surface tensions but differing liquid molar volumes. Adsorption isotherms for these alcohols on silicon oxide are also reported.

Endodontic treatment of a fused tooth. Report of a case.

PubMed

Gallottini, L; Barbato Bellatini, R C; Migliau, G

2007-01-01

Dental fusion, a rare developmental anomaly present in 0.2% of the general population, consists of the union of two teeth originating from two different tooth germs. The irregular coronal morphology and the complex endodontic anatomy, characterized by the partial or total union of the pulp chambers, together with the peculiarity of the root canal systems, make diagnosis, therapy and rehabilitation difficult. The authors describe the endodontic treatment of a permanent lower second molar fused with a third molar and having four root canals.

Stress distribution of various designs of prostheses on short implants or standard implants in posterior maxilla: a three dimensional finite element analysis

PubMed Central

JOMJUNYONG, K.; RUNGSIYAKULL, P.; RUNGSIYAKULL, C.; AUNMEUNGTONG, W.; CHANTARAMUNGKORN, M.; KHONGKHUNTHIAN, P.

2017-01-01

SUMMARY Introduction. Although many previous studies have reported on the high success rate of short dental implants, prosthetic design still plays an important role in the long-term implant treatment results. This study aims to evaluate stress distribution characteristics involved with various prosthetic designs on standard implants or short implants in the posterior maxilla. Materials and methods. Six finite element models were simulated representing the missing first and second maxillary molars. A standard implant (PW+ implant: 5.0×10 mm) and a short implant (PW+ implant: 5.0×6.0 mm) were applied under the various prosthetic conditions. The peri-implant maximum bone stress (V on mises stress) was evaluated when 200 N 30° oblique load was applied. A type III bone was approximated and complete osseous integration was assumed. Results. Maximum Von mises stress was numerically located at the cortical bone around the implant neck in all models. In every standard implant model shows better stress distribution. Stress values and concentration area decreased in the cortical and cancellous bone when implants were splinted in both the standard and short implant models. With regard to the non-replacing second molar models found that the area of stress at the cortical bone around the first molar implant to be more intensive. Moreover, in the non-replacing second molar models, the stress also spread to the second pre-molar in both the standard and short implant models. Conclusions. The length of the implant and prosthetics designs both affect the stress value and distribution of stress to the cortical and cancellous bones around the implant. PMID:29682254

A prospective study on transplantation of third molars with complete root formation.

PubMed

Mejàre, Bertil; Wannfors, Karin; Jansson, Leif

2004-02-01

The study objective was to evaluate the prognosis for autotransplantation of third molar teeth with fully developed roots followed by endodontic treatment on the basis of a time-table analysis. A total of 50 third molars with completely developed roots were autotransplanted to replace a lost first or second molar in the same number of admitted patients. Root canal treatment was started 3 to 4 weeks later. Clinical and radiographic checkup of the transplanted and root-filled third molars was done annually according to a predesigned record form. Descriptive statistics including a life table and statistical analysis were performed. The cumulative survival rate during 4 years' follow-up was 81.4%. In all, 7 transplants were lost during the follow-up time, 4 of them due to marginal periodontal pathosis and the other 3 due to root resorption. None of the root resorptions was observed before the second postoperative year. The radiographic periapical status was considered normal in 96% of the transplants at the latest follow-up visit. Autotransplantation of mature third molar teeth is a reasonable treatment alternative to conventional prosthetic rehabilitation or implant treatment in cases of partial edentualism from both a therapeutic and an economic point of view.

Effect of isotretinoin on tooth germ and palate development in mouse embryos.

PubMed

Balducci-Roslindo, E; Silvério, K G; Jorge, M A; Gonzaga, H F

2001-01-01

Vitamin A and its derivatives, retinoic acid, tretinoin and isotretinoin, are currently used in dermatological treatments. The administration of high doses of this vitamin provokes congenital malformations in mice: cleft palate, maxillary and mandibular hypoplasia and total or partial fusion of the maxillary incisors. This study compares the tooth germs of the first maxillary and mandibular molars of fetal mice submitted to isotretinoin during organogenesis. Twelve 60-day-old female Mus musculus were divided into two groups on the 7th day of pregnancy: treated group--1 mg isotretinoin per kg body weight, dissolved in vegetable oil, was administered from the 7th to the 13th day of pregnancy; control group--vegetable oil in equivalent volume was administered orally for the same period. On the 16th day of pregnancy, the females were sacrificed, the fetuses were removed and their heads amputated. After standard laboratory procedures, 6-micron thick serial slices were stained with hematoxylin and eosin for optical microscopy examination. The results showed that both groups had closed palates with no reminiscence of epithelial cells; however, the first molar germs of the isotretinoin-treated animals showed delayed development compared to the control animals.

Metric and geometric morphometric analysis of new hominin fossils from Maba (Guangdong, China).

PubMed

Xiao, Dongfang; Bae, Christopher J; Shen, Guanjun; Delson, Eric; Jin, Jennie J H; Webb, Nicole M; Qiu, Licheng

2014-09-01

We present an analysis of a set of previously unreported hominin fossils from Maba (Guangdong, China), a cave site that is best known for the presence of a partial hominin cranium currently assigned as mid-Pleistocene Homo and that has been traditionally dated to around the Middle-Late Pleistocene transition. A more recent set of Uranium series dates indicate that the Maba travertine may date to >237 ka (thousands of years ago), as opposed to the original U-series date, which placed Maba at 135-129 ka. The fossils under study include five upper first and second molars and a partial left mandible with a socketed m3, all recovered from different parts of the site than the cranium or the dated sediments. The results of our metric and 2D geometric morphometric ('GM') study suggest that the upper first molars are likely from modern humans, suggesting a more recent origin. The upper second molars align more closely with modern humans, though the minimum spanning tree from the 2D GM analysis also connects Maba to Homo neanderthalensis. The patterning in the M2s is not as clear as with the M1s. The m3 and partial mandible are morphometrically intermediate between Holocene modern humans and older Homo sapiens. However, a minimum spanning tree indicates that both the partial mandible and m3 align most closely with Holocene modern humans, and they also may be substantially younger than the cranium. Because questions exist regarding the context and the relationship of the dated travertine with the hominin fossils, we suggest caution is warranted in interpreting the Maba specimens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Melt densities in the CaO-FeO-Fe 2O 3-SiO 2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts

NASA Astrophysics Data System (ADS)

Dingwell, Donald B.; Brearley, Mark

1988-12-01

The densities of 10 melts in the CaO-FeO-Fe 2O 3-SiO 2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO 2, 14 to 76 wt% Fe 2O 3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy. Melt densities range from 2.689 to 3.618 gm/cm 3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe 2O 3 and SiO 2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe 3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe 3+. The volume behavior of melts in this system is significantly different from that in the Na 2O-FeO-Fe 2O 3-SiO 2 system, consistent with the proposal that a proportion of Fe 3+ in melts in the CaO-FeO-Fe 2O 3-SiO 2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence ( e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations. The presence of more than one coordination geometry for Fe 3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted.

Experimental and computational thermochemical study of α-alanine (DL) and β-alanine.

PubMed

da Silva, Manuel A V Ribeiro; da Silva, Maria das Dores M C Ribeiro; Santos, Ana Filipa L O M; Roux, Maria Victoria; Foces-Foces, Concepción; Notario, Rafael; Guzmán-Mejía, Ramón; Juaristi, Eusebio

2010-12-16

This paper reports an experimental and theoretical study of the gas phase standard (p° = 0.1 MPa) molar enthalpies of formation, at T = 298.15 K, of α-alanine (DL) and β-alanine. The standard (p° = 0.1 MPa) molar enthalpies of formation of crystalline α-alanine (DL) and β-alanine were calculated from the standard molar energies of combustion, in oxygen, to yield CO2(g), N2(g), and H2O(l), measured by static-bomb combustion calorimetry at T = 298.15 K. The vapor pressures of both amino acids were measured as function of temperature by the Knudsen effusion mass-loss technique. The standard molar enthalpies of sublimation at T = 298.15 K was derived from the Clausius−Clapeyron equation. The experimental values were used to calculate the standard (p° = 0.1 MPa) enthalpy of formation of α-alanine (DL) and β-alanine in the gaseous phase, Δ(f)H(m)°(g), as −426.3 ± 2.9 and −421.2 ± 1.9 kJ·mol(−1), respectively. Standard ab initio molecular orbital calculations at the G3 level were performed. Enthalpies of formation, using atomization reactions, were calculated and compared with experimental data. Detailed inspections of the molecular and electronic structures of the compounds studied were carried out.

Effect of race/ethnicity on clinical presentation and risk of gestational trophoblastic neoplasia in patients with complete and partial molar pregnancy at a tertiary care referral center.

PubMed

Gockley, Allison A; Joseph, Naima T; Melamed, Alexander; Sun, Sue Yazaki; Goodwin, Benjamin; Bernstein, Marilyn; Goldstein, Donald P; Berkowitz, Ross S; Horowitz, Neil S

2016-09-01

The reported incidence of molar pregnancy varies widely among different geographic locations. This variation has been attributed, at least in part, to racial/ethnic differences. While the incidence of molar pregnancies is decreasing, certain ethnic groups such as Hispanics, Asians, and American Indians continue to have an increased risk of developing gestational trophoblastic disease across the globe. We sought to describe the potential effect of ethnicity/race on the presentation and clinical course of complete mole and partial mole. All patients followed up for complete mole and partial mole at a single institution referral center from 1994 through 2013 were identified. Variables including age, race, gravidity, parity, gestational age, presenting signs/symptoms, serum human chorionic gonadotropin values, and development of gestational trophoblastic neoplasia were extracted from medical records and patient surveys. Patients with complete mole and partial mole were categorized into race/ethnicity groups defined as white, black, Asian, or Hispanic. Due to low numbers of non-white patients with partial mole in each non-white category, patients with partial mole were grouped as white or non-white. Continuous variables were compared using the Kruskal-Wallis test and binary variables were compared using the Fisher exact test. A total of 167 complete mole patients with known race/ethnicity status were included (57.48% white, 14.97% Asian, 14.37% black, 13.17% Hispanic). Hispanics presented at younger age (median 24.5 years) compared to whites (median 32.0 years, P = .04) and Asians (median 31.0 years, P = .03). Blacks had higher gravidity than whites (P < .001) and Hispanics (P = .05). There was no significant difference in presenting symptoms, gestational age at diagnosis, and preevacuation serum human chorionic gonadotropin level by race/ethnicity. Hispanics were significantly less likely than whites to develop gestational trophoblastic neoplasia (absolute risk difference, 28.6%; 95% confidence interval, 8.1-39.2%; P = .02). A total of 144 patients with partial mole were analyzed. There were 108 white and 36 non-white patients. Median age was 31 years for white and 29 years for non-white patients (P = .006). Median gravidity was 2 for white and 3 for non-white patients (P < .001), and median parity was 0 for white patients and 1 for non-white patients (P = .003). There were no significant differences with respect to presenting signs and symptoms, gestational age, preevacuation human chorionic gonadotropin level, or risk of progression to gestational trophoblastic neoplasia. Hispanic patients with complete molar pregnancy had a significantly lower risk of developing gestational trophoblastic neoplasia than white patients. There were no significant differences among groups in terms of presenting symptoms, gestational age at diagnosis, or preevacuation human chorionic gonadotropin levels for either complete mole or partial mole patients. Copyright © 2016. Published by Elsevier Inc.

Accuracy of the vertical tube shift method in identifying the relationship between the third molars and the mandibular canal.

PubMed

de-Azevedo-Vaz, Sergio Lins; Oenning, Anne Caroline Costa; Felizardo, Marcela Graciano; Haiter-Neto, Francisco; de Freitas, Deborah Queiroz

2015-04-01

The objective of this study is to assess the accuracy of the vertical tube shift method in identifying the relationship between the mandibular canal (MC) and third molars. Two examiners assessed image sets of 173 lower third molar roots (55 patients) using forced consensus. The image sets comprised two methods: PERI, two periapical radiographs (taken at 0° and -30°), and PAN, a panoramic radiograph (vertical angulation of -8°) and a periapical radiograph taken at a vertical angulation of -30°. Cone beam computed tomography (CBCT) was the reference standard in the study. The responses were recorded for position (buccal, in-line with apex and lingual) and contact (present or absent). The McNemar-Bowker and McNemar tests were used to determine if the PERI and PAN methods would disagree with the reference standard (α = 5 %). The PERI and PAN methods disagreed with the reference standard for both position and contact (p < 0.05). The vertical tube shift method was not accurate in determining the relationship between lower third molars and the MC. The vertical tube shift is not a reliable method for predicting the relationship between lower third molars and the MC.

Thermodynamic studies of aqueous and CCl4 solutions of 15-crown-5 at 298.15 K: an application of McMillan-Mayer and Kirkwood-Buff theories of solutions.

PubMed

Dagade, Dilip H; Shetake, Poonam K; Patil, Kesharsingh J

2007-07-05

The density and osmotic coefficient data for solutions of 15-crown-5 (15C5) in water and in CCl4 solvent systems at 298.15 K have been reported using techniques of densitometry and vapor pressure osmometry in the concentration range of 0.01-2 mol kg-1. The data are used to obtain apparent molar and partial molar volumes, activity coefficients of the components as a function of 15C5 concentration. Using the literature heat of dilution data for aqueous system, it has become possible to calculate entropy of mixing (DeltaS(mix)), excess entropy of solution (DeltaS(E)), and partial molar entropies of the components at different concentrations. The results of all these are compared to those obtained for aqueous 18-crown-6 solutions reported earlier. It has been observed that the partial molar volume of 15C5 goes through a minimum and that of water goes through a maximum at approximately 1.2 mol kg(-1) in aqueous solutions whereas the opposite is true in CCl4 medium but at approximately 0.5 mol kg(-1). The osmotic and activity coefficients of 15C5 and excess free energy change for solution exhibit distinct differences in the two solvent systems studied. These results have been explained in terms of hydrophobic hydration and interactions in aqueous solution while weak solvophobic association of 15C5 molecules in CCl4 solutions is proposed. The data are further subjected to analysis by applying McMillan-Mayer and Kirkwood-Buff theories of solutions. The analysis shows that osmotic second virial coefficient value for 15C5 is marginally less than that of 18C6 indicating that reduction in ring flexibility does not affect the energetics of the interactions much in aqueous solution while the same gets influenced much in nonpolar solvent CCl4.

Molecular simulation of excess isotherm and excess enthalpy change in gas-phase adsorption.

PubMed

Do, D D; Do, H D; Nicholson, D

2009-01-29

We present a new approach to calculating excess isotherm and differential enthalpy of adsorption on surfaces or in confined spaces by the Monte Carlo molecular simulation method. The approach is very general and, most importantly, is unambiguous in its application to any configuration of solid structure (crystalline, graphite layer or disordered porous glass), to any type of fluid (simple or complex molecule), and to any operating conditions (subcritical or supercritical). The behavior of the adsorbed phase is studied using the partial molar energy of the simulation box. However, to characterize adsorption for comparison with experimental data, the isotherm is best described by the excess amount, and the enthalpy of adsorption is defined as the change in the total enthalpy of the simulation box with the change in the excess amount, keeping the total number (gas + adsorbed phases) constant. The excess quantities (capacity and energy) require a choice of a reference gaseous phase, which is defined as the adsorptive gas phase occupying the accessible volume and having a density equal to the bulk gas density. The accessible volume is defined as the mean volume space accessible to the center of mass of the adsorbate under consideration. With this choice, the excess isotherm passes through a maximum but always remains positive. This is in stark contrast to the literature where helium void volume is used (which is always greater than the accessible volume) and the resulting excess can be negative. Our definition of enthalpy change is equivalent to the difference between the partial molar enthalpy of the gas phase and the partial molar enthalpy of the adsorbed phase. There is no need to assume ideal gas or negligible molar volume of the adsorbed phase as is traditionally done in the literature. We illustrate this new approach with adsorption of argon, nitrogen, and carbon dioxide under subcritical and supercritical conditions.

Effects of first molar extraction on third molar angulation and eruption space.

PubMed

Bayram, Mehmet; Ozer, Mete; Arici, Selim

2009-02-01

The aim was to investigate the effects of orthodontic treatment with 4 first molar extractions on the angulations and eruption spaces of all third molars and to compare these changes with outcomes of nonextraction samples used as a control group. This study was carried out on standardized panoramic radiographs of 41 subjects (8 male, 33 female) with a mean age of 16.6 years (range 13 to 20 years). Twenty-one of the subjects were orthodontically treated with extraction of the 4 first permanent molars, and 20 had nonextraction treatment. The angulational changes and eruption spaces of third molars were evaluated on the panoramic radiographs taken before treatment and at the end of the observation period. Analysis of the linear variables demonstrated a statistically significant difference between the 2 groups for all third molar eruption spaces (P < .001). The mean differences in the third molar eruption spaces between the pretreatment and posttreatment values for the first molar extraction group were higher than those of the nonextraction cases. Orthodontic treatment accomplished with extractions of the permanent first molars increases the eruption spaces of third molars and decreases their impaction. In addition, it has greater favorable effect on the angulation of the upper third molars than of the lower third molars.

Molar heat capacity and entropy of calcium metal

USGS Publications Warehouse

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

1997-01-01

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

Organic carbonates: experiment and ab initio calculations for prediction of thermochemical properties.

PubMed

Verevkin, Sergey P; Emel'yanenko, Vladimir N; Kozlova, Svetlana A

2008-10-23

This work has been undertaken in order to obtain data on thermodynamic properties of organic carbonates and to revise the group-additivity values necessary for predicting their standard enthalpies of formation and enthalpies of vaporization. The standard molar enthalpies of formation of dibenzyl carbonate, tert-butyl phenyl carbonate, and diphenyl carbonate were measured using combustion calorimetry. Molar enthalpies of vaporization of these compounds were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. Molar enthalpy of sublimation of diphenyl carbonate was measured in the same way. Ab initio calculations of molar enthalpies of formation of organic carbonates have been performed using the G3MP2 method, and results are in excellent agreement with the available experiment. Then the group-contribution method has been developed to predict values of the enthalpies of formation and enthalpies of vaporization of organic carbonates.

The Partial Molar Volume and Compressibility of FeO in CaO-SiO2 Liquids: Systematic Variation with Fe2+ Coordination Change

NASA Astrophysics Data System (ADS)

Guo, X.; Lange, R. A.; Ai, Y.

2009-12-01

Iron is an important element in magmatic liquid, since its concentration can range up to 18% in some basaltic liquids, and it has two oxidation states. In order to model magmatic processes, thermodynamic descriptions of silicate melts must include precise information for both the FeO and Fe2O3 components. Currently, the partial molar volume of FeO is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Yet these data are required in order to convert sound speed measurements on FeO-bearing liquids into compressibility data, which in turn are needed extend density models for magmatic liquids to elevated pressures. Moreover, there is growing evidence from the spectroscopic literature that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and thus it is possible that the partial molar volume and compressibility of FeO may vary with Fe2+ coordination, and thus with melt composition. To explore these issues, we have conducted both density and relaxed sound speed measurements on liquids in the CaO-FeO-SiO2 system, where the CaO/SiO2 ratio was systematically varied at constant FeO concentration (40 mol%). Density was measured between 1594 and 1813K with the double-bob Archimedean method using molybdenum bobs and crucible in a reducing gas (1%CO-99%Ar) environment. The sounds speeds were measured under similar conditions with a frequency-sweep acoustic interferometer. The derived partial molar volume of FeO increases systematically from 13.7 to 15.2 cm3/mol at 1673 K as the CaO/SiO2 ratio increases and the Fe2+ coordination number decreases. From a comparison with the crystalline volume of FeO (halite structure; 12.06 cm3/mol), which serves as a lower limit for VFeO in silicate liquids when Fe2+ is in 6-fold coordination, we estimate that the average Fe2+ coordination in our experimental melts extends up to values between 5 and 4, consistent with the spectroscopic literature. The partial molar compressibility of FeO also increases systematically as Fe2+ coordination decreases, and its maximum measured value (7.01 x 10-2 GPa-1) is nearly identical to that for the SiO2 component in 4-fold coordination (7.14 x 10-2 GPa-1) and is considerably larger than that for the relatively incompressible component MgO (0.65 x 10-2 GPa-1). Thus, our data indicate that the volumetric properties of FeO component have more in common with those for SiO2 than for MgO.

A notable difference between ideal gas and infinite molar volume limit of van der Waals gas

NASA Astrophysics Data System (ADS)

Liu, Q. H.; Shen, Y.; Bai, R. L.; Wang, X.

2010-05-01

The van der Waals equation of state does not sufficiently represent a gas unless a thermodynamic potential with two proper and independent variables is simultaneously determined. The limiting procedures under which the behaviour of the van der Waals gas approaches that of an ideal gas are letting two van der Waals coefficients be zero rather than letting the molar volume become infinitely large; otherwise, the partial derivative of internal energy with respect to pressure at a fixed temperature does not vanish.

Volumetric and calorimetric properties of aqueous ionene solutions

PubMed Central

Lukšič, Miha; Hribar-Lee, Barbara

2016-01-01

The volumetric (partial and apparent molar volumes) and calorimetric properties (apparent heat capacities) of aqueous cationic polyelectrolyte solutions – ionenes – were studied using the oscillating tube densitometer and differential scanning calorimeter. The polyion’s charge density and the counterion properties were considered as variables. The special attention was put to evaluate the contribution of electrostatic and hydrophobic effects to the properties studied. The contribution of the CH2 group of the polyion’s backbone to molar volumes and heat capacities was estimated. Synergistic effect between polyion and counterions was found. PMID:28503012

Partial molar enthalpies and reaction enthalpies from equilibrium molecular dynamics simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schnell, Sondre K.; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720; Department of Chemistry, Faculty of Natural Science and Technology, Norwegian University of Science and Technology, 4791 Trondheim

2014-10-14

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 obtainedmore » 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.« less

Calorimetric and computational study of indanones.

PubMed

Matos, M Agostinha R; Miranda, Margarida S; Monte, Manuel J S; Santos, Luís M N B F; Morais, Victor M F; Chickos, James S; Umnahanant, Patamaporn; Liebman, Joel F

2007-11-01

Condensed phase standard (p degrees = 0.1 MPa) molar enthalpies of formation for 1-indanone, 2-indanone, and 1,3-indandione were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of sublimation for 1-indanone and 2-indanone, at T = 298.15 K, were measured both by correlation-gas chromatography and by Calvet microcalorimetry leading to a mean value for each compound. For 1,3-indandione, the standard molar enthalpy of sublimation was derived from the vapor pressure dependence on temperature. The following enthalpies of formation in gas phase, at T = 298.15 K, were then derived: 1-indanone, -64.0 +/- 3.8 kJ mol(-1); 2-indanone, -56.6 +/- 4.8 kJ mol(-1); 1,3-indandione, -165.0 +/- 2.6 kJ mol(-1). The vaporization and fusion enthalpies of the indanones studied are also reported. In addition, theoretical calculations using the density functional theory with the B3LYP and MPW1B95 energy functionals and the 6-311G** and cc-pVTZ basis sets have been performed for these molecules and the corresponding one-ring species to obtain the most stable geometries and to access their energetic stabilities.

In Vivo Effect of Calcium Hydroxide and Resin-modified Glass Ionomer Cement on Carious Dentin in Young Permanent Molars: An Ultrastructural and Macroscopic Study.

PubMed

Opal, Shireen; Garg, Shalini; Sharma, Deepak; Dhindsa, Abhishek; Jatana, Isha

2017-01-15

The purpose of this study was to evaluate macroscopically and ultrastructurally the effect of calcium hydroxide cement (CH) and resin-modified glass ionomer cement (RMGIC) compared with gutta percha (control) as a lining material on carious dentin after partial caries removal and sealing. Twenty-seven permanent molars with deep carious lesions underwent partial caries removal with the application of CH, RMGIC, or gutta percha (control) and were then sealed for three months. After a partial caries removal and sealing period, the dentin was macroscopically assessed (for color, consistency, and humidity) and further analyzed by scanning electron microscope to assess the ultrastructural changes in dentin (lumen size, mineralization of tubules, occlusion of tubules by cements, and bacterial ingress). The effect of treatment in each group was statistically analyzed. Dentin darkening and hardening were observed after the sealing period in all groups. However, there was no difference in the color after treatment among the three groups. It was observed that RMGIC showed a significant reduction in the size of the lumen compared to CH and the control. Partial caries removal and sealing resulted in dentin hardening, darkening, and dentin remineralization, irrespective of the dentin protection used.

Free energies of formation of WC and WzC and the thermodynamic properties of carbon in solid tungsten

NASA Technical Reports Server (NTRS)

Gupta, D. K.; Seigle, L. L.

1974-01-01

The activity of carbon in the two-phase regions - W + WC and W + W2C was obtained from the carbon content of iron rods equilibrated with mixtures of metal plus carbide powders. From this activity data the standard free energies of formation of WC and W2C were calculated. The temperature of the invariant reaction W2C = W + WC was fixed at 1570 + or - 5K. Using available solubility data for C in solid W, the partial molar free energy of C in the dilute solid solution was also calculated. The heat of solution of C in W, and the excess entropy for the interstitial solid solution, were computed, assuming that the carbon atoms reside in the octahedral interstices of bcc W.

Differences between the chewing and non-chewing sides of the mandibular first molars and condyles in the closing phase during chewing in normal subjects.

PubMed

Tomonari, Hiroshi; Kwon, Sangho; Kuninori, Takaharu; Miyawaki, Shouichi

2017-09-01

This study aimed to assess differences between the closing paths of the chewing and non-chewing sides of mandibular first molars and condyles during natural mastication, using standardized model food in healthy subjects. Thirty-two healthy young adults (age: 19-25 years; 22 men, 10 women) with normal occlusion and function chewed on standardized gummy jelly. Using an optoelectric jaw-tracking system with six degrees of freedom, we recorded the path of the mandibular first molars and condyles on both sides for 10 strokes during unilateral chewing. Variables were compared between the chewing side and the non-chewing side of first molars and condyles on frontal, sagittal, and horizontal views during the early-, middle- and late-closing phases. On superior/inferior displacements, the chewing side first molar and condyle were positioned superior to those on the non-chewing side during the early- and middle-closing phases. Conversely, the first molar and condyle on the non-chewing side were positioned significantly superior to those on the chewing side during the late-closing phase. On anterior/posterior displacements, the chewing side mandibular first molar and condyle were positioned significantly posterior to those on the non-chewing side throughout all closing phases. Our results showed the differences between the mandibular first molars and condyles on both sides with respect to masticatory path during natural chewing of a model food. These differences can be useful for informing initial diagnostic tests for impaired masticatory function in the clinical environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of immediate post-extraction socket irrigation on development of alveolar osteitis after mandibular third molar removal: a prospective split-mouth study, preliminary report.

PubMed

Tolstunov, L

2012-12-01

The aim of this prospective comparative split-mouth study was to evaluate the role of socket irrigation with a normal saline solution routinely used at the end of extraction on the development of alveolar osteitis (AO) after removal of impacted mandibular third molars (MTMs). Thirty-five patients who satisfied the inclusion criteria were involved in the study and underwent extraction of four third-molars. To be included in the study, the mandibular third molars had to be impacted (partial or full bone) and require an osteotomy for extraction with use of a motorised drill. All surgeries were done under local anaesthesia or IV sedation. This was a prospective split-mouth study. The patient's left (assistant) side was a control side; it had a standard extraction technique of an impacted mandibular third molar that required a buccal full-thickness flap, buccal trough (osteotomy) and extraction of the tooth (with or without splitting the tooth into segments), followed by a traditional end-of-surgery debridement protocol consisting of a gentle curettage, bone filing of the socket walls, socket irrigation with approximately 5 ml of sterile normal saline solution and socket suctioning. The patient's right (operator) side was an experimental side; it also had a standard extraction technique of an impacted mandibular third molar at the beginning with a flap and osteotomy, but it was followed by a modified end-of-surgery protocol. It consisted of gentle curettage but the socket was not irrigated and not suctioned. It was simply left to bleed. The gauze was placed on top of the socket for haemostasis on both sides and the patient was asked to bite. On both sides, the buccal flap was positioned back without the suture. All patients were seen for a follow-up appointment four to seven days after the surgery to assess healing and check for symptoms and signs of alveolar osteitis, if present, on both irrigated and non-irrigated sides. This study followed the ethical guidelines of human subjects based on the Helsinki Declaration. Thirty-five patients or 70 sockets were evaluated. Eleven out of 35 patients in the study were subjected to a dry socket syndrome (31.4%). The higher number of AO was likely related to specifics of MTM selection in this study - only impacted (partial and full bone) MTMs were chosen. Among eleven patients with AO, two patients had a bilateral condition. By excluding two patients with bilateral dry sockets from the study, there were nine patients (18 extraction sites) with unilateral AO in the study. Seven out of nine patients (14 extraction sites) developed unilateral dry socket on the control (irrigated) side (77.8%) and only two (four extraction sites) on the experimental (non-irrigated) side (22.2%). Therefore, in this study there were 3.5 times more patients (extraction sites) with dry socket syndrome on the irrigated (control) side than patients (extraction sites) in the non-irrigated (experimental) side. A noticeable difference of dry socket syndromes (77.8% on the irrigated versus 22.2% on non-irrigated side) was demonstrated between the traditional extraction protocol versus modified approach without the end-of-surgery irrigation. The study demonstrated that the post-extraction socket bleeding is very important for the proper uncomplicated socket healing. If it's not washed away with irrigation solution at the end of extraction, the normal blood clot has a higher likelihood to form, and therefore, can potentially lead to an uncomplicated socket healing without development of alveolar osteitis. Socket bleeding at the extraction site creates a favourable environment for the formation of a blood clot - a protective dressing - necessary for a favourable osseous healing of the socket.

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

PubMed

Toedtling, V; Coulthard, P; Thackray, G

2016-09-23

Objectives The objectives of the prospective study were to establish the prevalence of distal caries (DC) in the mandibular second molar and to assess the outcomes of these diseased teeth in our population. Further aims were to identify associated risk factors and to design a protocol for prevention.Methods Clinical and radiographic data from 210 consecutive patients were ascertained over a three-month period. The sample population included all patients who had been referred to a hospital oral surgery department for a lower wisdom tooth assessment.Results A total of 224 mandibular third molars were included and assessed. The prevalence of caries affecting the distal aspect of the second molar was 38% (n = 85) in this population. In 18% of patients there was evidence of early enamel caries. Fifty-eight percent of caries was managed with restorative treatment but 11% of patients required second molar extraction and 13% of patients required the removal of the second and third molars. The prevalence of distal caries was significantly higher in patients with partially erupted wisdom teeth positioned below the amelocemental junction (P <0.05) of the adjacent second molar and in patients who presented with mesioangular impactions (P <0.001). However there was no difference in dental health when comparing this group to the remaining study population (P = 0.354). The Pearson chi-square test and Pearson correlation coefficient were used to verify the association between the tested variables.Conclusion This study demonstrates that the eruption status, type of angulation and the nature of tooth contact between both molars are useful disease predictors which can be used to indicate the likelihood of a caries process occurring on the distal aspect of the second mandibular molar. If patients' third molar teeth are not removed then consideration needs to be given to prevention and regular monitoring.

Theoretical and experimental study on the effects of particle size and temperature on the reaction kinetics of cubic nano-Cu2O

NASA Astrophysics Data System (ADS)

Tang, Huanfeng; Huang, Zaiyin; Xiao, Ming; Liang, Min; Chen, Liying; Tan, XueCai

2017-09-01

The activities, selectivities, and stabilities of nanoparticles in heterogeneous reactions are size-dependent. In order to investigate the influencing laws of particle size and temperature on kinetic parameters in heterogeneous reactions, cubic nano-Cu2O particles of four different sizes in the range of 40-120 nm have been controllably synthesized. In situ microcalorimetry has been used to attain thermodynamic data on the reaction of Cu2O with aqueous HNO3 and, combined with thermodynamic principles and kinetic transition-state theory, the relevant reaction kinetic parameters have been evaluated. The size dependences of the kinetic parameters are discussed in terms of the established kinetic model and the experimental results. It was found that the reaction rate constants increased with decreasing particle size. Accordingly, the apparent activation energy, pre-exponential factor, activation enthalpy, activation entropy, and activation Gibbs energy decreased with decreasing particle size. The reaction rate constants and activation Gibbs energies increased with increasing temperature. Moreover, the logarithms of the apparent activation energies, pre-exponential factors, and rate constants were found to be linearly related to the reciprocal of particle size, consistent with the kinetic models. The influence of particle size on these reaction kinetic parameters may be explained as follows: the apparent activation energy is affected by the partial molar enthalpy, the pre-exponential factor is affected by the partial molar entropy, and the reaction rate constant is affected by the partial molar Gibbs energy. [Figure not available: see fulltext.

In Vitro Comparison of Marginal and Internal Fit of Press-on-Metal Ceramic (PoM) Restorations with Zirconium-Supported and Conventional Metal Ceramic Fixed Partial Dentures Before and After Veneering.

PubMed

Varol, Seda; Kulak-Özkan, Yasemin

2015-07-01

To compare marginal and internal fit between 3- and 4-unit press-on-metal (PoM) ceramic, zirconia-supported, and conventional metal ceramic fixed partial dentures (FPDs) before and after veneering. Ten pieces for each 3- and 4-unit MC, IPS InLine PoM, and IPS e.max ZirCAD/Zir Press FPDs were produced. Cross-sections from silicone replicas were examined and measured with a light microscope. Occlusal, axial, intermarginal, and marginal mean adaptation scores of cross-sectioned replicas and means of measurements obtained from 4 sites were calculated independently. Mean values for molars were 78.44 ± 32.01 μm (MC), 89.84 ± 29.20 μm (PoM), and 85.17 ± 28.49 μm (Zir). Premolar values were 76.08 ± 27.92 μm (MC), 89.94 ± 23.49 μm (PoM), and 87.18 ± 28.25 μm (Zir). No difference existed between the means of 3- and 4-unit FPDs except the molar-intermarginal region. The mean value of 4-unit FPDs (93.88 ± 25.41 μm) was less than the 3-unit FPDs (103.68 ± 24.55 μm) at the molar-inter marginal region. A gap increase was observed in all sites except the molar-axio-occlusal region after veneering. According to the mean difference, gap increases at the molar-marginal, molar-intermarginal, and premolar-intermarginal regions were statistically significant. A statistical difference was found at the molar-marginal region for 4-unit MCR (p = 0.041) and 4-unit PoM FPDs (p = 0.042) before and after veneering. Gap increase after veneering of 4-unit metal ceramics at molar-intermarginal, premolar-marginal, and premolar-intermarginal regions (p = 0.020; p = 0.015; p = 0.004) was significant. The gap measurements of the IPS InLine PoM and IPS e.max ZirCAD/Zir Press groups were all clinically acceptable. No studies on marginal and internal fit in the IPS InLine PoM system have been published to date. This study should be supported with future studies. No significant increase was observed after press-veneering the IPS e.max ZirCAD frameworks with an IPS e.max ZirPress material; therefore, we recommend the use of this combination. © 2014 by the American College of Prosthodontists.

Experimental and computational investigation of the thermochemistry of the six isomers of dichloroaniline.

PubMed

Ribeiro da Silva, Manuel A V; Amaral, Luísa M P F; Gomes, José R B

2006-07-27

The standard (p(o) = 0.1 MPa) molar enthalpies of formation of 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-dichloroanilines were derived from the standard molar energies of combustion, in oxygen, to yield CO(2)(g), N(2)(g) and HCl.600H(2)O(l), at T = 298.15 K, measured by rotating bomb combustion calorimetry. The Calvet high-temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of the six isomers. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the six isomers of dichloroaniline, in the gaseous phase, at T = 298.15 K. The gas-phase enthalpies of formation were also estimated by G3MP2B3 calculations, which were further extended to the computation of gas-phase acidities, proton affinities, and ionization enthalpies.

Elucidation of ionic interactions in the protic ionic liquid solutions by isothermal titration calorimetry.

PubMed

Rai, Gitanjali; Kumar, Anil

2014-04-17

The strong hydrogen-bonded network noted in protic ionic liquids (PILs) may lead to stronger interactions of the ionic entities of PILs with solvents (water, methanol, ethylene glycol, dimethylsulfoxide (DMSO), N,N'-dimethylformamide (DMF)) as compared with those of aprotic ionic liquids (APILs). The PILs used in this work are 1-methylimidazolium tetrafluoroborate, 2-methylpyridinium tetrafluoroborate, and N-methylpyrrolodinium tetrafluoroborate in comparison to 1-butyl-3-methylimidazolium tetrafluoroborate, which is classified as an APIL. In this work, the excess partial molar enthalpy, H(E)IL obtained from isothermal calorimetric titrations at 298.15 K is used to probe the nature of interactions of the PIL cations with solvent molecules against those present in APIL-solvent systems. This work also reports interesting flip-flopping in the thermal behavior of these PIL-solvent systems depending upon the structure of the cationic ring of a PIL. In some cases, these flip-flops are the specific fingerprints for specific PILs in a common solvent environment. The excess partial molar enthalpy at infinite dilution, H(E,∞)IL, of these PILs bears a critical dependence on the solvent properties. An analysis of relative apparent molar enthalpies, ϕL, of the PIL solutions by the ion interaction model of Pitzer yields important information on ionic interactions of these systems.

Energetic studies and phase diagram of thioxanthene.

PubMed

Freitas, Vera L S; Monte, Manuel J S; Santos, Luís M N B F; Gomes, José R B; Ribeiro da Silva, Maria D M C

2009-11-19

The molecular stability of thioxanthene, a key species from which very important compounds with industrial relevance are derived, has been studied by a combination of several experimental techniques and computational approaches. The standard (p degrees = 0.1 MPa) molar enthalpy of formation of crystalline thioxanthene (117.4 +/- 4.1 kJ x mol(-1)) was determined from the experimental standard molar energy of combustion, in oxygen, measured by rotating-bomb combustion calorimetry at T = 298.15 K. The enthalpy of sublimation was determined by a direct method, using the vacuum drop microcalorimetric technique, and also by an indirect method, using a static apparatus, where the vapor pressures at different temperatures were measured. The latter technique was used for both crystalline and undercooled liquid samples, and the phase diagram of thioxanthene near the triple point was obtained (triple point coordinates T = 402.71 K and p = 144.7 Pa). From the two methods, a mean value for the standard (p degrees = 0.1 MPa) molar enthalpy of sublimation, at T = 298.15 K (101.3 +/- 0.8 kJ x mol(-1)), was derived. From the latter value and from the enthalpy of formation of the solid, the standard (p degrees = 0.1 MPa) enthalpy of formation of gaseous thioxanthene was calculated as 218.7 +/- 4.2 kJ x mol(-1). Standard ab initio molecular orbital calculations were performed using the G3(MP2)//B3LYP composite procedure and several homodesmotic reactions in order to derive the standard molar enthalpy of formation of thioxanthene. The ab initio results are in excellent agreement with the experimental data.

A combined experimental and computational thermodynamic study of difluoronitrobenzene isomers.

PubMed

Ribeiro da Silva, Manuel A V; Monte, Manuel J S; Lobo Ferreira, Ana I M C; Oliveira, Juliana A S A; Cimas, Álvaro

2010-10-14

This work reports the experimental and computational thermochemical study performed on three difluorinated nitrobenzene isomers: 2,4-difluoronitrobenzene (2,4-DFNB), 2,5-difluoronitrobenzene (2,5-DFNB), and 3,4-difluoronitrobenzene (3,4-DFNB). The standard (p° = 0.1 MPa) molar enthalpies of formation in the liquid phase of these compounds were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by rotating bomb combustion calorimetry. A static method was used to perform the vapor pressure study of the referred compounds allowing the construction of the phase diagrams and determination of the respective triple point coordinates, as well as the standard molar enthalpies of vaporization, sublimation, and fusion for two of the isomers (2,4-DFNB and 3,4-DFNB). For 2,5-difluoronitrobenzene, only liquid vapor pressures were measured enabling the determination of the standard molar enthalpies of vaporization. Combining the thermodynamic parameters of the compounds studied, the following standard (p° = 0.1 MPa) molar enthalpies of formation in the gaseous phase, at T = 298.15 K, were derived: Δ(f)H(m)° (2,4-DFNB, g) = -(296.3 ± 1.8) kJ · mol⁻¹, Δ(f)H(m)° (2,5-DFNB, g) = -(288.2 ± 2.1) kJ · mol⁻¹, and Δ(f)H(m)° (3,4-DFNB, g) = -(302.4 ± 2.1) kJ · mol⁻¹. Using the empirical scheme developed by Cox, several approaches were evaluated in order to identify the best method for estimating the standard molar gas phase enthalpies of formation of these compounds. The estimated values were compared to the ones obtained experimentally, and the approach providing the best comparison with experiment was used to estimate the thermodynamic behavior of the other difluorinated nitrobenzene isomers not included in this study. Additionally, the enthalpies of formation of these compounds along with the enthalpies of formation of the other isomers not studied experimentally, i.e., 2,3-DFNB, 2,6-DFNB, and 3,5-DFNB, were estimated using the composite G3MP2B3 approach together with adequate gas-phase working reactions. Furthermore, we also used this computational approach to calculate the gas-phase basicities, proton and electron affinities, and, finally, adiabatic ionization enthalpies.

Filling the gap: Calibration of the low molar-mass range of cellulose in size exclusion chromatography with cello-oligomers.

PubMed

Oberlerchner, J T; Vejdovszky, P; Zweckmair, T; Kindler, A; Koch, S; Rosenau, T; Potthast, A

2016-11-04

Degraded celluloses are becoming increasingly important as part of product streams coming from various biorefinery scenarios. Analysis of the molar mass distribution of such fractions is a challenge, since neither established methods for mono- or disaccharides nor common methods for polysaccharide characterization cover the intermediate oligomer range appropriately. Size exclusion chromatography (SEC) with multi-angle laser light scattering (MALLS), the standard approach for celluloses, suffers from decreased scattering intensities in the lower-molar mass range. The limitation in the low-molecular range can, in principle, be overcome by calibration, but calibration standards for such "short" celluloses are either not readily available or structurally remote and thus questionable. In this paper, we present the calibration of a SEC system- for the first time - with monodisperse cellooligomer standards up to about 3400gmol -1 . These cellooligomers are "short-chain celluloses" and can be seen as the "true" standard compounds, by contrast to commonly used standards that are chemically different from cellulose, such as pullulan, dextran, polystyrene, or poly(methyl methacrylate). The calibration is compared against those commercial standards and correction factors are calculated. Calibrations with non-cellulose standards can now be adjusted to yield better fitting results, and data already available can be corrected retrospectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Solution behavior of metoclopramide in aqueous-alcoholic solutions at 30°C

NASA Astrophysics Data System (ADS)

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

2016-07-01

Densities (ρ) and refractive indices ( n D) of solutions of antiemetic drug metoclopramide (4-amino-5-chloro- N-(2-(diethylamino)ethyl)-2-methoxybenzamide hydrochloride hydrate) in methanolwater and ethanol-water mixtures of different compositions were measured at 30°C. Apparent molar volume (φv) of the drug was calculated from density data and partial molar volumes (φ v 0 ) were determined from Massons relation. Concentration dependence of nD has been studied to determine refractive indices of solution at infinite dilution ( n D 0 ). Results have been interpreted in terms of solute-solvent interactions.

Experimental Techniques for Thermodynamic Measurements of Ceramics

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Putnam, Robert L.; Navrotsky, Alexandra

1999-01-01

Experimental techniques for thermodynamic measurements on ceramic materials are reviewed. For total molar quantities, calorimetry is used. Total enthalpies are determined with combustion calorimetry or solution calorimetry. Heat capacities and entropies are determined with drop calorimetry, differential thermal methods, and adiabatic calorimetry . Three major techniques for determining partial molar quantities are discussed. These are gas equilibration techniques, Knudsen cell methods, and electrochemical techniques. Throughout this report, issues unique to ceramics are emphasized. Ceramic materials encompass a wide range of stabilities and this must be considered. In general data at high temperatures is required and the need for inert container materials presents a particular challenge.

Intramaxillary and intermaxillary absolute anchorage with an endosseous dental implant and rare-earth magnets.

PubMed

Uribe, Flavio; Nanda, Ravindra

2009-07-01

This case report describes the management of a partially edentulous adult with a severe deepbite malocclusion and a collapsed buccal segment because of supraeruption of the maxillary second and third molars. The treatment involved placement of an endosseous dental implant to achieve absolute intermaxillary and intramaxillary anchorage. Rare-earth magnets embedded in acrylic bite-blocks were used to intrude the supraerupted maxillary molars on the right side. After use as an anchorage device, the implant was restored and brought into occlusion. Good occlusal and esthetic results were achieved with this cost-effective treatment.

Root canal morphology of South Asian Indian maxillary molar teeth

PubMed Central

Singh, Shishir; Pawar, Mansing

2015-01-01

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

Volumetric and acoustical behaviour of sodium saccharin in aqueous system over temperature range (20.0-45.0)°C.

PubMed

Jamal, Muhammad Asghar; Rashad, Muhammad; Khosa, Muhammad Kaleem; Bhatti, Haq Nawaz

2015-04-15

Densities and ultrasonic velocity values for aqueous solutions of sodium saccharin (SS) has been measured as a function of concentration at 20.0-45.0 °C and atmospheric pressure using DSA-5000 M. The density and ultrasonic velocity values have been further used to calculate apparent molar volume, apparent specific volume, isentropic apparent molar compressibility and compressibility hydration numbers and reported. The values for apparent molar volume obtained at given temperatures showed negative deviations from Debye-Hückel limiting law and used as a direct measure of the ion-ion and ion-solvent interactions. The apparent specific volumes of the solute were calculated and it was found that these values of the investigated solutions lie on the borderline between the values reported for sweet substances. The sweetness response of the sweeteners is then explained in terms of their solution behaviours. Furthermore, the partial molar expansibility, its second derivative, (∂(2)V°/∂T(2)) as Hepler's constant and thermal expansion coefficient have been estimated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Radiographic evaluation of bone regeneration after the application of plasma rich in growth factors in a lower third molar socket: a case report

PubMed Central

2009-01-01

A 42-year-old Mediterranean male presented complaining of inability to sustain good oral care at the posterior aspect of the lower right jaw. The main problems were food impaction in the area and the subsequent malodor. The patient reported remarkable medical history. Clinical examination revealed local erytherma with noticeable bone defect distal to the second molar with obvious defect in the mesial wall of the third molar; the penetration depth was found to be up to 6 mm. Radiological evaluation confirmed the defect and it was attributed to the mesioangularly partially impacted lower third molar. It was decided that third molar should be extracted and concentrate of the patient's growth factors (PRGF) to be applied into the bony defect to stimulate bone regeneration and promote healing. The third molar tooth was, then, removed surgically and the PRGF, which was prepared preoperatively, was implanted in the socket. At the first postoperative day, moderate pain was the main complaint and was controlled by NSAIDs. One week postoperatively, the sutures were removed and there was good tissue healing on examination. On the fiftieth postoperative day, radiographic evaluation took place and showed noticeable enhancement of density and radio-opacity in the third molar socket area, in comparison with the baseline image. Further, clinical examination showed significant reduction of periodontal pocketing and evidence of new bone formation. In conclusion, PRGF was very successful in stimulating bone regeneration and promote healing following dental extraction. PMID:20062651

Influence of hydrostatic pressure on dynamics and spatial distribution of protein partial molar volume: time-resolved surficial Kirkwood-Buff approach.

PubMed

Yu, Isseki; Tasaki, Tomohiro; Nakada, Kyoko; Nagaoka, Masataka

2010-09-30

The influence of hydrostatic pressure on the partial molar volume (PMV) of the protein apomyoglobin (AMb) was investigated by all-atom molecular dynamics (MD) simulations. Using the time-resolved Kirkwood-Buff (KB) approach, the dynamic behavior of the PMV was identified. The simulated time average value of the PMV and its reduction by 3000 bar pressurization correlated with experimental data. In addition, with the aid of the surficial KB integral method, we obtained the spatial distributions of the components of PMV to elucidate the detailed mechanism of the PMV reduction. New R-dependent PMV profiles identified the regions that increase or decrease the PMV under the high pressure condition. The results indicate that besides the hydration in the vicinity of the protein surface, the outer space of the first hydration layer also significantly influences the total PMV change. These results provide a direct and detailed picture of pressure induced PMV reduction.

Intrinsic alterations in the partial molar volume on the protein denaturation: surficial Kirkwood-Buff approach.

PubMed

Yu, Isseki; Takayanagi, Masayoshi; Nagaoka, Masataka

2009-03-19

The partial molar volume (PMV) of the protein chymotrypsin inhibitor 2 (CI2) was calculated by all-atom MD simulation. Denatured CI2 showed almost the same average PMV value as that of native CI2. This is consistent with the phenomenological question of the protein volume paradox. Furthermore, using the surficial Kirkwood-Buff approach, spatial distributions of PMV were analyzed as a function of the distance from the CI2 surface. The profiles of the new R-dependent PMV indicate that, in denatured CI2, the reduction in the solvent electrostatic interaction volume is canceled out mainly by an increment in thermal volume in the vicinity of its surface. In addition, the PMV of the denatured CI2 was found to increase in the region in which the number density of water atoms is minimum. These results provide a direct and detailed picture of the mechanism of the protein volume paradox suggested by Chalikian et al.

Raman Line Imaging of Poly(ε-caprolactone)/Carbon Dioxide Solutions at High Pressures: A Combined Experimental and Computational Study for Interpreting Intermolecular Interactions and Free-Volume Effects.

PubMed

Pastore Carbone, Maria Giovanna; Musto, Pellegrino; Pannico, Marianna; Braeuer, Andreas; Scherillo, Giuseppe; Mensitieri, Giuseppe; Di Maio, Ernesto

2016-09-01

In the present study, a Raman line-imaging setup was employed to monitor in situ the CO2 sorption at elevated pressures (from 0.62 to 7.10 MPa) in molten PCL. The method allowed the quantitative measurement of gas concentration in both the time-resolved and the space-resolved modes. The combined experimental and theoretical approach allowed a molecular level characterization of the system. The dissolved CO2 was found to occupy a volume essentially coincident with its van der Waals volume and the estimated partial molar volume of the probe did not change with pressure. Lewis acid-Lewis base interactions with the PCL carbonyls was confirmed to be the main interaction mechanism. The geometry of the supramolecular complex and the preferential interaction site were controlled more by steric than electronic effects. On the basis of the indications emerging from Raman spectroscopy, an equation of state thermodynamic model for the PCL-CO2 system, based upon a compressible lattice fluid theory endowed with specific interactions, has been tailored to account for the interaction types detected spectroscopically. The predictions of the thermodynamic model in terms of molar volume of solution have been compared with available volumetric measurements while predictions for CO2 partial molar volume have been compared with the values estimated on the basis of Raman spectroscopy.

Influence of posterior dental arch length on brain activity during chewing in patients with mandibular distal extension removable partial dentures.

PubMed

Shoi, K; Fueki, K; Usui, N; Taira, M; Wakabayashi, N

2014-07-01

It is well known that shortened dental arch decreases masticatory function. However, its potential to change brain activity during mastication is unknown. The present study investigates the effect of a shortened posterior dental arch with mandibular removable partial dentures (RPDs) on brain activity during gum chewing. Eleven subjects with missing mandibular molars (mean age, 66.1 years) on both sides received experimental RPDs with interchangeable artificial molars in a crossover trial design. Brain activity during gum chewing with RPDs containing (full dental arch) and lacking artificial molars (shortened dental arch) was measured using functional magnetic resonance imaging. Additionally, masticatory function was evaluated for each dental arch type. Food comminuting and mixing ability and the perceived chewing ability were significantly lower in subjects with a shortened dental arch than those with a full dental arch (P < 0.05). Brain activation during gum chewing with the full dental arch occurred in the middle frontal gyrus, primary sensorimotor cortex extending to the pre-central gyrus, supplementary motor area, putamen, insula and cerebellum. However, middle frontal gyrus activation was not observed during gum chewing with the shortened dental arch. These results suggest that shortened dental arch affects human brain activity in the middle frontal gyrus during gum chewing, and the decreased middle frontal gyrus activation may be associated with decreased masticatory function. © 2014 John Wiley & Sons Ltd.

Lattice potential energy and standard molar enthalpy in the formation of 1—dodecylamine hydrobromide (1-C12H25NH3·Br)(s)

NASA Astrophysics Data System (ADS)

Liu, Yu-Pu; Di, You-Ying; Dan, Wen-Yan; He, Dong-Hua; Kong, Yu-Xia; Yang, Wei-Wei

2011-02-01

This paper reports that 1-dodecylamine hydrobromide (1-C12H25NH3·Br)(s) has been synthesized using the liquid phase reaction method. The lattice potential energy of the compound 1-C12H25NH3·Br and the ionic volume and radius of the 1-C12H25NH3+ cation are obtained from the crystallographic data and other auxiliary thermodynamic data. The constant-volume energy of combustion of 1-C12H25NH3·Br(s) is measured to be ΔcUmo(1-C12H25NH3·Br, s) = -(7369.03±3.28) kJ·mol-1 by means of an RBC-II precision rotating-bomb combustion calorimeter at T = (298.15±0.001) K. The standard molar enthalpy of combustion of the compound is derived to be ΔcHmo(1-C12H25NH3·Br, s) = -(7384.52±3.28) kJ·mol-1 from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound is calculated to be ΔfHmo(1-C12H25NH3·Br, s)=-(1317.86±3.67) kJ·mol-1 from the standard molar enthalpy of combustion of the title compound and other auxiliary thermodynamic quantities through a thermochemical cycle.

The effect of box preparation on the strength of glass fiber-reinforced composite inlay-retained fixed partial dentures.

PubMed

Ozcan, Mutlu; Breuklander, Marijn H; Vallittu, Pekka K

2005-04-01

Nonstandardized box dimensions for inlay-retained fixed partial dentures (FPDs) may result in uneven distribution of the forces on the connector region of such restorations. The objective of this in vitro study was to evaluate the effect of box dimensions on the initial and final failure strength of inlay-retained fiber-reinforced composite (FRC) FPDs. Twenty-one inlay-retained FPDs were prepared using FRC (everStick) frameworks with unidirectional fiber reinforcement between mandibular first premolars and first molars. Boxes were prepared using conventional inlay burs (Cerinlay), and small and large ultrasonic tips (SONICSYS approx). Box dimensions were measured after preparation with a digital micrometer. All restorations were subjected to thermal cycling (6000 cycles, 5 degrees C-55 degrees C). Fracture testing was performed in a universal testing machine (1 mm/min). Acoustic emission signals were monitored during loading of the specimens. Initial and final fracture strength values (2-way ANOVA, Bonferroni post hoc tests, alpha =.05) and failure types (Fisher exact test) were statistically compared for each group. Significant differences (P =.0146 and P =.0086) were observed between the groups in the dimensions of the boxes prepared using conventional burs buccolingually (2.8-3.0 mm in molars, 3.1-4.3 mm in premolars) and the small size (2.5-2.9, 2.9-3.8 mm) or large size (2.6-3.8, 3.2-4.9 mm) ultrasonic tips for the premolars and the molars, respectively. No significant differences were found at the initial and final failures between the conventionally prepared group (842 +/- 267 N, 1161 +/- 428 N) and those prepared with either small (1088 +/- 381 N, 1320 +/- 380 N) or large ultrasonic tips (1070 +/- 280 N, 1557 +/- 321 N), respectively. The failure analysis demonstrated no significant difference in failure types but predominant delamination of the veneering resin (85%) in all experimental groups. According to acoustic emission tests, a higher energy level was required for final failure of the FRC FPDs with boxes finished using small ultrasonic tips. Standardized box dimensions showed no significant effect on fracture strength at either initial or final failure of the fiber-reinforced FPDs. The FRC FPDs with boxes refined with small ultrasonic burs required a greater energy level before failure. The type of failure observed after the fracture tests was primarily delamination of the veneering resin.

Synthesis of Mixed Cu/Ce Oxide Nanoparticles by the Oil-in-Water Microemulsion Reaction Method.

PubMed

Pemartin-Biernath, Kelly; Vela-González, Andrea V; Moreno-Trejo, Maira B; Leyva-Porras, César; Castañeda-Reyna, Iván E; Juárez-Ramírez, Isaías; Solans, Conxita; Sánchez-Domínguez, Margarita

2016-06-16

Cerium oxide and mixed Cu/Ce oxide nanoparticles were prepared by the oil-in-water (O/W) microemulsion reaction method in mild conditions. The Cu/Ce molar ratio was varied between 0/100 and 50/50. According to X-ray diffraction (XRD), below 30/70 Cu/Ce molar ratio, the materials presented a single phase consistent with cubic fluorite CeO₂. However, above Cu/Ce molar ratio 30/70, an excess monoclinic CuO phase in coexistence with the predominant Cu/Ce mixed oxide was detected by XRD and High-Resolution Transmission Electron Microscopy (HRTEM). Raman spectroscopy showed that oxygen vacancies increased significantly as the Cu content was increased. Band gap ( E g ) was investigated as a function of the Cu/Ce molar ratio, resulting in values from 2.91 eV for CeO₂ to 2.32 eV for the mixed oxide with 30/70 Cu/Ce molar ratio. These results indicate that below 30/70 Cu/Ce molar ratio, Cu 2+ is at least partially incorporated into the ceria lattice and very well dispersed in general. In addition, the photodegradation of Indigo Carmine dye under visible light irradiation was explored for selected samples; it was shown that these materials can remove such contaminants, either by adsorption and/or photodegradation. The results obtained will encourage investigation into the optical and photocatalytic properties of these mixed oxides, for widening their potential applications.

Synthesis of Mixed Cu/Ce Oxide Nanoparticles by the Oil-in-Water Microemulsion Reaction Method

PubMed Central

Pemartin-Biernath, Kelly; Vela-González, Andrea V.; Moreno-Trejo, Maira B.; Leyva-Porras, César; Castañeda-Reyna, Iván E.; Juárez-Ramírez, Isaías; Solans, Conxita; Sánchez-Domínguez, Margarita

2016-01-01

Cerium oxide and mixed Cu/Ce oxide nanoparticles were prepared by the oil-in-water (O/W) microemulsion reaction method in mild conditions. The Cu/Ce molar ratio was varied between 0/100 and 50/50. According to X-ray diffraction (XRD), below 30/70 Cu/Ce molar ratio, the materials presented a single phase consistent with cubic fluorite CeO2. However, above Cu/Ce molar ratio 30/70, an excess monoclinic CuO phase in coexistence with the predominant Cu/Ce mixed oxide was detected by XRD and High-Resolution Transmission Electron Microscopy (HRTEM). Raman spectroscopy showed that oxygen vacancies increased significantly as the Cu content was increased. Band gap (Eg) was investigated as a function of the Cu/Ce molar ratio, resulting in values from 2.91 eV for CeO2 to 2.32 eV for the mixed oxide with 30/70 Cu/Ce molar ratio. These results indicate that below 30/70 Cu/Ce molar ratio, Cu2+ is at least partially incorporated into the ceria lattice and very well dispersed in general. In addition, the photodegradation of Indigo Carmine dye under visible light irradiation was explored for selected samples; it was shown that these materials can remove such contaminants, either by adsorption and/or photodegradation. The results obtained will encourage investigation into the optical and photocatalytic properties of these mixed oxides, for widening their potential applications. PMID:28773602

[Application of hand-use ProTaper instruments in endodontic treatment of molar canals].

PubMed

Ma, Sui-qi; Xie, Qian; Zhou, Yin-feng

2010-07-01

To evaluate the application of hand-use ProTaper instruments in endodontic treatment of molar canals. A total of 203 permanent molars were randomly divided into the experimental group (99 molars) and control group (104 molars) prepared by hand-use ProTaper instruments and standard stainless steel K-file, respectively. The molars in the two groups were obturated by cold lateral condensation technique. The root canal preparation and obturation were evaluated by radiograph, and the working time of preparation and post-operative emergencies were analyzed. The preparation time in the experimental group was obviously shorter than that in the control group (P<0.01). The rate of satisfactory effect was significantly higher in the experimental group than in the control group (P<0.01), and the rate of post-operative emergencies was significantly lower in the experimental group (P<0.01). The application of hand-use ProTaper instruments may improve the effect of root canal treatment of the molars and shorten the working time and reduce the post-operative emergencies.

Radiographic evaluation of third molar development in 6- to 24-year-olds

PubMed Central

Jung, Yun-Hoa

2014-01-01

Purpose This study investigated the developmental stages of third molars in relation to chronological age and compared third molar development according to location and gender. Materials and Methods A retrospective analysis of panoramic radiographs of 2490 patients aged between 6 and 24 years was conducted, and the developmental stages of the third molars were evaluated using the modified Demirjian's classification. The mean age, standard deviation, minimal and maximal age, and percentile distributions were recorded for each stage of development. A Mann-Whitney U test was performed to test the developmental differences in the third molars between the maxillary and mandibular arches and between genders. A linear regression analysis was used for assessing the correlation between the third molar development and chronological age. Results The developmental stages of the third molars were more advanced in the maxillary arch than the mandibular arch. Males reached the developmental stages earlier than females. The average age of the initial mineralization of the third molars was 8.57 years, and the average age at apex closure was 21.96 years. The mean age of crown completion was 14.52 and 15.04 years for the maxillary and the mandibular third molars, respectively. Conclusion The developmental stages of the third molars clearly showed a strong correlation with age. The third molars developed earlier in the upper arch than the lower arch; further, they developed earlier in males than in females. PMID:25279338

Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study

PubMed Central

Mah, Su-Jung; Kim, Ji-Eun; Ahn, Eun Jin; Nam, Jong-Hyun; Kim, Ji-Young

2016-01-01

Skeletal anchorage-assisted upper molar distalization has become one of the standard treatment modalities for the correction of Class II malocclusion. The purpose of this study was to analyze maxillary molar movement patterns according to appliance design, with the simultaneous use of buccal fixed orthodontic appliances. The authors devised two distinct types of midpalatal miniscrew-assisted maxillary molar distalizers, a lingual arch type and a pendulum type. Fourteen patients treated with one of the two types of distalizers were enrolled in the study, and the patterns of tooth movement associated with each type were compared. Pre- and post-treatment lateral cephalograms were analyzed. The lingual arch type was associated with relatively bodily upper molar distalization, while the pendulum type was associated with distal tipping with intrusion of the upper molar. Clinicians should be aware of the expected tooth movement associated with each appliance design. Further well designed studies with larger sample sizes are required. PMID:26877983

Management of inflammatory complications in third molar surgery: a review of the literature.

PubMed

Osunde, O D; Adebola, R A; Omeje, U K

2011-09-01

Pain, swelling and trismus are common complications associated with third molar surgery. These complications have been reported to have an adverse effect on the quality of life of patients undergoing third molar surgery. To review the different modalities of minimizing inflammatory complications in third molar surgery. A medline literature search was performed to identify articles on management of inflammatory complications in third molar surgery. Standard textbooks of Oral and Maxillofacial Surgery were also consulted and some local scientific publications on the subject were reviewed. Methods ranges from surgical closure techniques, use of drains, physical therapy and pharmacological means. Studies reviewed have shown that no single modality effectively minimizes postoperative pain, swelling and trismus without undesirable effects. Inflammatory complications after third molar surgery still remains an important factor in quality of life of patients at the early postoperative periods. Oral surgeons should be aware of the different modalities of alleviation of these complications to make postoperative recovery more comfortable for patients.

Clinical study of Mineral Trioxide Aggregate in primary molars. Comparison between Grey and White MTA--a long term follow-up (84 months).

PubMed

Cardoso-Silva, Cristina; Barbería, Elena; Maroto, Myriam; García-Godoy, Franklin

2011-02-01

The aim of the present study was to conduct a clinical and radiographic long-term evaluation of pulpotomy in temporary molars performed with Grey and White Mineral Trioxide Aggregate (MTA) and compare the results of Grey and White MTA pulpotomies in a sample of 233 primary molars with a maximum follow-up period of 84 months. The sample was selected from patients treated at the Department of Pediatric Dentistry, Faculty of Dentistry, Complutense University of Madrid, Spain. This prospective study included first and second primary molars treated with pulpotomy with Grey or White MTA, controlled for a maximum follow-up period of 84 months. Statistical analysis of clinical and radiographic findings was completed using ANOVA (P<0.05). Follow-up evaluations, performed every 6 months, revealed that only 2 molars treated with White MTA presented abscess and pathological mobility. Radiographic examination of the 210 molars revealed unfavourable pulp response in only 6 molars (internal or furcation root resorption), without statistically significant differences between Grey and White MTA. Two radiological findings were noticed: dentine bridge formation and partial or total root canal stenosis. Grey MTA induced a higher percentage of dentine bridges with statistically significant differences (P<0.05), and a higher percentage of pulp canal stenosis, without a statistically significant difference. Grey and White MTA presented high levels of clinical and radiographic success. Although the present study showed evidence of a very good biologic response with both types of MTA, Grey MTA showed significantly higher number of dentine bridge formation than White MTA. Copyright © 2010 Elsevier Ltd. All rights reserved.

Impact of the lower third molar presence and position on the fragility of mandibular angle and condyle: A Three-dimensional finite element study.

PubMed

Antic, Svetlana; Vukicevic, Arso M; Milasinovic, Marko; Saveljic, Igor; Jovicic, Gordana; Filipovic, Nenad; Rakocevic, Zoran; Djuric, Marija

2015-07-01

The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3. In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Translational Diffusion Coefficient and Partition Coefficient of a Spin-Labeled Solute in Lecithin Bilayer Membranes

PubMed Central

Dix, James A.; Diamond, Jared M.; Kivelson, Daniel

1974-01-01

The translational diffusion coefficient and the partition coefficient of a spin-labeled solute, di-t-butyl nitroxide, in an aqueous suspension of dipalmitoyl lecithin vesicles have been studied by electron spin resonance spectroscopy. When the lecithin is cooled through its phase transition temperature near 41°C, some solute is “frozen out” of the bilayer, and the standard partial molar enthalpy and entropy of partition go more positive by a factor of 8 and 6, respectively. However, the apparent diffusion constant in the lecithin phase is only slightly smaller than that in water, both above and below the transition temperature. The fraction of bilayer volume within which solute is distributed may increase with temperature, contributing to the positive enthalpy of partition. Comparison of time constants suggests that there is a permeability barrier to this solute in the periphery of the bilayer. PMID:4360944

The Partial Molar Volume and Thermal Expansivity of Fe2O3 in Alkali Silicate Liquids: Evidence for the Average Coordination of Fe3+

NASA Astrophysics Data System (ADS)

Liu, Q.; Lange, R.

2003-12-01

Ferric iron is an important component in magmatic liquids, especially in those formed at subduction zones. Although it has long been known that Fe3+ occurs in four-, five- and six-fold coordination in crystalline compounds, only recently have all three Fe3+ coordination sites been confirmed in silicate glasses utilizing XANES spectroscopy at the Fe K-edge (Farges et al., 2003). Because the density of a magmatic liquid is largely determined by the geometrical packing of its network-forming cations (e.g., Si4+, Al3+, Ti4+, and Fe3+), the capacity of Fe3+ to undergo composition-induced coordination change affects the partial molar volume of the Fe2O3 component, which must be known to calculate how the ferric-ferrous ratio in magmatic liquids changes with pressure. Previous work has shown that the partial molar volume of Fe2O3 (VFe2O3) varies between calcic vs. sodic silicate melts (Mo et al., 1982; Dingwell and Brearley, 1988; Dingwell et al., 1988). The purpose of this study is to extend the data set in order to search for systematic variations in VFe2O3 with melt composition. High temperature (867-1534° C) density measurements were performed on eleven liquids in the Na2O-Fe2O3-FeO-SiO2 (NFS) system and five liquids in the K2O-Fe2O3-FeO-SiO2 (KFS) system using Pt double-bob Archimedean method. The ferric-ferrous ratio in the sodic and potassic liquids at each temperature of density measurement were calculated from the experimentally calibrated models of Lange and Carmichael (1989) and Tangeman et al. (2001) respectively. Compositions range (in mol%) from 4-18 Fe2O3, 0-3 FeO, 12-39 Na2O, 25-37 K2O, and 43-78 SiO2. Our density data are consistent with those of Dingwell et al. (1988) on similar sodic liquids. Our results indicate that for all five KFS liquids and for eight of eleven NFS liquids, the partial molar volume of the Fe2O3 component is a constant (41.57 ñ 0.14 cm3/mol) and exhibits zero thermal expansivity (similar to that for the SiO2 component). This value was obtained in a fit to a linear volume equation in which the other oxide components have the following fitted partial molar volumes (cm3/mol) at 1100° C: SiO2 = 26.85+/-0.04, Na2O = 26.57+/-0.07, K2O = 42.34+/-0.10, and FeO = 12.84+/-0.28, and the following fitted fitted partial molar thermal expansivities (10-3 cm3/mol-K): Na2O = 7.73+/-0.12, K2O = 11.99+/-0.24, and FeO = 2.88+/-1.22. For the three sodic liquids not included in this regression, the most iron-rich (18.2 mol% Fe2O3) has a value for VFe2O3 of 44.1 cm3/mole, whereas the most iron-poor (4.4 mol% Fe2O3) has a value for VFe2O3 of 37.0 cm3/mole. This trend may reflect a greater proportion of four-fold ferric iron in iron-rich liquids, which mirrors the trend of increasing ferric-ferrous ratios in sodic liquids as a function of total iron content (Lange and Carmichael, 1989). The most polymerized liquid in our data set was a sodic liquid that has a value for VFe2O3 of 45.0 cm3/mole. It thus appears that most (13 of 16) of our experimental liquids, which span a wide compositional range, lead to a VFe2O3 (41.6 cm3/mol) which is constant with composition and temperature. However, there are three important outliers that may have implications for the appropriate value to apply to magmatic liquids.

Molecular energetics of cytosine revisited: a joint computational and experimental study.

PubMed

Gomes, José R B; Ribeiro da Silva, Maria D M C; Freitas, Vera L S; Ribeiro da Silva, Manuel A V

2007-08-02

A static bomb calorimeter has been used to measure the standard molar energy of combustion, in oxygen, at T = 298.15 K, of a commercial sample of cytosine. From this energy, the standard (p degrees = 0.1 MPa) molar enthalpy of formation in the crystalline state was derived as -(221.9 +/- 1.7) kJ.mol(-1). This value confirms one experimental value already published in the literature but differs from another literature value by 13.5 kJ.mol(-1). Using the present standard molar enthalpy of formation in the condensed phase and the enthalpy of sublimation due to Burkinshaw and Mortimer [J. Chem. Soc., Dalton Trans. 1984, 75], (155.0 +/- 3.0) kJ.mol(-1), results in a value for the gas-phase standard molar enthalpy of formation for cytosine of -66.9 kJ.mol(-1). A similar value, -65.1 kJ.mol(-1), has been estimated after G3MP2B3 calculations combined with the reaction of atomization on three different tautomers of cytosine. In agreement with experimental evidence, the hydroxy-amino tautomer is the most stable form of cytosine in the gas phase. The enthalpies of formation of the other two tautomers were also estimated as -60.7 kJ.mol(-1) and -57.2 kJ.mol(-1) for the oxo-amino and oxo-imino tautomers, respectively. The same composite approach was also used to compute other thermochemical data, which is difficult to be measured experimentally, such as C-H, N-H, and O-H bond dissociation enthalpies, gas-phase acidities, and ionization enthalpies.

Volume of reaction by the Archibald ultracentrifuge method (lobster hemocyanin).

PubMed

Saxena, V P; Kegeles, G; Kikas, R

1976-07-01

Samples of lobster hemocyanin (Homarus americanus) under conditions of reversible reaction between whole (25 S) and half (17 S) molecules have been subjected to accurately known nitrogen pressures in analytical ultracentrifuge cells. A modified pressurization chamber of the type developed by Schumaker and colleagues has been constructed for this purpose. The molecular weight was then determined at the top (liquid-gas) meniscus, by means of the Archibald method. The logarithmic dependence upon pressure of the derived equilibrium constant then gave directly the volume of reaction. Experiments were performed in veronal-citrate buffers at pH 8, where the molar volume of formation of whole (dodecameric) molecules from half molecules appears to be negative, and at pH 8.46 in veronal-citrate buffer in the presence of 0.003 molar free calcium ion, where the molar volume of formation was estimated to be + 390 cm3/mole. In glycine-sodium hydroxide buffer at pH 9.6 containing 0.0047 molar free calcium, the molar volume of formation of whole molecules was estimated to be +120 +/- 70 cm3, corresponding to an estimated difference in partial specific volume between whole molecules and half molecules of only 1.3 (10)-4cm3/gram. The correctness of the sign of this value in glycine buffer has been verified by pressure-jump light-scattering experiments.

Radiographic correlation of dental and skeletal age: Third molar, an age indicator.

PubMed

Suma, Gn; Rao, Balaji B; Annigeri, Rajeshwari G; Rao, Dayashankara Jk; Goel, Sumit

2011-01-01

Age estimation plays a great role in forensic investigations, orthodontic and surgical treatment planning, and tooth transplantation. Teeth offer an excellent material for age determination by stages of development below the age of 25 years and by secondary changes after the age of 25 years. Third molar is often not included for this purpose due to its notorious developmental patterns. The aim of this study was to evaluate the development of third molar anlage in relation to skeletal maturities and the chronological age. One hundred and fifty-six young individuals, 78 males and 78 females, were selected. The stages of development of all the third molars in every individual were determined from panoramic radiographs. The skeletal development was assessed using hand wrist radiographs. Data were analyzed statistically for mean value, standard deviation and the relationship between the recorded characteristics. A STRONG CORRELATION WAS FOUND BETWEEN THIRD MOLAR DEVELOPMENT AND SKELETAL MATURITY (IN MALES: r=0.88, P<0.001; in females: r=0.77 for maxillary third molar and 0.89 for mandibular third molar, P<0.001). Hence, it is concluded that a strong correlation exists between chronological age, developmental stages of third molars and maturation of epiphyses of hand. Any of the three parameters could be used for the assessment of other maturities.

[Effects of shortened mandibular dental arch on human brain activity during chewing: an fMRI study].

PubMed

Shoi, Kazuhito

2014-03-01

According to the shortened dental arch concept, missing molars should not always be restored with prosthetic treatment. A shortened dental arch with missing molars is associated with a decrease in masticatory function. However, it is not known whether a shortened dental arch influences brain activity during chewing. This study aimed to clarify the effect of posterior arch length of mandibular bilateral distal extension removable partial dentures (RPDs) on brain activity during chewing. Eleven subjects with bilaterally missing mandibular molars (mean age, 66.1 years) participated in the study. RPDs with full dental arch and shortened dental arch were fabricated and brain activity during gum chewing under each dental condition was measured using functional magnetic resonance imaging. Brain activation during gum chewing with the full dental arch was observed in the middle frontal gyrus, primary sensorimotor cortex extending to the premotor cortex, supplementary motor area, putamen, insula and cerebellum. However, activation of the middle frontal gyrus was not observed during gum chewing with the shortened dental arch. The results of this study suggest that human brain activity during chewing in the middle frontal gyrus may be associated with chewing in the presence of the molar region.

Effectiveness of a personalized device in the evaluation of mandibular second molar periodontal healing after surgical extraction of adjacent third molar.

PubMed

Pippi, Roberto

2013-01-01

The primary aim of the present study was to validate the effectiveness of a personalized device able to guide periodontal probing in evaluation of second molar periodontal healing after adjacent third molar surgical extraction. Secondarily, the study analyzed if any patient and tooth related factors affected the second molar periodontal healing as well as if they were able to affect the periodontal probing depth performed with or without the personalized device. Thirty-five lower second molars were evaluated after extraction of the adjacent third molar. Pre-operative as well as 3 and 12 month post-operative probing depths of the distal surface of the second molar were evaluated. All measurements were taken by two different methods: standard two-point and four-point probing using a personalized onlay-type guide. Periapical radiographs were also evaluated. The Pearson product moment and the general linear model with backward stepwise procedure were used for inferential statistics. The mean 12-month post-operative probing depth/mean pre-operative probing depth ratio obtained with the guided probing method showed a highly significant effect on the 12-month radiographic post-operative/pre-operative radiographic measure ratio. None of the examined patient- or tooth-related factors showed a significant effect on pre-operative/12-month post-operative radiographic measure ratio. The use of the proposed personalized device seems to provide a more reliable estimate of second molar periodontal healing after adjacent third molar surgical extraction. No patient-or tooth-related factors seem to be able to affect either second molar periodontal healing or probing depth measures obtained with or without the personalized device in individuals younger than 25 years old. It can be therefore recommended that lower third molar surgical extraction be performed in young adults.

Thermodynamics of the interaction of the food additive tartrazine with serum albumins: a microcalorimetric investigation.

PubMed

Basu, Anirban; Kumar, Gopinatha Suresh

2015-05-15

The thermodynamics of the interaction of the food colourant tartrazine with two homologous serum proteins, HSA and BSA, were investigated, employing microcalorimetric techniques. At T=298.15K the equilibrium constants for the tartrazine-BSA and HSA complexation process were evaluated to be (1.92 ± 0.05) × 10(5)M(-1) and (1.04 ± 0.05) × 10(5)M(-1), respectively. The binding was driven by a large negative standard molar enthalpic contribution. The binding was dominated essentially by non-polyelectrolytic forces which remained largely invariant at all salt concentrations. The polyelectrolytic contribution was weak at all salt concentrations and accounted for only 6-18% of the total standard molar Gibbs energy change in the salt concentration range 10-50mM. The negative standard molar heat capacity values, in conjunction with the enthalpy-entropy compensation phenomenon observed, established the involvement of dominant hydrophobic forces in the complexation process. Tartrazine enhanced the stability of both serum albumins against thermal denaturation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Strains Around Abutment Teeth with Different Attachments Used for Implant-Assisted Distal Extension Partial Overdentures: An In Vitro Study.

PubMed

ELsyad, Moustafa Abdou; Omran, Abdelbaset Omar; Fouad, Mohammed Mohammed

2017-01-01

The aim of this study was to evaluate and compare strain around abutment teeth with different attachments used for implant-assisted distal extension partial overdentures (IADEPODs). A mandibular Kennedy class I acrylic model (remaining teeth from first premolar to first premolar) was constructed. A conventional partial denture was constructed over the model (control, group 1). Two laboratory implants were then placed bilaterally in the first molar areas parallel to each other and perpendicular to the residual ridge. Three additional experimental partial overdentures (PODs) were constructed and connected to the implants using ball (group 2), magnetic (group 3), and Locator (group 4) attachments. Three linear strain gauges were bonded buccal, lingual, and distal to the first premolar abutment tooth at the right (loading) and the left (nonloading) sides. For each group, a universal testing device was used to apply a unilateral vertical static load (50 N) on the first molar area, and the strain was recorded using a multichannel digital strainometer. Significant differences between groups and between sites of strain gauges were detected. Strains recorded for all groups were compressive (negative) in nature. Group 1 demonstrated the highest strain, followed by group 3 and group 4; group 2 recorded the lowest strain. For group 2, the highest strain was recoded at the lingual nonloading side. For group 1, group 3, and group 4, the highest strain was recorded at the buccal loading side. Within the limitation of the present study, ball attachments used to retain IADEPODs to the implants were associated with lower strains around abutment teeth than Locator and magnetic attachments. The highest strain was recorded with conventional partial dentures. © 2015 by the American College of Prosthodontists.

Anatomical analysis of the resected roots of mandibular first molars after failed non-surgical retreatment

PubMed Central

2018-01-01

Objectives Understanding the reason for an unsuccessful non-surgical endodontic treatment outcome, as well as the complex anatomy of the root canal system, is very important. This study examined the cross-sectional root canal structure of mandibular first molars confirmed to have failed non-surgical root canal treatment using digital images obtained during intentional replantation surgery, as well as the causative factors of the failed conventional endodontic treatments. Materials and Methods This study evaluated 115 mandibular first molars. Digital photographic images of the resected surface were taken at the apical 3 mm level and examined. The discolored dentin area around the root canal was investigated by measuring the total surface area, the treated areas as determined by the endodontic filling material, and the discolored dentin area. Results Forty 2-rooted teeth showed discolored root dentin in both the mesial and distal roots. Compared to the original filled area, significant expansion of root dentin discoloration was observed. Moreover, the mesial roots were significantly more discolored than the distal roots. Of the 115 molars, 92 had 2 roots. Among the mesial roots of the 2-rooted teeth, 95.7% of the roots had 2 canals and 79.4% had partial/complete isthmuses and/or accessory canals. Conclusions Dentin discoloration that was not visible on periapical radiographs and cone-beam computed tomography was frequently found in mandibular first molars that failed endodontic treatment. The complex anatomy of the mesial roots of the mandibular first molars is another reason for the failure of conventional endodontic treatment. PMID:29765897

Computing gas solubility in reservoir waters for environmental chemistry applications: the role of satellite observations

NASA Astrophysics Data System (ADS)

Rosa, R.; Lima, I.; Ramos, F.; Bambace, L.; Assireu, A.; Stech, J.; Novo, E.; Lorenzeti, L.

Atmospheric greenhouse gases concentration has increased during the past centuries basically due to biogenic and pyrogenic anthopogenic emissions Recent investigations have shown that gas emission methane as an important example from tropical hydroelectric reservoirs may comprise a considerable fraction of the total anthropogenic bulk In order to evaluate the concentration of gases of potential importance in environmental chemistry the solubility of such gases have been collected and converted into a uniform format using the Henry s law which states that the solubility of a gas in a liquid is directly proportional to its partial pressure However the Henry s law can be derived as a function of temperature density molar mixing ratio in the aqueous phase and molar mass of water In this paper we show that due to the complex temperature variation and water composition measured in brazilian tropical reservoirs as Serra da Mesa and Manso expressive secular variation on the traditional solubility constants concentration of a species in the aqueous phase by the partial pressure of that species in the gas phase can change in a rate of approximately 30 in 6 decades This estimation comes from a computational analysis of temperature variation measured during 6 months in Serra da Mesa and Manso reservoirs taking into account a simulated density and molar mass variation of the aqueous composition in these environments As an important global change issue from this preliminary analysis we discuss its role in the current estimations on the concentration emission rates

The Density and Compressibility of BaCO3-SrCO3-CaCO3-K2CO3-Na2CO3-Li2CO3 Liquids: New Measurements and a Systematic Trend with Cation Field Strength

NASA Astrophysics Data System (ADS)

Hurt, S. M.; Lange, R. A.; Ai, Y.

2015-12-01

The volumetric properties of multi-component carbonate liquids are required to extend thermodynamic models that describe partial melting of the deep mantle (e.g. pMELTS; Ghiorso et al., 2003) to carbonate-bearing lithologies. Carbonate in the mantle is an important reservoir of carbon, which is released to the atmosphere as CO2 through volcanism, and thus contributes to the carbon cycle. Although MgCO3 is the most important carbonate component in the mantle, it is not possible to directly measure the 1-bar density and compressibility of MgCO3 liquid because, like other alkaline-earth carbonates, it decomposes at a temperature lower than its melting temperature. Despite this challenge, Liu and Lange (2003) and O'Leary et al. (2015) showed that the one bar molar volume, thermal expansion and compressibility of the CaCO3 liquid component could be obtained by measuring the density and sound speeds of stable liquids in the CaCO3-Li2CO3-Na2CO3-K2CO3 quaternary system at one bar. In this study, this same strategy is employed on SrCO3- and BaCO3-bearing alkali carbonate liquids. The density and sound speed of seven liquids in the SrCO3-Li2CO3-Na2CO3-K2CO3 quaternary and three liquids in the BaCO3-Li2CO3-Na2CO3-K2CO3 quaternary were measured from 739-1367K, with SrCO3 and BaCO3 concentrations ranging from 10-50 mol%. The density measurements were made using the double-bob Archimedean method and sound speeds were obtained with a frequency-sweep acoustic interferometer. The molar volume and sound speed measurements were used to calculate the isothermal compressibility of each liquid, and the results show the volumetric properties mix ideally with composition. The partial molar volume and compressibility of the SrCO3 and BaCO3 components are compared to those obtained for the CaCO3 component as a function of cation field strength. The results reveal a systematic trend that allows the partial molar volume and compressibility of the MgCO3 liquid component to be estimated.

HIGH TEMPERATURE SULFATION STUDIES IN AN ISOTHERMAL REACTOR: A COMPARISON OF THEORY AND EXPERIMENT

EPA Science Inventory

The paper gives high-temperature isothermal data on sulfur dioxide (SO2) capture, obtained as a function of temperature, SO2 partial pressure, and Ca/S molar ratio for a pulverized dolomite (34 micrometer mean size) and a high-purity calcite (11 micrometer mean size). The experim...

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Third molars and premolars extraction in conventional orthodontics and in treatments based on maxillary bone remodeling with temporary anchorage: indications and care.

PubMed

Consolaro, Alberto

2017-02-01

A bone is an anatomic structure in constant remodeling, with different, mutant and wonderfully inconstant designs. With every new and immediate functional demand, there are changes in cortical thickness, trabecular bone density and also in direction and size of trabeculae. Bones' non-stopping search is for adjusting to the functions induced by forces and movements required by a certain life style. Conventional orthodontic planning or with temporary anchorage based on bone remodeling takes into consideration the spaces that are - or may be - occupied by the teeth, in the formation of a functional and esthetic dental arch for the patient. In case it is necessary to extract a tooth and the options are the third molars, partially or totally unerupted, and teeth that belong to other dental groups, obviousness recommends - due to mouth anatomy and physiology, as well as pathologic reasons - extracting the third molars, due to of the several reasons described in the present study.

Third molars and premolars extraction in conventional orthodontics and in treatments based on maxillary bone remodeling with temporary anchorage: indications and care

PubMed Central

Consolaro, Alberto

2017-01-01

ABSTRACT A bone is an anatomic structure in constant remodeling, with different, mutant and wonderfully inconstant designs. With every new and immediate functional demand, there are changes in cortical thickness, trabecular bone density and also in direction and size of trabeculae. Bones' non-stopping search is for adjusting to the functions induced by forces and movements required by a certain life style. Conventional orthodontic planning or with temporary anchorage based on bone remodeling takes into consideration the spaces that are - or may be - occupied by the teeth, in the formation of a functional and esthetic dental arch for the patient. In case it is necessary to extract a tooth and the options are the third molars, partially or totally unerupted, and teeth that belong to other dental groups, obviousness recommends - due to mouth anatomy and physiology, as well as pathologic reasons - extracting the third molars, due to of the several reasons described in the present study. PMID:28444013

Synthesis of 1,3-Dimethylimidazolium Chloride and Volumetric Property Investigations of Its Aqueous Solution

NASA Astrophysics Data System (ADS)

Dong, L.; Zheng, D. X.; Wei, Z.; Wu, X. H.

2009-10-01

By investigating the vapor pressure of the solvent and the affinity between ionic liquids (ILs) and the solvent, it is proposed that 1,3-dimethylimidazolium chloride ([Mmim]Cl) has the potential to be used as a novel absorbent species with the absorption cycle working fluid. Adopting a high-pressure reaction kettle, the method of gas-liquid phase reaction was used to synthesize [Mmim]Cl under the conditions of 348.15 K and 0.7 MPa. The densities of [Mmim]Cl aqueous solutions were measured for mass fractions in the range from 20% to 90% at 293.15 K, 298.15 K, 303.15 K, 308.15 K, 313.15 K, and 318.15 K with a digital vibrating-tube densimeter. The excess volume, the apparent molar volume, the partial molar volume, and the apparent molar expansibility of this system were investigated, and the influences of variations of the cation and anion on the density of several IL aqueous solutions are discussed.

[Determination of solubility parameters of high density polyethylene by inverse gas chromatography].

PubMed

Wang, Qiang; Chen, Yali; Liu, Ruiting; Shi, Yuge; Zhang, Zhengfang; Tang, Jun

2011-11-01

Inverse gas chromatographic (IGC) technology was used to determine the solubility parameters of high density polyethylene (HDPE) at the absolute temperatures from 303.15 to 343.15 K. Six solvents were applied as test probes including hexane (n-C6), heptane (n-C7), octane (n-C8), nonane (n-C9), chloroform (CHCl3) and ethyl acetate (EtAc). Some thermodynamic parameters were obtained by IGC data analysis such as the specific retention volumes of the solvents (V(0)(g)), the molar enthalpy of sorption (delta H(S)(1)), the partial molar enthalpy of mixing at infinite dilution (delta H(1)(infinity)), the molar enthalpy of vaporization (delta H(v)), the activity coefficients at infinite dilution (omega (1)(infinity)), and Flow-Huggins interaction parameters (X(1,2)(infinity)) between HDPE and probe solvents. The results showed that the above six probes are poor solvents for HDPE. The solubility parameter of HDPE at room temperature (298.15 K) was also derived as 19.00 (J/cm3)(0.5).

Studying pressure denaturation of a protein by molecular dynamics simulations.

PubMed

Sarupria, Sapna; Ghosh, Tuhin; García, Angel E; Garde, Shekhar

2010-05-15

Many globular proteins unfold when subjected to several kilobars of hydrostatic pressure. This "unfolding-up-on-squeezing" is counter-intuitive in that one expects mechanical compression of proteins with increasing pressure. Molecular simulations have the potential to provide fundamental understanding of pressure effects on proteins. However, the slow kinetics of unfolding, especially at high pressures, eliminates the possibility of its direct observation by molecular dynamics (MD) simulations. Motivated by experimental results-that pressure denatured states are water-swollen, and theoretical results-that water transfer into hydrophobic contacts becomes favorable with increasing pressure, we employ a water insertion method to generate unfolded states of the protein Staphylococcal Nuclease (Snase). Structural characteristics of these unfolded states-their water-swollen nature, retention of secondary structure, and overall compactness-mimic those observed in experiments. Using conformations of folded and unfolded states, we calculate their partial molar volumes in MD simulations and estimate the pressure-dependent free energy of unfolding. The volume of unfolding of Snase is negative (approximately -60 mL/mol at 1 bar) and is relatively insensitive to pressure, leading to its unfolding in the pressure range of 1500-2000 bars. Interestingly, once the protein is sufficiently water swollen, the partial molar volume of the protein appears to be insensitive to further conformational expansion or unfolding. Specifically, water-swollen structures with relatively low radii of gyration have partial molar volume that are similar to that of significantly more unfolded states. We find that the compressibility change on unfolding is negligible, consistent with experiments. We also analyze hydration shell fluctuations to comment on the hydration contributions to protein compressibility. Our study demonstrates the utility of molecular simulations in estimating volumetric properties and pressure stability of proteins, and can be potentially extended for applications to protein complexes and assemblies. Proteins 2010. (c) 2009 Wiley-Liss, Inc.

Association between mandibular third molar formation and retromolar space.

PubMed

Ghougassian, Saro S; Ghafari, Joseph G

2014-11-01

To assess the association between formation stages of the mandibular third molars and the space distal to the permanent molars (retromolar space). The material included pretreatment lateral cephalographs of 96 orthodontic patients (49 males, 47 females; 8-18 years old). The molar formation stage was assessed through the method of Nolla, which rates the degree of calcification on a scale of 10 stages. The retromolar space was measured from the most concave point of the anterior border of the ramus to the distal surface of the first molar (used because the second molars had not yet erupted in the younger patients). Statistical analyses included t-tests and analyses of variance for group differences and the Pearson product moment to gauge associations among variables. The formation stage advanced with age, but wide standard deviations were noted. Similarly, the retromolar distance increased with age and was greatest between 10 and 12 years. The correlation between retromolar space and developmental stage was high (r  =  0.85). On average, an increase of 5 mm of retromolar space corresponds to a 1.8 stage in tooth maturation. The correlation between third molar mineralization and available retromolar space essentially represents the association between one biologic age (dental formation) and another growth-related event (mandibular skeletal growth). The findings do not necessarily reflect successful emergence or nonimpaction of the molars. Longitudinal data are needed to determine such outcomes.

Third molar development by measurements of open apices in an Italian sample of living subjects.

PubMed

De Luca, Stefano; Pacifici, Andrea; Pacifici, Luciano; Polimeni, Antonella; Fischetto, Sara Giulia; Velandia Palacio, Luz Andrea; Vanin, Stefano; Cameriere, Roberto

2016-02-01

The aim of this study is to analyse the age-predicting performance of third molar index (I3M) in dental age estimation. A multiple regression analysis was developed with chronological age as the independent variable. In order to investigate the relationship between the I3M and chronological age, the standard deviation and relative error were examined. Digitalized orthopantomographs (OPTs) of 975 Italian healthy subjects (531 female and 444 male), aged between 9 and 22 years, were studied. Third molar development was determined according to Cameriere et al. (2008). Analysis of covariance (ANCOVA) was applied to study the interaction between I3M and the gender. The difference between age and third molar index (I3M) was tested with Pearson's correlation coefficient. The I3M, the age and the gender of the subjects were used as predictive variable for age estimation. The small F-value for the gender (F = 0.042, p = 0.837) reveals that this factor does not affect the growth of the third molar. Adjusted R(2) (AdjR(2)) was used as parameter to define the best fitting function. All the regression models (linear, exponential, and polynomial) showed a similar AdjR(2). The polynomial (2nd order) fitting explains about the 78% of the total variance and do not add any relevant clinical information to the age estimation process from the third molar. The standard deviation and relative error increase with the age. The I3M has its minimum in the younger group of studied individuals and its maximum in the oldest ones, indicating that its precision and reliability decrease with the age. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Retrospective chart analysis on survival rate of fixtures installed at the tuberosity bone for cases with missing unilateral upper molars: a study of 7 cases.

PubMed

Park, Young-Jin; Cho, Sung-Am

2010-06-01

To evaluate the survival rate of implants placed in the maxillary tuberosity region using the fixed prosthesis in partially edentulous cases. Of implant-treated patients who visited Kyung Pook National University Hospital, 7 partially edentulous patients (2 male and 5 female; mean age, 52.3 years; range, approximately 43 to 65) were selected according to the following criteria: 1) less than 3-mm thickness alveolar bone reaming at the first molar area and 2) 1 to 2 fixture premolars, with the additional implant at the maxillary tuberosity region. For the control group, patients who had nontuberosity areas were selected. After 1 to 7 years, marginal bone level, fixture mobility, and radiolucency of tuberosity fixtures of the fixed prostheses were evaluated by digital panorama (Starpacs, Infinitt, Seoul, Korea). None of the fixtures of the tuberosity-installed implants for 1 to 7 years failed. The marginal bone level around the implants of the maxillary tuberosity 1 to 6 years (average 3.4 years) after the final prostheses was approximately 0.6 to 1.3 mm, with an average of 0.94 mm. The fixture installation at the maxillary tuberosity using the unilateral partially edentulous implant-fixed prosthesis would be a clinically acceptable treatment module. 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Three-year clinical follow-up of posterior teeth restored with leucite-reinforced ips empress onlays and partial veneer crowns.

PubMed

Murgueitio, Rafael; Bernal, Guillermo

2012-07-01

The aim of this study was to analyze the survival rate and failure mode of IPS leucite-reinforced ceramic onlays and partial veneer crowns regarding thickness under the following clinical conditions: vital versus nonvital teeth, tooth location, and type of opposing dentition. Teeth were prepared according to established guidelines for ceramic onlays and partial veneer crowns. Before cementation, the restorations were measured for occlusal thickness at the central fossa, mesial, and distal marginal ridges, and functional and nonfunctional cusps. A total of 210 ceramic restorations were cemented in 99 patients within a mean observation period of 2.9 ± 1.89 years. The mode of failure was classified and evaluated as (1) adhesive, (2) cohesive, (3) combined failure, (4) decementation, (5) tooth sensitivity, and (6) pulpal necrosis. Kaplan, log-rank, and Cox regression tests were used for statistical analysis. The failure rate was 3.33% (7/210). Increased material thickness produced less probability of failures. Vital teeth were less likely to fail than nonvital teeth. Second molars were five times more susceptible to failure than first molars. Tooth sensitivity postcementation and the type of opposing dentition were not statistically significant in this study. In this study, thickness of the restorations, tooth vitality, and location of teeth in the dental arch influenced restoration failures. © 2012 by the American College of Prosthodontists.

Glass ionomer ART sealant and fluoride-releasing resin sealant in fissure caries prevention – results from a randomized clinical trial

PubMed Central

2014-01-01

Background The relative performance of ART sealant and fluoride-releasing resin sealant in preventing fissure caries in permanent molars was compared in a randomized clinical trial conducted in southern China (ClinicalTrials.gov NCT01829334). Methods After obtaining ethical approval, healthy schoolchildren who had permanent first molars with occlusal fissures which were sound but deep or presented with only incipient caries were recruited for the study. Included molars were randomly allocated into one of four parallel study groups in units of left/right teeth per mouth. Two of the four groups adopted the methods of ART or fluoride-releasing resin sealant placement while the other two groups adopted the topical fluoride application methods. Fissure status of the molars in each group was evaluated every 6 months. Development of dentine caries and sealant retention over 24 months in the molars in the two sealant-using groups was compared in this report. Outcome on cost-effectiveness of all four groups over 36 months will be reported elsewhere. Results At baseline, a total of 280 children (383 molars) with mean age 7.8 years were involved for the two sealant groups. After 24 months, 261 children (357 molars) were followed. Proportions of molars with dentine caries were 7.3% and 3.9% in the ART sealant and fluoride-releasing resin sealant groups, respectively (chi-square test, p = 0.171). Life-table survival analysis showed that sealant retention (full and partial) rate over 24 months for the resin sealant (73%) was significantly higher than that (50%) for the ART sealant (p < 0.001). Molar survival (no development of dentine caries) rates in the ART sealant (93%) and fluoride-releasing resin sealant (96%) groups were not significantly different (p = 0.169). Multilevel logistic regression (GEE modeling) accounting for the effects of data clustering and confounding factors confirmed this finding. Conclusions Though the retention of fluoride-releasing resin sealant was better than that of the ART sealant, their effectiveness in preventing fissure caries in permanent molars did not differ significantly over 24 months. ART sealants could be a good alternative when and where resources for resin sealant placement are not readily available. PMID:24886444

Molar distalization with pendulum appliances in the mixed dentition: effects on the position of unerupted canines and premolars.

PubMed

Kinzinger, Gero S M; Wehrbein, Heinrich; Gross, Ulrich; Diedrich, Peter R

2006-03-01

The pendulum appliance allows for rapid molar distalization without the need for patient compliance. Its efficiency has been confirmed in a number of clinical studies. However, the potential interactions and positional changes between the deciduous molars used for dental anchorage and the erupted and unerupted permanent teeth have yet to be clarified when this appliance is used for molar distalization in the mixed dentition. Twenty-nine patients in the mixed dentition each received a modified pendulum appliance with a distal screw and a preactivated pendulum spring for bilateral distalization of the maxillary molars. The patients were divided into 4 groups based on dentition stages: patient group 1 (PG 1, n = 10) was in the early mixed dentition; patients had resorption of the distal root areas of the deciduous molars being used for dental anchorage, and the unerupted premolars were located at the distal margin of the deciduous molar root region. Based on radiographs taken before placement of the pendulum appliance, patient group 2 (PG 2, n = 10) was diagnosed as having a central location of the unerupted premolars. In the third group (PG 3, n = 4), the first premolars were already erupted and could be integrated into the dental anchorage, but the canines were not yet erupted. In the fourth group (PG 4, n = 5), the first premolars and both canines were fully erupted. Statistical analysis of the measured results showed significant differences in the side effects between PG 1 and PG 2. In patients being treated with pendulum appliances, the anchorage quality of the deciduous molars that were already partially resorbed in the distal root area was comparatively reduced. Consequently, the mesial drift of the deciduous molars and incisors was increased, without impairing the extent and quality of the molar distalization. Anchorage loss in the supporting area had no direct impact on the sagittal position of the unerupted premolars in the early mixed dentition. If permanent teeth have already started to erupt in the supporting area, additional space restrictions should be avoided in patients with critical topography, especially if there is little space for the unerupted canines. At this stage of the mixed dentition, premolar extraction or augmentation of the supporting area with extraoral headgear offers a therapeutic alternative to intraoral distalization appliances with exclusively dental anchorage.

Effect of Amount of Carbon on the Reduction Efficiency of Iron Ore-Coal Composite Pellets in Multi-layer Bed Rotary Hearth Furnace (RHF)

NASA Astrophysics Data System (ADS)

Mishra, Srinibash; Roy, Gour Gopal

2016-08-01

The effect of carbon-to-hematite molar ratio has been studied on the reduction efficiency of iron ore-coal composite pellet reduced at 1523 K (1250 °C) for 20 minutes in a laboratory scale multi-layer bed rotary hearth furnace (RHF). Reduced pellets have been characterized through weight loss measurement, estimation of porosity, shrinkage, qualitative and quantitative phase analysis by XRD. Performance parameters such as the degree of reduction, metallization, carbon efficiency, productivity, and compressive strength have been calculated to compare the process efficacy at different carbon levels in the pellets. Pellets with optimum carbon-to-hematite ratio (C/Fe2O3 molar ratio = 1.66) that is much below the stoichiometric carbon required for direct reduction of hematite yielded maximum reduction, better carbon utilization, and productivity for all three layers. Top layer exhibited maximum reduction at comparatively lower carbon level (C/Fe2O3 molar ratio <2.33) in the pellet, while bottom layer exceeded top layer reduction at higher carbon level (C/Fe2O3 molar ratio >2.33). Correlation between degree of reduction and metallization indicated non-isothermal kinetics influenced by heat and mass transfer in multi-layer bed RHF. Compressive strength of the partially reduced pellet with optimum carbon content (C/Fe2O3 molar ratio = 1.66) showed that they could be potentially used as an alternate feed in a blast furnace or any other smelting reactor.

The retrotransposon Tf1 assembles virus-like particles that contain excess Gag relative to integrase because of a regulated degradation process.

PubMed

Atwood, A; Lin, J H; Levin, H L

1996-01-01

The retrotransposon Tf1, isolated from Schizosaccharomyces pombe, contains a single open reading frame with sequences encoding Gag, protease, reverse transcriptase, and integrase (IN). Tf1 has previously been shown to possess significant transposition activity. Although Tf1 proteins do assemble into virus-like particles, the assembly does not require readthrough of a translational reading frame shift or stop codon, common mechanisms used by retroelements to express Gag in molar excess of the polymerase proteins. This study was designed to determine if Tf1 particles contain equal amounts of Gag and polymerase proteins or whether they contain the typical molar excess of Gag. After using two separate methods to calibrate the strength of our antibodies, we found that both S. pombe extracts and partially purified Tf1 particles contained a 26-fold molar excess of Gag relative to IN. Knowing that Gag and IN are derived from the same Tf1 primary translation product, we concluded that the excess Gag most likely resulted from specific degradation of IN. We obtained evidence of regulated IN degradation in comparisons of Tf1 protein extracted from log-phase cells and that extracted from stationary-phase cells. The log-phase cells contained equal molar amounts of Gag and IN, whereas cells approaching stationary phase rapidly degraded IN, leaving an excess of Gag. Analysis of the reverse transcripts indicated that the bulk of reverse transcription occurred within the particles that possess a molar excess of Gag.

Clinical performance of a glass ionomer sealant protected with two different resin-based agents over a 2-year follow-up period.

PubMed

Ulusoy, A T; Tunc, E S; Bayrak, Ş

2017-03-01

To evaluate the effects of two different resin coating materials on the clinical performance of a conventional glass ionomer sealant. Permanent first mandibular molars of 60 children aged 6-9 years were sealed with Fuji VII. In each child, G-Coat Plus coating agent was applied to molars on one side and Heliobond coating agent to molars on the opposite side of the mouth. Clinical evaluations were carried out at 1, 6, 12, 18 and 24 months after sealant and coating application. At 1, 6, 12, 18 and 24 months after sealant and coating application, total sealant retention rates were 88%, 40%, 19%, 15% and 9% for molars coated with G-Coat Plus, and 93%, 47%, 17%, 15% and 7% for those coated with Heliobond. The differences between the two coating agents were not statistically significant (p>0.05). No incidence of caries was observed in either group during the two-year evaluation period. Wilcoxon signed rank test was used to compare differences in retention rates and caries incidence by coating agent. Although retention rates of Fuji VII were relatively low and similar for both resin coating agents tested, dental caries were not observed in either group during the 24-month study period. In children with a high risk of caries and partially erupted molars, the use of a glass ionomer sealant with a resin-based coating agent should be encouraged.

[Evaluation of cermet fillings in abutment teeth in removable partial prostheses].

PubMed

Saulic, S; Tihacek-Sojic, Lj

2001-01-01

The aim of the study was to describe the clinical process of setting the purpose filling on abutment teeth, after finishing the removable partial dentures. The aim was also to investigate the use of cermet glass-ionomer cement for the purpose filling in the abutment teeth for removable partial dentures, as well as to investigate the surface of the purpose filling. For the clinical evaluation of purpose filling slightly modified criteria according to Ryg's were used in 20 patients with different type of edentulousness. Changes occurring on the surface of purpose filling have been experimentally established by the method of scanning electron microscopy on the half-grown third molars in seven patients. It could be concluded that cement glass-ionomer was not the appropriate material for the purpose fillings in abutment teeth for removable partial dentures.

40 CFR 1066.630 - PDP, SSV, and CFV flow rate calculations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... per revolution, as determined in paragraph (a)(2) of this section. T std = standard temperature = 293.... p std = standard pressure= 101.325 kPa. (2) Calculate V rev using the following equation: ER28AP14... std = standard temperature. p std = standard pressure. Z = compressibility factor. M mix = molar mass...

The chronology of third molar eruption in the Croatian population.

PubMed

Brkić, Hrvoje; Vodanović, Marin; Dumancić, Jelena; Lovrić, Zeljka; Cuković-Bagić, Ivana; Petrovecki, Mladen

2011-06-01

Dental age estimation is common in orthodontics, paedodontics, paleodontology and forensic dentistry. The aim of this study was to assess chronological course of eruptive developmental phases of third molar and to establish parameters for the Croatian population. Sample of this study consisted of 1249 orthopantomograms of 530 (42.4%) male and 719 (57.6%) female subjects, aged 10 to 25 years. Eruptive phases were classified in 4 stages. No significant sex difference was found. Established chronology of the third molar eruption can be used as a standard for the assessment of dental age in clinical and forensic research on samples of Croatian population.

In-depth morphological study of mesiobuccal root canal systems in maxillary first molars: review

PubMed Central

Chang, Seok-Woo; Lee, Jong-Ki; Lee, Yoon

2013-01-01

A common failure in endodontic treatment of the permanent maxillary first molars is likely to be caused by an inability to locate, clean, and obturate the second mesiobuccal (MB) canals. Because of the importance of knowledge on these additional canals, there have been numerous studies which investigated the maxillary first molar MB root canal morphology using in vivo and laboratory methods. In this article, the protocols, advantages and disadvantages of various methodologies for in-depth study of maxillary first molar MB root canal morphology were discussed. Furthermore, newly identified configuration types for the establishment of new classification system were suggested based on two image reformatting techniques of micro-computed tomography, which can be useful as a further 'Gold Standard' method for in-depth morphological study of complex root canal systems. PMID:23493453

40 CFR 1066.605 - Mass-based and molar-based exhaust emission calculations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the test interval, corrected to standard temperature and pressure. m PMfil = mass of particulate... = stabilized, ht = hot transient), corrected to standard reference conditions. m PMfil = mass of particulate... stabilized), corrected to standard reference conditions. m PMfil = mass of particulate matter emissions on...

Effectiveness of a personalized device in the evaluation of mandibular second molar periodontal healing after surgical extraction of adjacent third molar

PubMed Central

Pippi, Roberto

2013-01-01

Summary Aim The primary aim of the present study was to validate the effectiveness of a personalized device able to guide periodontal probing in evaluation of second molar periodontal healing after adjacent third molar surgical extraction. Secondarily, the study analyzed if any patient and tooth related factors affected the second molar periodontal healing as well as if they were able to affect the periodontal probing depth performed with or without the personalized device. Materials and methods Thirty-five lower second molars were evaluated after extraction of the adjacent third molar. Pre-operative as well as 3 and 12 month post-operative probing depths of the distal surface of the second molar were evaluated. All measurements were taken by two different methods: standard two-point and four-point probing using a personalized onlay-type guide. Periapical radiographs were also evaluated. The Pearson product moment and the general linear model with backward stepwise procedure were used for inferential statistics. Results The mean 12-month post-operative probing depth/mean pre-operative probing depth ratio obtained with the guided probing method showed a highly significant effect on the 12-month radiographic post-operative/pre-operative radiographic measure ratio. None of the examined patient- or tooth-related factors showed a significant effect on pre-operative/12-month post-operative radiographic measure ratio. Conclusions The use of the proposed personalized device seems to provide a more reliable estimate of second molar periodontal healing after adjacent third molar surgical extraction. No patient-or tooth-related factors seem to be able to affect either second molar periodontal healing or probing depth measures obtained with or without the personalized device in individuals younger than 25 years old. It can be therefore recommended that lower third molar surgical extraction be performed in young adults. PMID:24611086

Physicochemical properties and ion-solvent interactions in aqueous sodium, ammonium, and lead acetate solution

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Mendkudle, M. S.

2014-09-01

Densities (ρ), viscosities (η) and refractive indices ( n D) of aqueous sodium acetate (SA), ammonium acetate (AA), and lead acetate (LA) solutions have been measured for different concentrations of salts at 302.15 K. Apparent molar volumes (φv) for studied solutions were calculated from density data, and fitted to Masson's relation and partial molar volume (φ{v/o}) was determined. Viscosity data were fitted to Jones-Dole equation and viscosity A- and B-coefficients were determined. Refractive index and density data were fitted to Lorentz and Lorenz equation and specific refraction ( R D) were calculated. Behavior of various physicochemical properties indicated presence of strong ion-solvent interactions in present systems and the acetate salts structure maker in water.

Commentary on the sphalerite geobarometer

USGS Publications Warehouse

Toulmin, P.; Barton, P.B.; Wiggins, L.B.

1991-01-01

The FeS content of sphalerite in assemblages with pyrite and pyrrhotite has been widely used and widely criticized as a geobarometer. The commonly accepted form of the geobarometer is based on the composition of sphalerite being independent of temperature below about 550??C at all pressures up to at least 10 kbar, but strong thermodynamic arguments require a significant temperature dependence in this region. Most minor components have a negligible effect on the relevant equilibria, but the effect of CuS is somewhat more significant. Molar and partial molar volumes for binary (ZnS-FeS) and ternary (ZnS-FeS-CuS) sphalerite solutions are presented; the ternary data are consistent with charge transfer between Cu and Fe. -from Authors

Ectopic eruption of first permanent molars: presenting features and associations.

PubMed

Mooney, G C; Morgan, A G; Rodd, H D; North, S

2007-09-01

To investigate presenting features of ectopically erupting first permanent molars and associations with other dental anomalies. Prospective convenience study. 28 panoral radiographs were collected, over a 24-month period, of 7-11 year-old children with radiographic evidence of ectopic eruption of first permanent molars who presented to a Dental Teaching Hospital in the North of England. A further 20 radiographs were collected of matched patients with no evidence of ectopic molar eruption. All radiographs were analysed under standard conditions to record the distribution and type of ectopic eruption (if present). In addition, the presence of the following dental anomalies was noted: cleft lip and/or palate; supernumerary teeth; hypodontia, and infraocclusion of primary molars. Chi-squared analysis was performed to determine any significant differences in the frequency of these dental anomalies between ectopic molar and control groups. For patients with ectopic molar eruption, the majority demonstrated ectopic eruption of either one or two first permanent molars (32% and 57% of subjects respectively). There were a similar proportion of 'jumps' and 'holds'. 92% of these were maxillary teeth and there was equal left and right distribution. Interestingly, a positive record of ectopic eruption was only documented in the dental records of 35.7% of these subjects. Children with ectopic eruption were significantly more likely to have at least one additional dental anomaly than was the case for the control group (60.7% versus 25%). Notably, primary molar infraocclusion and cleft lip/palate were significantly more frequent in the ectopic group. This study, the first in a British population, has identified a significant association between ectopic eruption of first permanent molars and other dental anomalies. A multifactorial aetiology is thus supported and clinicians should be alert to the co-existence of ectopic eruption and other dental anomalies.

Incisor and molar overjet, arch contraction, and molar relationship in the mixed dentition in repaired complete unilateral cleft lip and palate: A qualitative and quantitative appraisal.

PubMed

Disthaporn, Suteeta; Suri, Sunjay; Ross, Bruce; Tompson, Bryan; Baena, Diogenes; Fisher, David; Lou, Wendy

2017-07-01

To compare the mixed dentition incisor and molar overjet, severity of contraction of the dental arch, and the sagittal molar relationship on the cleft side vs the noncleft side in children with repaired complete unilateral cleft of the lip and palate (UCLP). Orthodontic records taken prior to orthodontic preparation for alveolar bone grafting were screened to select study casts from patients with nonsyndromic repaired complete UCLP who did not have mandibular skeletal or dental asymmetry. The study sample comprised dental casts from 74 children aged 8.9 ± 1 years. Standardized digital photographs were acquired at 1:1 magnification. A coordinate system was developed using digital image-processing software (Photoshop CS4 and Adobe Illustrator). Incisor and molar overjet, Angle's classification, and arch contraction were recorded. Descriptive statistics, paired t-tests, and kappa statistics were used to compare the cleft and noncleft sides. A negative overjet of -1 to -5 mm was often present at the incisors, with greater frequency and magnitude on the cleft side. Class II molar relation was more frequent on the cleft side (61.1%) than on the noncleft side (47.2%). Significantly greater contraction of the cleft side deciduous canine and deciduous first molar was noted, while the difference was very minor at the first permanent molar. Cleft side maxillary arch contraction was most severe in the deciduous canine and first deciduous molar region and progressively less severe in the posterior region of the arch. A greater frequency and severity of negative overjet and Class II molar relationship was seen on the cleft side.

Assessment of the potential of Allium sativum oil as a new medicament for non-vital pulpotomy of primary teeth.

PubMed

Mohammad, Shukry Gamal; Baroudi, Kusai

2015-01-01

The objective of this study was to compare the clinical and radiographic effects of Allium sativum oil and formocresol in nonvital pulpotomy in primary teeth. Twenty children ranging in age from 4 to 8 years were included in the study. In every one of those children, pulpotomy was indicated for the primary molars. Pulpotomy procedure was performed and the radicular pulp tissue of one molar was capped with A. sativum oil in a cotton pellet while the other molar was capped with formocresol. The teeth were evaluated clinically and radiographically before and after 6 months using standard clinical and radiographic criteria. Statistically, these results revealed significant difference between the radiographic findings of nonvital pulpotomy in primary molars with the two medicaments. Statistical analysis was performed using independent t-test and paired t-test at the significance level of α = 0.05. A. sativum oil has potent antibacterial properties that enable it to combat intracanal microbes in the infected pulp of primary molars. Better results were obtained when A. sativum oil was used. A. sativum oil had more powerful effects than formocresol on the infected pulp of primary nonvital molars.

A systematic review of dental disease management in cancer patients.

PubMed

Hong, Catherine H L; Hu, Shijia; Haverman, Thijs; Stokman, Monique; Napeñas, Joel J; Braber, Jacolien Bos-den; Gerber, Erich; Geuke, Margot; Vardas, Emmanouil; Waltimo, Tuomas; Jensen, Siri Beier; Saunders, Deborah P

2018-01-01

This systematic review aims to update on the prevalence of odontogenic-related infections and the efficacy of dental strategies in preventing dental-related complications in cancer patients since the 2010 systematic review. A literature search was conducted in the databases MEDLINE/PubMed and EMBASE for articles published between 1 January 2009 and 30 June 2016. Each study was assessed by 2 reviewers and the body of evidence for each intervention was assigned an evidence level. After examination of the abstracts and full-text articles, 59 articles satisfied the inclusion criteria. The weighted prevalence of dental infections and pericoronitis during cancer therapy was 5.4 and 5.3%, respectively. The frequency of dental-related infections during intensive chemotherapy after complete, partial, and minimal pre-cancer dental evaluation/treatment protocols ranged from 0 to 4%. Protocols involving third molars extractions had the highest complications (40%). In view of the low prevalence of infections and the potential for complications after third molar extractions, it is suggested that partial dental evaluation/treatment protocols prior to intensive chemotherapy; whereby minor caries (within dentin), asymptomatic third molars or asymptomatic teeth without excessive probing depth (<8 mm), mobility (mobility I or II) or with periapical lesions of <5 mm were observed; is a viable option when there is insufficient time for complete dental evaluation/treatment protocols. The use of chlorhexidine, fluoride mouth rinses as well as composite resin, resin-modified glass ionomer cement (GIC), and amalgam restorations over conventional GIC in post head and neck radiation patients who are compliant fluoride users is recommended.

Correlation between the frequency of eruption disorders for first permanent molars and the occurrence of malocclusions in early mixed dentition.

PubMed

Salbach, Anja; Schremmer, Britt; Grabowski, Rosemarie; Stahl de Castrillon, Franka

2012-08-01

We analyzed the incidence of eruption disorders in 6-year molars during the first phase of mixed dentition, and then determined the risks for later dental arch development according to specific combinations of orthodontic malocclusions. We, thus, aimed to derive potential conclusions for preventative orthodontics. In this cross-sectional study, 8,041 kindergarten and school children with early mixed dentition were randomly selected and clinically examined. Examinations were performed in two consecutive years during the standard dental screening that school children undergo. The average age was 6.9 years. We defined an eruption of the 6-year molars as being disturbed when (1) the distal cusps had erupted further than the mesial cusps, (2) the mesial inclination of the occlusal surface revealed disturbed eruption, and (3) the 6-year molar had erupted below the second primary molar. Disturbed eruption of the first permanent molars was observed in 102 of these children. The upper 6-year molars were affected more often (88.5%) than the lower molars. Bilateral disturbed eruption of the upper molars was the most frequent combination of symptoms found. Although disturbed eruption was diagnosed most often in 6- and 7-year-old children, the 8-year-old children presented 20% of the eruption disorders. Moreover, 72.6% of the children with disturbed eruption presented at least one additional orthodontic malocclusion. Crowding (p ≤ 0.001), lateral malocclusions (p ≤ 0.001), and mandibular prognathism (p = 0.009) were present significantly more often in children with disturbed eruption of 6-year molars. Delayed eruption and false direction of eruption of the upper 6-year molars may-already at an early stage-raise the likelihood of problems during later dental arch development, such as crowding in the sagittal and transverse directions or Class III developments.

Effect of Temperature on the Physico-Chemical Properties of a Room Temperature Ionic Liquid (1-Methyl-3-pentylimidazolium Hexafluorophosphate) with Polyethylene Glycol Oligomer

PubMed Central

Wu, Tzi-Yi; Chen, Bor-Kuan; Hao, Lin; Peng, Yu-Chun; Sun, I-Wen

2011-01-01

A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol) (PEG) [Mw = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ρ, refractive index, n, viscosity, η, and surface tension, γ, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values. PMID:21731460

Impaction of lower third molars and their association with age: radiological perspectives.

PubMed

Ryalat, Soukaina; AlRyalat, Saif Aldeen; Kassob, Zaid; Hassona, Yazan; Al-Shayyab, Mohammad H; Sawair, Faleh

2018-04-04

Third molars are the most commonly impacted teeth, and their extraction is the most commonly performed procedure in oral and maxillofacial surgery. The aim of the present study is to describe the pattern of mandibular third molar impaction and to define the most appropriate age for prophylactic extraction of mandibular third molar teeth. A total of 1198 orthopantomographs (OPGs) with 1810 impacted lower third molars were reviewed by two authors. The pattern of eruption in relation to patient's age was examined using standard radiographic points and angles. Statistical analysis was performed using SPSS for Windows release 16.0 (SPSS Inc., Chicago, IL, USA). In patients older than 20 years, vertical pattern of impaction was the most common (21.4%); while in young patients; horizontal impaction was more common (21.3%). Furthermore, there was a constant pattern of increase in Pell-Gregory ramus class 1 with increasing age, as the prevalence of class 1 was 0% at age 18 years compared to 54.9% at the age of 26 years. Frequency of vertical impaction of lower third molars was seen more at an older age (> 20 years) in this study, with an increase in the retromolar space. Late extraction of mandibular third molar teeth (i.e. after the age of 20) is therefore recommended when prophylactic extraction is considered.

Regenerative endodontic treatment (revascularization) of immature necrotic molars medicated with calcium hydroxide: a case series.

PubMed

Cehreli, Zafer C; Isbitiren, Beste; Sara, Sezgi; Erbas, Gizem

2011-09-01

Revascularization is an emerging regenerative treatment protocol with little published data available in immature molar teeth. The present case series demonstrates the outcome of revascularization treatment with intracanal medicament of calcium hydroxide in immature necrotic molars. Immature necrotic permanent first molars (n = 6) of patients 8-11 years old were treated by a revascularization protocol that used 2.5% NaOCl irrigation, medication with calcium hydroxide placed in the coronal third of the root canals, induction of apical bleeding, and coronal sealing with white mineral trioxide aggregate. Among the treated teeth, 4 molars had undergone prior root canal instrumentation by the referring dentists. National Institutes of Health Image-J program with TurboReg plug-in was used for standardization of the radiographs and to determine the increase in root length and root width. After a follow-up period of 10 months, all teeth demonstrated radiographic evidence of complete periapical healing, progressive thickening of dentinal walls, and continued apical development in the absence of clinical symptoms. Two uninstrumented molars showed a positive response to cold testing at 9 months. On the basis of a follow-up period of 10 months, the present cases demonstrate a favorable outcome of the revascularization procedure in immature necrotic molars by using calcium hydroxide medication in the coronal third of the root canals. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Hydrogen uptake characteristics of mischmetal based alloy

NASA Astrophysics Data System (ADS)

Jain, Ankur; Jain, R. K.; Jain, I. P.

Hydrogen storage properties of Mm 39.2Ni 42.1Mn 4.9Al 1.25Co 10.2Fe 2.35 alloy have been systematically studied in the present work. An attempt is made to relate the content of hydrogen with change in resistance. It is found that the resistance of material increases with the increase in value of H/ M due to hydrogen absorption. Pressure composition (P-C-T) isotherm using water displacement method has been investigated in the temperature and pressure ranges of 308 ≤ T ≤ 338 K and 0.5 ≤ P ≤ 10 bar, respectively. The P-C isotherms show the presence of two single α and β regions one mixed α + β phase. The maximum H (wt%) was found to be around 1.53 at 308 K and around 6 bar. Since enthalpy is an index of thermochemical stability of metal hydride the thermo dynamical parameters viz., the relative partial molar enthalpy (Δ H) and relative partial molar entropy (Δ S) of dissolved hydrogen have been calculated by plotting the Van't Hoff plot. The variation of Δ H and Δ S with the hydrogen concentration confirm the phase boundaries.

Molar mass, radius of gyration and second virial coefficient from new static light scattering equations for dilute solutions: application to 21 (macro)molecules.

PubMed

Illien, Bertrand; Ying, Ruifeng

2009-05-11

New static light scattering (SLS) equations for dilute binary solutions are derived. Contrarily to the usual SLS equations [Carr-Zimm (CZ)], the new equations have no need for the experimental absolute Rayleigh ratio of a reference liquid and solely rely on the ratio of scattered intensities of solutions and solvent. The new equations, which are based on polarizability equations, take into account the usual refractive index increment partial differential n/partial differential rho(2) complemented by the solvent specific polarizability and a term proportional to the slope of the solution density rho versus the solute mass concentration rho(2) (density increment). Then all the equations are applied to 21 (macro)molecules with a wide range of molar mass (0.2500 kg mol(-1)), for which the scattered intensity is no longer independent of the scattering angle, the new equations give the same value of the radius of gyration as the CZ equation and consistent values of the second virial coefficient.

The e[sup [minus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holroyd, R.A.; Schwarz, H.A.; Stradowska, E.

The rate constants for attachment of excess electrons to 1,3-butadiene (k[sub a]) and detachment from the butadiene anion (k[sub d]) in n-hexane are reported. The equilibrium constant, K[sub eq] = k[sub a]/k[sub d], increases rapidly with pressure and decreases as the temperature increases. At -7[degree]C attachment is observed at 1 bar. At high pressures the attachment rate is diffusion controlled. The activation energy for detachment is about 21 kcal/mol; detachment is facilitated by the large entropy of activation. The reaction volumes for attachment range from -181 cm[sup 3]/mol at 400 bar to-122 cm[sup 3]/mol at 1500 bar and are largelymore » attributed to the electrostriction volume of the butadiene anion ([Delta][bar V][sub el]). Values of [Delta][bar V][sub el] calculated by a model, which includes a glassy shell of solvent molecules around the ion, are in agreement with experimental reaction volumes. The analysis indicates the partial molar volume of the electron in hexane is small and probably negative. It is shown that the entropies of reaction are closely related to the partial molar volumes of reaction. 22 refs., 5 figs., 5 tabs.« less

Partial hydatidiform mole with false-negative urine human chorionic gonadatropin test in the emergency department.

PubMed

Mundangepfupfu, Tichaendepi; Waseem, Muhammad

2014-03-01

Hydatidiform mole (molar pregnancy) is a benign tumor of placental trophoblastic cells, which release human chorionic gonadotropin (hCG). Several case reports have described complete hydatidiform moles with false-negative urine qualitative hCG tests. These negative pregnancy tests have been attributed to the hook effect. We report an unusual presentation of a partial mole and review an alternative explanation for the negative hCG test. As partial moles are usually not associated with a large proliferation of trophoblastic cells, levels of hCG are commonly < 100,000 mIU/mL. The most common presentation of a hydatidiform mole is vaginal bleeding. Hydatidiform mole is associated with a risk of malignant transformation and disseminated disease. In a pregnant patient, vaginal bleeding and abdominal pain are common presentations. Molar pregnancy is an uncommon cause of abdominal pain and vaginal bleeding that should be considered. A 47-year-old female presented to the emergency department with abdominal pain and vaginal bleeding. Urine qualitative hCG was negative and serum quantitative hCG was 1,094,950 mIU/mL. Pelvic ultrasonography showed a uterine cavity containing a soft-tissue mass with multiple cystic lesions and the hydatidiform mole was extracted with suction curettage. Tissue pathology confirmed partial hydatidiform mole. In addition to the hook effect, we present another possible explanation for the false-negative test; namely the inability of some assays to detect hCG-degradation products, which may be higher in clinical samples from patients with hydatidiform mole. This case underscores the importance of knowing the limitations of the commonly used hCG assays. Copyright © 2014 Elsevier Inc. All rights reserved.

Physicochemical Behavior of Some Amino Acids/Glycylglycine in Aqueous D-Galactose Solutions at Different Temperatures

NASA Astrophysics Data System (ADS)

Ali, Anwar; Patel, Rajan; Shahjahan; Ansari, Nizamul Haque

2010-03-01

The apparent molar volumes {(overline{V_2})} for glycine (Gly), l-alanine (Ala), phenylalanine (Phe), and glycylglycine (Gly-Gly) in 0.10 m aqueous d-galactose solutions have been determined from density measurements at (298.15, 303.15, 308.15, and 313.15) K. The data for {(overline{V_2})} were utilized to estimate the partial molar volume at infinite dilution {(overline{V_2^0})} , and experimental slope {(S_v^ast)} . The transfer volume, {(overline{V2^0}_(tr))} , and hydration number, ( n H) were also evaluated. The viscosity data were used to evaluate A- and B-coefficients of the Jones-Dole equation, the free energy of activation of viscous flow per mole of the solvent {left(Δ μ1^{0ast} right)} and the solute {left(Δ μ 2^{0ast} right)} . The molar refractivity ( R D) was calculated from refractive index data. The results were discussed in terms of hydrophilic-ionic, hydrophilic-hydrophobic, and hydrophobic-hydrophobic interactions, and structure-making/-breaking ability of the solute (AAs/peptide) in aqueous d-galactose solutions.

Ultrasonic speed, densities and viscosities of xylitol in water and in aqueous tyrosine and phenylalanine solutions at different temperatures

NASA Astrophysics Data System (ADS)

Ali, A.; Bidhuri, P.; Uzair, S.

2014-07-01

Ultrasonic speed u, densities ρ and viscosities η of xylitol in water and in 0.001 m aqueous l-tyrosine (Tyr) and l-phenylalanine (Phe) have been measured at different temperatures. From the density and ultrasonic speed measurements apparent molar isentropic compression κ_{φ}, apparent molar isentropic compressions at infinite dilution κ_{{S,φ}}0 , experimental slope S K , hydration number n H , transfer partial molar isentropic compressibility Δ_{tr} κ_{{S,φ}}0 of xylitol from water to aqueous Tyr and Phe have been obtained. From the viscosity data, B-coefficient and B-coefficient of transfer Δ tr B of xylitol from water to aqueous Phe and Tyr at different temperatures have also been estimated. Gibbs free energies of activation of viscous flow per mole of solvent Δ μ 1 0# and per mole of solute Δ μ 2 0# have been calculated by using Feakins transition state theory for the studied systems. The calculated parameters have been interpreted in terms of solute-solute and solute-solvent interactions and hydration behavior of xylitol.

[Determination of the solubility parameter of organosolv lignin by inverse gas chromatography].

PubMed

Yu, Yachen; Li, Kunlan; Ma, Yingchong; Wei, Ligang

2013-02-01

An inverse gas chromatographic (IGC) method has been used to measure the solubility parameters (delta2) of organosolv lignin at the absolute temperatures from 333.15 K to 373.15 K. The test probe solvents were n-octane (n-C8), n-decane (n-C10), n-dodecane (n-C12), and n-tetradecane (n-C14). The specific retention volumes of the solvents (Vg0), the molar enthalpy of sorption (deltaH1S), the partial molar enthalpy of mixing at infinite dilution (deltaH1infinity), the molar enthalpy of vaporization (deltaHv), the activity coefficients at infinite dilution (Omega1- infinity), and Flory-Huggins inter action parameters (chi12infinity) between organosolv lignin and probe solvents were obtained. The results showed that the above four probes are poor solvents for organosolv lignin; at the same temperature, the chi12infinity reduced with the increase of the carbon number of probe solvents. The average solubility parameter of organosolv lignin was determined as 19.03 (J x cm(-3))1/2.

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body.

PubMed

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification.

The chronology of third molar mineralization by digital orthopantomography.

PubMed

Maled, Venkatesh; Vishwanath, S B

2016-10-01

The present study was designed to determine the chronology of third molar mineralization to establish Indian reference data and to observe the advantages of digital orthopantomography. Therefore, a cross-sectional study was undertaken by evaluating 167 digital orthopantomographs in order to assess the mineralization status of the mandibular third molar of Caucasian individuals (85 males and 82 females) between the age of 14 and 24. The evaluation was carried out using the 8-stage developmental scheme of Demirjian et al (1973). The range, mean age, standard deviation and Student t-test are presented for each stage of mineralization in all four quadrants. Statistically significant differences between males and females were not found for all four third molars. All the individuals in this study with mature third molar were at least 18 years of age. For medicolegal purposes, the likelihood of whether an Indian is older than 18 years or not was determined. The advantage of digital orthopantomography in the interpretation of the tooth mineralization over the traditional method was acknowledged. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myint, P. C.; Hao, Y.; Firoozabadi, A.

2015-03-27

Thermodynamic property calculations of mixtures containing carbon dioxide (CO 2) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data [1]. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi [2], and the CO 2 activity coefficient model by Duanmore » and Sun [3]. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO 2, pure water, and both CO 2-rich and aqueous (H 2O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Sun’s model yields accurate results for the partial molar enthalpy of CO 2. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H 2O-CO 2-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.« less

Triple paternal contribution to a normal/complete molar chimeric singleton placenta.

PubMed

Ariel, I; Goldman-Wohl, D; Yagel, S; Gazit, E; Loewenthal, R

2017-05-01

A comprehensive study of unusual cases of placental pathology may provide insight into mechanisms of normal human fertilization and early embryonic development by examining the exception to the rule. A gravida three para two 39-year-old woman was monitored by ultrasound from 16 weeks of gestation for cystic placenta. A female newborn was born at 36 weeks gestation. Pathologic examination of the partially cystic placenta revealed a singleton placenta comprised of 2/3 normal placenta and 1/3 complete hydatidiform mole, largely degenerated. Immunostaining for p57 was negative in stromal cells of the molar villi. Chromogenic in-situ hybridization revealed diploidy in both normal and molar parts. A total of 16 microsatellites were studied by short tandem repeat analysis, 11 of which were informative. The analysis revealed bipaternal molar tissue of dispermic origin. The paternal monospermic contribution to the normal part was different from that in the molar part, thus resulting in tripaternal contribution to the conceptus. A chimera is a single organism composed of two or more different populations of genetically distinct cells that originated from different zygotes (tetragametic) whereas mosaic is a mixture of two cell lines in one organism originating from one zygote. The possible mechanisms leading to the formation of chimeric/mosaic placenta in our case (one of the components being complete hydatidiform mole), including twinning, fusion at an early embryonic stage and diploidization of triploids, are discussed. © The Author 2017. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Reconstructing temporal variation of fluoride uptake in eastern grey kangaroos (Macropus giganteus) from a high-fluoride area by analysis of fluoride distribution in dentine.

PubMed

Kierdorf, Horst; Rhede, Dieter; Death, Clare; Hufschmid, Jasmin; Kierdorf, Uwe

2016-04-01

Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Partial Pressures of Te2 and Thermodynamic Properties of Ga-Te System

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

2001-01-01

The partial pressures of Te2 in equilibrium with Ga(1-x)Te(x) samples were measured by optical absorption technique from 450 to 1100 C for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te, and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's Law constants. The partial pressures of Te2 in equilibrium with the GaTe(s) and Ga2Te3(s)compounds, or the so-called three-phase curves, were established. These partial pressure data imply the existence of the Ga3Te4(s) compound. From the partial pressures of Te2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonable well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te2. These data agree well with most of the previous results. The possible reason for the high activity of Te measured for x less than 0.60 is discussed.

Random forest models to predict aqueous solubility.

PubMed

Palmer, David S; O'Boyle, Noel M; Glen, Robert C; Mitchell, John B O

2007-01-01

Random Forest regression (RF), Partial-Least-Squares (PLS) regression, Support Vector Machines (SVM), and Artificial Neural Networks (ANN) were used to develop QSPR models for the prediction of aqueous solubility, based on experimental data for 988 organic molecules. The Random Forest regression model predicted aqueous solubility more accurately than those created by PLS, SVM, and ANN and offered methods for automatic descriptor selection, an assessment of descriptor importance, and an in-parallel measure of predictive ability, all of which serve to recommend its use. The prediction of log molar solubility for an external test set of 330 molecules that are solid at 25 degrees C gave an r2 = 0.89 and RMSE = 0.69 log S units. For a standard data set selected from the literature, the model performed well with respect to other documented methods. Finally, the diversity of the training and test sets are compared to the chemical space occupied by molecules in the MDL drug data report, on the basis of molecular descriptors selected by the regression analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakshit, S.K.; Naik, Y.P.; Parida, S.C.

Three ternary oxides LiAl{sub 5}O{sub 8}(s), LiAlO{sub 2}(s) and Li{sub 5}AlO{sub 4}(s) in the system Li-Al-O were prepared by solid-state reaction route and characterized by X-ray powder diffraction method. Equilibrium partial pressure of CO{sub 2}(g) over the three-phase mixtures {l_brace}LiAl{sub 5}O{sub 8}(s)+Li{sub 2}CO{sub 3}(s)+5Al{sub 2}O{sub 3}(s){r_brace}, {l_brace}LiAl{sub 5}O{sub 8}(s)+5LiAlO{sub 2}(s)+2Li{sub 2}CO{sub 3}(s){r_brace} and {l_brace}LiAlO{sub 2}(s)+Li{sub 5}AlO{sub 4}(s)+2Li{sub 2}CO{sub 3}(s){r_brace} were measured using Knudsen effusion quadrupole mass spectrometry (KEQMS). Solid-state galvanic cell technique based on calcium fluoride electrolyte was used to determine the standard molar Gibbs energies of formations of these aluminates. The standard molar Gibbs energies of formation of thesemore » three aluminates calculated from KEQMS and galvanic cell measurements were in good agreement. Heat capacities of individual ternary oxides were measured from 127 to 868 K using differential scanning calorimetry. Thermodynamic tables representing the values of {delta}{sub f}H{sup 0}(298.15 K), S{sup 0}(298.15 K) S{sup 0}(T), C{sub p}{sup 0}(T), H{sup 0}(T), {l_brace}H{sup 0}(T)-H{sup 0}(298.15 K){r_brace}, G{sup 0}(T), {delta}{sub f}H{sup 0}(T), {delta}{sub f}G{sup 0}(T) and free energy function (fef) were constructed using second law analysis and FACTSAGE thermo-chemical database software. - Graphical abstract: Comparison of {delta}{sub f}G{sub m}{sup 0} of ternary oxides determined from KEQMS and solid-state galvanic cell techniques. (O) KEQMS, (9632;) solid-state galvanic cell and solid line: combined fit of both the experimental data.« less

Comparison of K-loop Molar Distalization with that of Pendulum Appliance - A Prospective Comparative Study.

PubMed

Shashidhar, Nagam Reddy; Reddy, S Rama Koteswara; Rachala, Madhukar Reddy

2016-06-01

Molar distalization is the non extraction method of managing Class II malocclusions. The purpose of this study was to evaluate the skeletal and dentoalveolar effects of maxillary molar distalization with K-loop appliance, and to compare these effects with that of pendulum group. Class I and dental Class II malocclusions were divided into two groups of 15 each: In Group 1 (nine females and six males; mean age, 16.0±2.6 years) patients were treated with K-Loop molar distalization supported palatally by Nance button, while in Group 2 (seven females and eight males; mean age, 15.4±4.7 years), the patients were treated with conventional pendulum appliance. Standardized lateral cephalograms were taken at the beginning of treatment (T0) and at the end of molar distalization (T1) and the changes were statistically analyzed with paired t-test. The results showed no statistically significant difference in the amount of molar distalization in either of the appliance groups: the mean amount of molar distal movement of 5.1±0.8 mm and 4.93±1.68 mm was observed in the Group 1 and 2 respectively. The incisors moved mesially by 1.3±0.63 mm in Group 1 and 1.57±0.58 mm in Group 2. K-Loop molar distalizing appliance has similar skeletal and dentoalveolar effects as that of pendulum appliance, with the advantages of simple yet efficient to control the moment-force ratio to produce all types of tooth movements and also requires minimal patient co-operation.

Assessment of the potential of Allium sativum oil as a new medicament for non-vital pulpotomy of primary teeth

PubMed Central

Mohammad, Shukry Gamal; Baroudi, Kusai

2015-01-01

Objective: The objective of this study was to compare the clinical and radiographic effects of Allium sativum oil and formocresol in nonvital pulpotomy in primary teeth. Materials and Methods: Twenty children ranging in age from 4 to 8 years were included in the study. In every one of those children, pulpotomy was indicated for the primary molars. Pulpotomy procedure was performed and the radicular pulp tissue of one molar was capped with A. sativum oil in a cotton pellet while the other molar was capped with formocresol. The teeth were evaluated clinically and radiographically before and after 6 months using standard clinical and radiographic criteria. Statistically, these results revealed significant difference between the radiographic findings of nonvital pulpotomy in primary molars with the two medicaments. Statistical analysis was performed using independent t-test and paired t-test at the significance level of α = 0.05. Results: A. sativum oil has potent antibacterial properties that enable it to combat intracanal microbes in the infected pulp of primary molars. Better results were obtained when A. sativum oil was used. Conclusion: A. sativum oil had more powerful effects than formocresol on the infected pulp of primary nonvital molars. PMID:26312232

Pulp/tooth ratio of mandibular first and second molars on panoramic radiographs: An aid for forensic age estimation

PubMed Central

Shah, Palak H.; Venkatesh, Rashmi

2016-01-01

Objective: To determine and compare the accuracy of pulp/tooth ratio method in mandibular first and second molar teeth in forensic age estimation. Materials and Methods: A total 300 panoramic radiographs of the Gujarati population (187 males and 113 females) were studied. The measurements of Pulp Chamber Height (PCH) and Crown Root Trunk Height (CRTH) were performed on the mandibular first and second molar teeth. The acquired data was subjected to correlation and regression. Results: The pulp chamber crown root trunk height ratios (PCTHR) of both the first (r = −0.609) and second molars (r = −0.422) were significantly correlated with the age of the individual. Individual regression formulae were derived for both the teeth which were then used separately to calculate the age. The standard errors estimate (SEE) for the first and second molars were 8.84 years and 10.11 years, respectively. There was no statistically significant difference between chronological and calculated age by both the teeth (P = 1.000). Conclusion: The mandibular first and second molar is a potential tool for age estimation in forensic dentistry. The pulp/tooth ratio of both the teeth is a useful method for forensic age prediction with reasonable accuracy in the Gujarati population. PMID:27555734

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Potassium Benzoate C7H5O2K(s)

NASA Astrophysics Data System (ADS)

Yang, Wei-Wei; di, You-Ying; Yin, Zhen-Fen; Kong, Yu-Xia; Tan, Zhi-Cheng

2009-04-01

Potassium benzoate C7H5O2K (CAS Registry No. 582-25-2) was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction (XRD) techniques were applied to characterize the composition and structure of the compound. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by the least-squares method. Smoothed heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial. In accordance with Hess’s law, a reasonable thermochemical cycle was designed, and 100 mL of 1 mol · dm-3 NaOH solution was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the title compound C7H5O2K (s) was derived to be -(610.94 ± 0.77) kJ · mol-1.

Synthesis of Non-Toxic Silica Particles Stabilized by Molecular Complex Oleic-Acid/Sodium Oleate

PubMed Central

Spataru, Catalin Ilie; Ianchis, Raluca; Petcu, Cristian; Nistor, Cristina Lavinia; Purcar, Violeta; Trica, Bogdan; Nitu, Sabina Georgiana; Somoghi, Raluca; Alexandrescu, Elvira; Oancea, Florin; Donescu, Dan

2016-01-01

The present work is focused on the preparation of biocompatible silica particles from sodium silicate, stabilized by a vesicular system containing oleic acid (OLA) and its alkaline salt (OLANa). Silica nanoparticles were generated by the partial neutralization of oleic acid (OLA), with the sodium cation present in the aqueous solutions of sodium silicate. At the molar ratio OLA/Na+ = 2:1, the molar ratio (OLA/OLANa = 1:1) required to form vesicles, in which the carboxyl and carboxylate groups have equal concentrations, was achieved. In order to obtain hydrophobically modified silica particles, octadecyltriethoxysilane (ODTES) was added in a sodium silicate sol–gel mixture at different molar ratios. The interactions between the octadecyl groups from the modified silica and the oleyl chains from the OLA/OLANa stabilizing system were investigated via simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) (TG-DSC) analyses.A significant decrease in vaporization enthalpy and an increase in amount of ODTES were observed. Additionally, that the hydrophobic interaction between OLA and ODTES has a strong impact on the hybrids’ final morphology and on their textural characteristics was revealed. The highest hydrodynamic average diameter and the most negative ζ potential were recorded for the hybrid in which the ODTES/sodium silicate molar ratio was 1:5. The obtained mesoporous silica particles, stabilized by the OLA/OLANa vesicular system, may find application as carriers for hydrophobic bioactive molecules. PMID:27869768

Morphoregulation of teeth: modulating the number, size, shape and differentiation by tuning Bmp activity

PubMed Central

Plikus, Maksim V.; Zeichner-David, Maggie; Mayer, Julie-Ann; Reyna, Julia; Bringas, Pablo; Thewissen, J. G. M.; Snead, Malcolm L.; Chai, Yang; Chuong, Cheng-Ming

2015-01-01

SUMMARY During development and evolution, the morphology of ectodermal organs can be modulated so that an organism can adapt to different environments. We have proposed that morphoregulation can be achieved by simply tilting the balance of molecular activity. We test the principles by analyzing the effects of partial downregulation of Bmp signaling in oral and dental epithelia of the keratin 14-Noggin transgenic mouse. We observed a wide spectrum of tooth phenotypes. The dental formula changed from 1.0.0.3/1.0.0.3 to 1.0.0.2(1)/1.0.0.0. All mandibular and M3 maxillary molars were selectively lost because of the developmental block at the early bud stage. First and second maxillary molars were reduced in size, exhibited altered crown patterns, and failed to form multiple roots. In these mice, incisors were not transformed into molars. Histogenesis and differentiation of ameloblasts and odontoblasts in molars and incisors were abnormal. Lack of enamel caused misocclusion of incisors, leading to deformation and enlargement in size. Therefore, subtle differences in the level, distribution, and timing of signaling molecules can have major morphoregulatory consequences. Modulation of Bmp signaling exemplifies morphoregulation hypothesis: simple alteration of key signaling pathways can be used to transform a prototypical conical-shaped tooth into one with complex morphology. The involvement of related pathways and the implication of morphoregulation in tooth evolution are discussed. PMID:16174037

Structures and standard molar enthalpies of formation of a series of Ln(III)–Cu(II) heteronuclear compounds with pyrazine-2,3-dicarboxylic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qi; Xie, Gang; Wei, Qing

2014-07-01

Fifteen lanthanide–copper heteronuclear compounds, formulated as [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 6}]·xH{sub 2}O (1–6(x=2), 8(x=3), 9–10(x=4)); [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 4}]·xH{sub 2}O (7, 12–13, 15(x=4), 14(x=5), 11(x=8)) (Ln(III)=La(1); Ce(2); Pr(3); Nd(4); Sm(5); Eu(6); Gd(7); Tb(8); Dy(9); Ho(10); Er(11); Tm(12); Yb(13); Lu(14); Y(15); H{sub 2}pzdc (C{sub 6}H{sub 4}N{sub 2}O{sub 4})=pyrazine-2,3-dicarboxylic acid) have been hydrothermally synthesized. All compounds were characterized by element analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analyses confirm that all compounds are isostructural and feature a 3D brick-like framework structure with (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 2}.8{sup 2})(6{sup 3}){sup 2}(6{sup 5}.8){sub 2} topology. Using 1 mol cm{supmore » −3} HCl(aq) as calorimetric solvent, with an isoperibol solution–reaction calorimeter, the standard molar enthalpies of formation of all compounds were determined by a designed thermochemical cycle. In addition, solid state luminescence properties of compounds 5, 6, 8 and 9 were studied in the solid state. - Graphical abstract: According to Hess' rule, the standard molar enthalpies of formation of Ln–Cu heterometallic coordination compounds were determined by a designed thermochemical cycle. - Highlights: • Fifteen lanthanide–copper heteronuclear isostructural compounds. • Structurally characterization by IR, X-ray diffraction and thermal analysis. • The standard molar enthalpy of formation. • Isoperibol solution–reaction calorimetry.« less

Morphological study on dental caries induced in WBN/KobSlc rats (Rattus norvegicus) fed a standard laboratory diet.

PubMed

Fukuzato, Yoko; Matsuura, Tetsuro; Ozaki, Kiyokazu; Matsuura, Masahiro; Sano, Tomoya; Nakahara, Yutaka; Kodama, Yasushi; Nakagawa, Akihito; Okamura, Sumie; Suido, Hirohisa; Torii, Kayo; Makino, Taketoshi; Narama, Isao

2009-10-01

In our previous studies, WBN/KobSlc was characterized as a rat strain in which only males began to develop pancreatitis, and then presented with diabetic symptoms. In the course of studying their pancreatic inflammation, we detected molar caries in prediabetic males feeding on a standard diet (CRF-1) widely used for experimental animals. The purpose of this study is to confirm whether the WBN/KobSlc strain is caries-susceptible to the diet reported to be non-cariogenic, and to examine the effect of a prediabetic condition on their dental caries. For a morphological study, 25 male WBN/KobSlc rats aged 3.2-7.8 months and 24 females of the same strain aged 3.3-6.6 months were used, along with 10 males and 10 females of 8.2-month-old F344 rats. Marked dental caries were detected in the mandibular molars of male and female WBN/KobSlc rats regardless of pancreatitis, although no similar changes were observed in any teeth of the F344 strain fed the same diet. Soft X-ray examination revealed that the caries began in the crown and progressed horizontally and vertically, and that a severe radiolucent lesion extensively expanded to the entire crown, corresponding to a macroscopically deleted molar. The caries had gradually developed mainly in the second mandibular molar from more than 3.5 months of age, while none were seen in any rats before that time. The WBN/KobSlc rats were caries-susceptible even to the standard laboratory diet, and pancreatitis was not directly associated with the onset of dental caries in this strain.

[Evaluation of accuracy of virtual occlusal definition in Angle class I molar relationship].

PubMed

Wu, L; Liu, X J; Li, Z L; Wang, X

2018-02-18

To evaluate the accuracy of virtual occlusal definition in non-Angle class I molar relationship, and to evaluate the clinical feasibility. Twenty pairs of models of orthognathic patients were included in this study. The inclusion criteria were: (1) finished with pre-surgical orthodontic treatment and (2) stable final occlusion. The exclusion criteria were: (1) existence of distorted teeth, (2) needs for segmentation, (3) defect of dentition except for orthodontic extraction ones, and (4) existence of tooth space. The tooth-extracted test group included 10 models with two premolars extracted during preoperative orthodontic treatment. Their molar relationships were not Angle class I relationship. The non-tooth-extracted test group included another 10 models without teeth extracted, therefore their molar relationships were Angle class I. To define the final occlusion in virtual environment, two steps were included: (1) The morphology data of upper and lower dentition were digitalized by surface scanner (Smart Optics/Activity 102; Model-Tray GmbH, Hamburg, Germany); (2) the virtual relationships were defined using 3Shape software. The control standard of final occlusion was manually defined using gypsum models and then digitalized by surface scanner. The final occlusion of test group and control standard were overlapped according to lower dentition morphology. Errors were evaluated by calculating the distance between the corresponding reference points of testing group and control standard locations. The overall errors for upper dentition between test group and control standard location were (0.51±0.18) mm in non-tooth-extracted test group and (0.60±0.36) mm in tooth-extracted test group. The errors were significantly different between these two test groups (P<0.05). However, in both test groups, the errors of each tooth in a single dentition does not differ from one another. There was no significant difference between errors in tooth-extracted test group and 1 mm (P>0.05); and the accuracy of non-tooth-extracted group was significantly smaller than 1 mm (P<0.05). The error of virtual occlusal definition of none class I molar relationship is higher than that of class I relationship, with an accuracy of 1 mm. However, its accuracy is still feasible for clinical application.

The use of fixed appliances in the UK: a survey of specialist orthodontists.

PubMed

Banks, Phil; Elton, Victoria; Jones, Yvonne; Rice, Peter; Derwent, Serena; Odondi, Lang'o

2010-03-01

To investigate the use of fixed appliances in the UK. Prospective postal questionnaire. UK. All members of the General Dental Council Specialist List in Orthodontics still in active practice and not in training posts. A preemptive letter of explanation was sent inviting orthodontists to participate in the survey. The questionnaire was subsequently posted to 935 specialists. Data analysis investigated differences in clinical practice related to varying provider groups, level of operator experience and geographical region. The response rate achieved was 66.3%. A majority of orthodontists routinely used the 0.022 inch pre-adjusted edgewise system, standard size Siamese pattern stainless steel brackets, conventionally ligated and bonded using standard etch and light cured composite. Nickel titanium and stainless steel were the most popular archwire materials. Anchorage was supported routinely by palatal and lingual arches in up to 25% and by headgear in over a third of respondents. Newer innovations showed variable popularity. Self-etching primer was used routinely by one-third of respondents with 11% use of self-ligating brackets. Banding of first molars was preferred by over 60% of clinicians. Bone screw implants were used by only 0.2% of respondents. Clinicians with less than 10 years experience used more headgear, light curing, MBT prescription and molar bonding. Operators with over 20 years experience used more chemically cured bonding, Roth prescription, banded first molars, 0.018 inch slot size and Tip-Edge(TM), with less use of headgear. Fixed appliance use differed from that reported in the US with lower use in the UK of standard edgewise and Roth systems, aesthetic, miniaturised and 0.018 inch slot brackets and rapid maxillary expansion. Most UK orthodontic specialists routinely used the 0.022 inch pre-adjusted edgewise system with standard size Siamese steel brackets bonded using standard etch and light cured composite with conventional ligation. Variations were seen between different provider groups, types of treatment funding, levels of operator seniority and geographical regions. Differences were noted particularly in the use of bracket prescription and design, types of molar attachment and anchorage control.

The Prophylactic Extraction of Third Molars: A Public Health Hazard

PubMed Central

Friedman, Jay W.

2007-01-01

Ten million third molars (wisdom teeth) are extracted from approximately 5 million people in the United States each year at an annual cost of over $3 billion. In addition, more than 11 million patient days of “standard discomfort or disability”—pain, swelling, bruising, and malaise—result postoperatively, and more than 11000 people suffer permanent paresthesia—numbness of the lip, tongue, and cheek—as a consequence of nerve injury during the surgery. At least two thirds of these extractions, associated costs, and injuries are unnecessary, constituting a silent epidemic of iatrogenic injury that afflicts tens of thousands of people with lifelong discomfort and disability. Avoidance of prophylactic extraction of third molars can prevent this public health hazard. PMID:17666691

Comparison of the Relative Risk of Molar Root Perforations Using Various Endodontic Instrumentation Techniques.

DTIC Science & Technology

1983-03-01

sodium hypochlorite using a standard endodontic irrigating syringe (Monoject Endodontic Syringe, Sherwood Medical Co., St. Louis, MO), and the...the sample. The Joel R. Kessler 8 teeth were placed in a 5.25% sodium hypochlorite solution for 30 minutes in order to remove soft tissue on the root...molars. J Endodon 1975;1:211-14. 7. Senia ES, Marshall FJ, Rosen S. The solvent action of sodium hypochlorite on pulp tissue of extracted teeth. Oral

Comparison of K-loop Molar Distalization with that of Pendulum Appliance - A Prospective Comparative Study

PubMed Central

Shashidhar, Nagam Reddy; Reddy, S.Rama Koteswara

2016-01-01

Introduction Molar distalization is the non extraction method of managing Class II malocclusions. Aim The purpose of this study was to evaluate the skeletal and dentoalveolar effects of maxillary molar distalization with K-loop appliance, and to compare these effects with that of pendulum group. Materials and Methods Class I and dental Class II malocclusions were divided into two groups of 15 each: In Group 1 (nine females and six males; mean age, 16.0±2.6 years) patients were treated with K-Loop molar distalization supported palatally by Nance button, while in Group 2 (seven females and eight males; mean age, 15.4±4.7 years), the patients were treated with conventional pendulum appliance. Standardized lateral cephalograms were taken at the beginning of treatment (T0) and at the end of molar distalization (T1) and the changes were statistically analyzed with paired t-test. Results The results showed no statistically significant difference in the amount of molar distalization in either of the appliance groups: the mean amount of molar distal movement of 5.1±0.8 mm and 4.93±1.68 mm was observed in the Group 1 and 2 respectively. The incisors moved mesially by 1.3±0.63 mm in Group 1 and 1.57±0.58 mm in Group 2. Conclusion K-Loop molar distalizing appliance has similar skeletal and dentoalveolar effects as that of pendulum appliance, with the advantages of simple yet efficient to control the moment-force ratio to produce all types of tooth movements and also requires minimal patient co-operation. PMID:27504403

Influence of unilateral maxillary first molar extraction treatment on second and third molar inclination in Class II subdivision patients.

PubMed

Livas, Christos; Pandis, Nikolaos; Booij, Johan Willem; Halazonetis, Demetrios J; Katsaros, Christos; Ren, Yijin

2016-01-01

To assess the maxillary second molar (M2) and third molar (M3) inclination following orthodontic treatment of Class II subdivision malocclusion with unilateral maxillary first molar (M1) extraction. Panoramic radiographs of 21 Class II subdivision adolescents (eight boys, 13 girls; mean age, 12.8 years; standard deviation, 1.7 years) before treatment, after treatment with extraction of one maxillary first molar and Begg appliances and after at least 1.8 years in retention were retrospectively collected from a private practice. M2 and M3 inclination angles (M2/ITP, M2/IOP, M3/ITP, M3/IOP), constructed by intertuberosity (ITP) and interorbital planes (IOP), were calculated for the extracted and nonextracted segments. Random effects regression analysis was performed to evaluate the effect on the molar angulation of extraction, time, and gender after adjusting for baseline measurements. Time and extraction status were significant predictors for M2 angulation. M2/ITP and M2/IOP decreased by 4.04 (95% confidence interval [CI]: -6.93, 1.16; P  =  .001) and 3.67 (95% CI: -6.76, -0.58; P  =  .020) in the extraction group compared to the nonextraction group after adjusting for time and gender. The adjusted analysis showed that extraction was the only predictor for M3 angulation that reached statistical significance. M3 mesial inclination increased by 7.38° (95% CI: -11.2, -3.54; P < .001) and 7.33° (95% CI: -11.48, -3.19; P  =  .001). M2 and M3 uprighting significantly improved in the extraction side after orthodontic treatment with unilateral maxillary M1 extraction. There was a significant increase in mesial tipping of maxillary second molar crowns over time.

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body

PubMed Central

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

Aim: To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Materials and Methods: Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. Results: The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Conclusion: Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification. PMID:26005300

Optical high acidity sensor

DOEpatents

Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

1997-01-01

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

Optical high acidity sensor

DOEpatents

Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

1997-07-22

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

Microleakage of stainless steel crowns placed on intact and extensively destroyed primary first molars: an in vitro study.

PubMed

Seraj, Bahman; Shahrabi, Mahdi; Motahari, Pouria; Ahmadi, Rahil; Ghadimi, Sara; Mosharafian, Shahram; Mohammadi, Kaveh; Javad Kharazifard, Mohammad

2011-01-01

The purpose of this investigation was to evaluate the effect of residual tooth structure on the microleakage of stainless steel crowns cemented with glass ionomer on primary maxillary and mandibular first molars. Thirty extracted primary molars were divided into 2 groups: group 1 included intact teeth; and group 2 included extensively carious samples. Each tooth received standard preparation, and each crown was luted with G-CEM on its specific specimen. Teeth were loaded vertically and transferred to distilled water. After thermocycling and immersing in methylene blue solution, the teeth were sectioned and examined microscopically for microleakage. Data were analyzed using Mann-Whitney U and Wilcoxon signed-rank tests. All specimens (intact and damaged teeth) had microleakage, although most of these presented only minimum microleakage. No statistically significant differences were found in the microleakage of sound and extensively carious teeth on either the buccal (P=.62) or lingual (P=.65) side. Buccal (P=.73) and lingual (P=.63) surfaces showed similar microleakage scores in primary maxillary and mandibular molars. There was no significant difference in the microleakage of sound or extensively carious teeth and primary maxillary or mandibular first molars.

Dental age estimation in living individuals using 3.0 T MRI of lower third molars.

PubMed

Guo, Yucheng; Olze, Andreas; Ottow, Christian; Schmidt, Sven; Schulz, Ronald; Heindel, Walter; Pfeiffer, Heidi; Vieth, Volker; Schmeling, Andreas

2015-11-01

In order to increase the validity of age estimation in adolescents and young adults when there is no legitimation for X-ray examinations, it seems desirable to be able to assess the mineralization of third molars using X-ray-free imaging procedures. In the present study, the mineralization stages of lower third molars were determined prospectively in 269 male and 248 female individuals aged 12 to 24 years using 3.0 T MRI. The classification system of Demirjian et al. was used to determine the stages. This study presents the minima and maxima, means and standard deviations, median values, and lower and upper quartiles separately for both sexes, for the mineralization stages B-H. Statistically significant sex differences were observed for the mineralization stages C, E, F, and G, and a faster developmental rate was observed for males. It was concluded that magnetic resonance imaging is an X-ray-free alternative to orthopantomography when assessing mineralization of third molars.

Endodontic Microsurgical Treatment of a Three-rooted Mandibular First Molar with Separate Distolingual Root: Report of One Case.

PubMed

Wang, Han Guo; Xu, Ning; Yu, Qing

The separate distolingual (DL) roots of three-rooted mandibular first molars are thought to be too difficult for performing apical surgery. This article represents microsurgical treatment of a three-rooted mandibular first molar with a separate DL root. The procedure includes incision and flap retraction, osteotomy, apicoectomy, retropreparation and retrofilling of the root canal, using micro instruments, ultrasonic retrotips and mineral trioxide aggregate (MTA) under a dental operating microscope. Two mm in length of apical root resection, 2 mm in depth of root canal retropreparation with a personalised ultrasonic retrotip, and 2 mm in length of retrofilling with MTA are the key points for accomplishment of apical surgery on separate DL roots. The case was followed up for 15 months after surgery. Clinical and radiographic examinations revealed complete healing of periapical tissue. Separate DL roots of three-rooted mandibular first molars can be treated by endodontic microsurgery with modifications from standard protocol.

Boiling points of halogenated ethanes: an explanatory model implicating weak intermolecular hydrogen-halogen bonding.

PubMed

Beauchamp, Guy

2008-10-23

This study explores via structural clues the influence of weak intermolecular hydrogen-halogen bonds on the boiling point of halogenated ethanes. The plot of boiling points of 86 halogenated ethanes versus the molar refraction (linked to polarizability) reveals a series of straight lines, each corresponding to one of nine possible arrangements of hydrogen and halogen atoms on the two-carbon skeleton. A multiple linear regression model of the boiling points could be designed based on molar refraction and subgroup structure as independent variables (R(2) = 0.995, standard error of boiling point 4.2 degrees C). The model is discussed in view of the fact that molar refraction can account for approximately 83.0% of the observed variation in boiling point, while 16.5% could be ascribed to weak C-X...H-C intermolecular interactions. The difference in the observed boiling point of molecules having similar molar refraction values but differing in hydrogen-halogen intermolecular bonds can reach as much as 90 degrees C.

Oxygen stoichiometry, phase stability, and thermodynamic behavior of the lead-doped and lead-free Bi-2212 systems

NASA Astrophysics Data System (ADS)

Tetenbaum, M.; Hash, M.; Tani, B. S.; Maroni, V. A.

1996-02-01

Electromotive-force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on lead-doped and lead-free Bi 2- zPb zSr 2Ca 1Cu 2O x superconducting ceramics in the temperature range ≈ 700-815°C by means of an oxygen-titration techique that employs an yttria-stabilized zirconia electrolyte. Equations for the variation of oxygen partial pressure with composition and temperature have been derived from our EMF measurements. Thermodynamic assessments of the partial molar quantities Δ overlineH(O 2) and Δ overlineS(O 2) for lead-doped Bi-2212 and lead-free Bi-2212 indicate that the solid-state decomposition of these bismuth cuprates at low oxygen partial pressure can be represented by the diphasic CuOCu 2O system.

Some aspects of the thermodynamic behaviour of the lead-doped Bi-2223 system

NASA Astrophysics Data System (ADS)

Tetenbaum, M.; Maroni, V. A.

1996-02-01

A thermodynamic assessment of lead-doped Bi-2223 with emphasis on compositions and oxygen partial pressures within the homogeneity region prior to solid-state decomposition is presented. Equations for the variation of oxygen partial pressure with composition and temperature have been derived from our EMF measurements. Long-term metastability was indicated during cycling over a temperature range of ∼ 700-815°C of a lead-doped Bi-2223 sample having an oxygen-deficient stoichiometry of 9.64 prior to solid-state decomposition corresponding to the diphasic CuOCu 2O system. A trend of increasing negative values of the partial molar enthalpy Δ overlineH( O 2) and entropy Δ overlineS( O2 with increasing oxygen deficiency of the condensed phase indicated an increase in ordering of the cuprate structure prior to solid-state decomposition.

Cutaneous Sinus Tract from Mandibular Second Molar with C-shaped Canal System and Improper Former Root Canal Treatment: A Case Report.

PubMed

Gharechahi, Maryam; Dastmalchi, Parisa

2016-01-01

Here, we report the diagnosis and treatment of an extraoral cutaneous sinus tract originating in a mandibular second molar with a C-shaped root canal system. The patient was referred to our department by a dermatologist after a series of unsuccessful treatments, including antibiotics. Diffuse radiolucency on a preoperative radiograph revealed that earlier root canal treatment had been only partially successful. Consequently, we performed retreatment of the root canal comprising removal of the former restoration and gutta-percha, cleaning and shaping, and passive irrigation with sodium hypochlorite. The patient responded well, and the cutaneous lesion completely resolved uneventfully within 1 month postoperatively. Preoperative recognition and thorough knowledge of the root canal anatomy and conventional methods of obturation are necessary in performing successful endodontic treatment.

Western Saudi adolescent age estimation utilising third molar development.

PubMed

Alshihri, Amin M; Kruger, Estie; Tennant, Marc

2014-07-01

The aim of this study was to establish reference data on third molar morphology/development for age estimation in Western Saudi adolescents, between ages 14 and 23 years of old. The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. Mean ages, standard deviations, and percentile distributions are presented for each stage of development. The mean estimated age for all participants (n = 130) was 219.7 months, and this differed significantly (P < 0.05) from the mean chronological age (226.5 months). Deviations of predicted age from real age showed 28.5% of all participants had their age estimated within 1 year (±12 months) of their chronological age. Most (43%) had their age underestimated by more than 12 months and the remaining 28.5% had their age overestimated by more than 12 months of their chronological age. Differences in left-right symmetry information of third molars were detected and were higher in the maxilla (92%) than in the mandible (82%). For all molars reaching stage "H" most individuals (males and females) were over the age 18 years of old. Males reach the developmental stages earlier than females. Third molar tooth development can be reliably used to generate mean age and the estimated age range for an individual of unknown chronological age. Further studies with large populations are needed for better statistical results.

The Effect of Sodium Hydroxide Molarity on Strength Development of Non-Cement Class C Fly Ash Geopolymer Mortar

NASA Astrophysics Data System (ADS)

Wardhono, A.

2018-01-01

The use of fly ash as cement replacement material can overcome the environmental issues, especially the global warming problem caused by the greenhouse effect. This is attributed to the CO2 gas produced during the cement manufacturing process, which 1 ton of cement is equivalent to 1 ton CO2. However, the major problem of fly ash is the requirement of activators to activate the polymer reactions. The most common activator used in non-cement or geopolymer material is the combination of sodium hydroxide (NaOH) and sodium silicate. This study aims to identify the effect of NaOH molarity as activator on strength development of non-cement class C fly ash geopolymer mortar. The molarity variations of NaOH were 6 Molar (M), 8M, 10M, 12M, 14M and 15M. The compressive strength test was performed at the age of 3, 7 and 28 days in accordance with ASTM standard, and the specimens were cured at room temperature. The results show that the highest compressive strength was achieved by geopolymer mortar with a molarity of 12M. It exhibits a higher strength to that normal mortar at 28 days. However, the use of NaOH molarity more than 12M tends to decrease the strength of non-cement geopolymer mortar specimens.

Vaporization and thermodynamics of forsterite-rich olivine and some implications for silicate atmospheres of hot rocky exoplanets

NASA Astrophysics Data System (ADS)

Costa, Gustavo C. C.; Jacobson, Nathan S.; Fegley, Bruce, Jr.

2017-06-01

We describe an experimental and theoretical study of olivine [Mg2SiO4 (Fo)-Fe2SiO4 (Fa)] vaporization. The vaporization behavior and thermodynamic properties of a fosterite-rich olivine (Fo95Fa5) have been explored by high-temperature Knudsen effusion mass spectrometry (KEMS) from 1750 to 2250 K. The gases observed (in order of decreasing partial pressure) are Fe, SiO, Mg, O2 and O. We measured the solidus temperature (∼2050 K), partial pressures of individual gases, the total vapor pressure, and thermodynamic activities and partial molar enthalpies of MgO, 'FeO', and SiO2 for the Fo95Fa5 olivine. The results are compared to other measurements and models of the olivine system. Our experimental data show olivine vaporizes incongruently. We discuss this system both as a psuedo-binary of Fo-Fa and a psuedo-ternary of MgO-'FeO'-SiO2. Iron/magnesium molar ratios in the sample before (∼0.05) and after (∼0.04) vaporization are consistent with the small positive deviations from ideality of fayalite (γ ∼ 1.17) in olivine of the composition studied (e.g., Nafziger and Muan, 1967). Our data for olivine + melt confirm prior theoretical models predicting fractional vaporization of Fe relative to Mg from molten silicates (Fegley and Cameron, 1987; Schaefer and Fegley, 2009; Ito et al., 2015). If loss of silicate atmospheres occurs from hot rocky exoplanets with magma oceans the residual planet may be enriched in magnesium relative to iron.

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

PubMed

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

2013-12-28

The partial molar volumes, 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. V(i) is determined with the direct method, while the composition of 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 V(i) deviate only 3.4 cm(3) mol(-1) (7.1%) from experimental literature values. Experimental 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 V(i) variations. In all solutions, larger 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 V(i). Additionally, attractive electrostatic interactions of CO2 and the solvents, which do not depend on internal solvent interactions only, partially reversed the 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 V(i). Overall, the applied methodology reproduces V(i) and its variations reliably and the used V(i) decompositions identify the underlying reasons behind observed V(i) variations.

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)

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

2013-12-01

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.

Fully transparent, non-volatile bipolar resistive memory based on flexible copolyimide films

NASA Astrophysics Data System (ADS)

Yu, Hwan-Chul; Kim, Moon Young; Hong, Minki; Nam, Kiyong; Choi, Ju-Young; Lee, Kwang-Hun; Baeck, Kyoung Koo; Kim, Kyoung-Kook; Cho, Soohaeng; Chung, Chan-Moon

2017-01-01

Partially aliphatic homopolyimides and copolyimides were prepared from rel-(1'R,3S,5'S)-spiro[furan-3(2H),6'-[3]oxabicyclo[3.2.1]octane]-2,2',4',5(4H)-tetrone (DAn), 2,6-diaminoanthracene (AnDA), and 4,4'-oxydianiline (ODA) by varying the molar ratio of AnDA and ODA. We utilized these polyimide films as the resistive switching layer in transparent memory devices. While WORM memory behavior was obtained with the PI-A100-O0-based device (molar feed ratio of DAn : AnDA : ODA = 1 : 1 : 0), the PI-A70-O30-based device (molar feed ratio of DAn : AnDA : ODA = 1 : 0.7 : 0.3) exhibited bipolar resistive switching behavior with stable retention for 104 s. This result implies that the memory properties can be controlled by changing the polyimide composition. The two devices prepared from PI-A100-O0 and PI-A70-O30 showed over 90% transmittance in the visible wavelength range from 400 to 800 nm. The behavior of the memory devices is considered to be governed by trap-controlled, space-charge limited conduction (SCLC) and local filament formation. [Figure not available: see fulltext.

A study of root canal morphology of human primary incisors and molars using cone beam computerized tomography: an in vitro study.

PubMed

Gaurav, Vivek; Srivastava, Nikhil; Rana, Vivek; Adlakha, Vivek Kumar

2013-01-01

Variations in morphology of root canals in primary teeth usually leads to complications during and after endodontic therapy. To improve the success in endodontics, a thorough knowledge of the root canal morphology is essential. The aim of this study was to assess the variation in number and morphology of the root canals of primary incisors and molars and to study the applicability of cone beam computerized tomography (CBCT) in assessing the same. A total of 60 primary molars and incisors with full root length were collected and various parameters such as the number of roots, number of canals, diameter of root canal at cementoenamel junction and middle-third, length and angulations of roots of primary molars and incisors were studied using CBCT. The observations were put to descriptive statistics to find out the frequency, mean, standard deviation and range for all four subgroups. Further, unpaired t-test was used to compare these parameters between subgroups and analysis of variance test was implemented to evaluate the parameters within the subgroups. The CBCT showed the presence of bifurcation of root canal at middle third in 13% of mandibular incisors while 20% of mandibular molars had two canals in distal root. The diameter of distobuccal root canal of maxillary molars and mesiolingual canal of mandibular molars was found to be minimum. CBCT is a relatively new and effective technology, which provides an auxiliary imaging modality to supplement conventional radiography for assessing the variation in root canal morphology of primary teeth.

Determination of Activities of Niobium in Cu-Nb Melts Containing Dilute Nb

NASA Astrophysics Data System (ADS)

Wang, Daya; Yan, Baijun; Sichen, Du

2015-04-01

The activity coefficients of niobium in Cu-Nb melts were measured by equilibrating solid NbO2 with liquid copper under controlled oxygen potentials in the temperature range of 1773 K to 1898 K (1500 °C to 1625 °C). Either CO-CO2 gas mixture or H2-CO2 gas mixture was employed to obtain the desired oxygen partial pressures. Cu-Nb system was found to follow Henry's law in the composition range studied. The temperature dependence of Henry's constant in the Cu-Nb melts could be expressed as follows: The partial molar excess Gibbs energy change of niobium in Cu-Nb melts can be expressed as follows:

QSPR modeling: graph connectivity indices versus line graph connectivity indices

PubMed

Basak; Nikolic; Trinajstic; Amic; Beslo

2000-07-01

Five QSPR models of alkanes were reinvestigated. Properties considered were molecular surface-dependent properties (boiling points and gas chromatographic retention indices) and molecular volume-dependent properties (molar volumes and molar refractions). The vertex- and edge-connectivity indices were used as structural parameters. In each studied case we computed connectivity indices of alkane trees and alkane line graphs and searched for the optimum exponent. Models based on indices with an optimum exponent and on the standard value of the exponent were compared. Thus, for each property we generated six QSPR models (four for alkane trees and two for the corresponding line graphs). In all studied cases QSPR models based on connectivity indices with optimum exponents have better statistical characteristics than the models based on connectivity indices with the standard value of the exponent. The comparison between models based on vertex- and edge-connectivity indices gave in two cases (molar volumes and molar refractions) better models based on edge-connectivity indices and in three cases (boiling points for octanes and nonanes and gas chromatographic retention indices) better models based on vertex-connectivity indices. Thus, it appears that the edge-connectivity index is more appropriate to be used in the structure-molecular volume properties modeling and the vertex-connectivity index in the structure-molecular surface properties modeling. The use of line graphs did not improve the predictive power of the connectivity indices. Only in one case (boiling points of nonanes) a better model was obtained with the use of line graphs.

Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

PubMed

Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

2015-01-01

This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (p<0.001); however, the thickness of ceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (p<0.05). There was no significant difference in fracture resistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

Thermodynamic-ensemble independence of solvation free energy.

PubMed

Chong, Song-Ho; Ham, Sihyun

2015-02-10

Solvation free energy is the fundamental thermodynamic quantity in solution chemistry. Recently, it has been suggested that the partial molar volume correction is necessary to convert the solvation free energy determined in different thermodynamic ensembles. Here, we demonstrate ensemble-independence of the solvation free energy on general thermodynamic grounds. Theoretical estimates of the solvation free energy based on the canonical or grand-canonical ensemble are pertinent to experiments carried out under constant pressure without any conversion.

Activity coefficients from molecular simulations using the OPAS method

NASA Astrophysics Data System (ADS)

Kohns, Maximilian; Horsch, Martin; Hasse, Hans

2017-10-01

A method for determining activity coefficients by molecular dynamics simulations is presented. It is an extension of the OPAS (osmotic pressure for the activity of the solvent) method in previous work for studying the solvent activity in electrolyte solutions. That method is extended here to study activities of all components in mixtures of molecular species. As an example, activity coefficients in liquid mixtures of water and methanol are calculated for 298.15 K and 323.15 K at 1 bar using molecular models from the literature. These dense and strongly interacting mixtures pose a significant challenge to existing methods for determining activity coefficients by molecular simulation. It is shown that the new method yields accurate results for the activity coefficients which are in agreement with results obtained with a thermodynamic integration technique. As the partial molar volumes are needed in the proposed method, the molar excess volume of the system water + methanol is also investigated.

Enhancement of the natural organic matter removal from drinking water by nanofiltration.

PubMed

Matilainen, A; Liikanen, R; Nyström, M; Lindqvist, N; Tuhkanen, T

2004-03-01

Finnish surface waters are abundant in natural organic matter. Natural organic matter can be removed from drinking water in a water treatment process by coagulation and filtration. The standard treatment operations are not able to remove the smallest molar mass fraction of organic matter and the intermediate molar mass matter is only partly removed. The removal of residual natural organic matter from drinking water by nanofiltration was evalueted in this study. Three different nanofiltration membranes were compared in filtering six pre-treated surface waters. The total organic carbon content of the feed waters varied from 2.0 to 4.2 mg l(-1). Other water quality parameters measured were conductivity, alkalinity, hardness, UV-absorbance, SUVA, E2/E3 value and molecular size distribution by high-performance size-exclusion chromatography. The natural organic matter removal efficiencies of the membranes were good and varied between 100% and 49%, and between 85% and 47% according to molecular size distribution and total organic carbon measurements, respectively. Removal of different molecular size fractions varied from 100% to 56%, 100% to 54% and 88% to 19%, regarding high molar mass, intermediate molar mass and low molar mass organic matter, respectively. The Desal-5 DL membrane produced the highest natural organic matter removals.

Western Saudi adolescent age estimation utilising third molar development

PubMed Central

Alshihri, Amin M.; Kruger, Estie; Tennant, Marc

2014-01-01

Objective: The aim of this study was to establish reference data on third molar morphology/development for age estimation in Western Saudi adolescents, between ages 14 and 23 years of old. Materials and Methods: The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. Results: Mean ages, standard deviations, and percentile distributions are presented for each stage of development. The mean estimated age for all participants (n = 130) was 219.7 months, and this differed significantly (P < 0.05) from the mean chronological age (226.5 months). Deviations of predicted age from real age showed 28.5% of all participants had their age estimated within 1 year (±12 months) of their chronological age. Most (43%) had their age underestimated by more than 12 months and the remaining 28.5% had their age overestimated by more than 12 months of their chronological age. Differences in left-right symmetry information of third molars were detected and were higher in the maxilla (92%) than in the mandible (82%). For all molars reaching stage “H” most individuals (males and females) were over the age 18 years of old. Males reach the developmental stages earlier than females. Conclusion: Third molar tooth development can be reliably used to generate mean age and the estimated age range for an individual of unknown chronological age. Further studies with large populations are needed for better statistical results. PMID:25202206

Cone beam volume tomography: an imaging option for diagnosis of complex mandibular third molar anatomical relationships.

PubMed

Danforth, Robert A; Peck, Jerry; Hall, Paul

2003-11-01

Complex impacted third molars present potential treatment complications and possible patient morbidity. Objectives of diagnostic imaging are to facilitate diagnosis, decision making, and enhance treatment outcomes. As cases become more complex, advanced multiplane imaging methods allowing for a 3-D view are more likely to meet these objectives than traditional 2-D radiography. Until recently, advanced imaging options were somewhat limited to standard film tomography or medical CT, but development of cone beam volume tomography (CBVT) multiplane 3-D imaging systems specifically for dental use now provides an alternative imaging option. Two cases were utilized to compare the role of CBVT to these other imaging options and to illustrate how multiplane visualization can assist the pretreatment evaluation and decision-making process for complex impacted mandibular third molar cases.

Age assessment based on third molar mineralisation : An epidemiological-radiological study on a Central-European population.

PubMed

Hofmann, Elisabeth; Robold, Matthias; Proff, Peter; Kirschneck, Christian

2017-03-01

The method published in 1973 by Demirjian et al. to assess age based on the mineralisation stage of permanent teeth is standard practice in forensic and orthodontic diagnostics. From age 14 onwards, however, this method is only applicable to third molars. No current epidemiological data on third molar mineralisation are available for Caucasian Central-Europeans. Thus, a method for assessing age in this population based on third molar mineralisation is presented, taking into account possible topographic and gender-specific differences. The study included 486 Caucasian Central-European orthodontic patients (9-24 years) with unaffected dental development. In an anonymized, randomized, and blinded manner, one orthopantomogram of each patient at either start, mid or end of treatment was visually analysed regarding the mineralisation stage of the third molars according to the method by Demirjian et al. Corresponding topographic and gender-specific point scores were determined and added to form a dental maturity score. Prediction equations for age assessment were derived by linear regression analysis with chronological age and checked for reliability within the study population. Mineralisation of the lower third molars was slower than mineralisation of the upper third molars, whereas no jaw-side-specific differences were detected. Gender-specific differences were relatively small, but girls reached mineralisation stage C earlier than boys, whereas boys showed an accelerated mineralisation between the ages of 15 and 16. The global equation generated by regression analysis (age = -1.103 + 0.268 × dental maturity score 18 + 28 + 38 + 48) is sufficiently accurate and reliable for clinical use. Age assessment only based on either maxilla or mandible also shows good prognostic reliability.

Odontometric sex estimation from clinically extracted molar teeth in a North Indian population sample.

PubMed

Tabasum, Qutsia; Sehrawat, Jagmahender Singh; Talwar, Manjit Kaur; Pathak, Raj Kamal

2017-01-01

Different dental features have contributed significantly toward sex determination in the forensic anthropological contexts. Population-specific standards (discriminant functions or regression formulae) have been suggested for various population groups to identify the sex of an unknown individual from dental dimensions and other odontometric features. The main purpose of the present investigation was to examine the degree of sexual dimorphism exhibited by the human teeth of North Indians and identify importance as a forensic tool in sex determination. The linear and diagonal dimensions were recorded at both crown and cementoenamel junction levels of 58 upper and 72 lower molars of 130 Northwest Indian subjects (73 males and 57 females). The measurements were subjected to appropriate statistical analyses to estimate the sex estimation accuracy from lower and upper molars separately. Univariate analyses revealed that molar teeth had greater dimensions in males than the females and the mesiodistal cervical diameter (MDCV) was found to be the most suitable variable for sex determination of the molars. The classification results were in agreement with the previously conducted studies. The index of sexual dimorphism (ISD) was calculated to be higher in lower molars than the upper molars, and the highest sex differences were observed for MDCV based on the ISD. The overall sex estimation accuracy obtained from multivariate discriminant function analysis and regression analysis of pooled data was 70.0% (74% males, 64.9% females) and 66.9% (78.1% males, 52.6% females), respectively. Odontometrics can play a significant role in establishing the biological identity of an unknown individual even from a single tooth in the absence of other sophisticated molecular or biochemical techniques used for this purpose.

Odontometric sex estimation from clinically extracted molar teeth in a North Indian population sample

PubMed Central

Tabasum, Qutsia; Sehrawat, Jagmahender Singh; Talwar, Manjit Kaur; Pathak, Raj Kamal

2017-01-01

Background: Different dental features have contributed significantly toward sex determination in the forensic anthropological contexts. Population-specific standards (discriminant functions or regression formulae) have been suggested for various population groups to identify the sex of an unknown individual from dental dimensions and other odontometric features. The main purpose of the present investigation was to examine the degree of sexual dimorphism exhibited by the human teeth of North Indians and identify importance as a forensic tool in sex determination. Materials and Methods: The linear and diagonal dimensions were recorded at both crown and cementoenamel junction levels of 58 upper and 72 lower molars of 130 Northwest Indian subjects (73 males and 57 females). The measurements were subjected to appropriate statistical analyses to estimate the sex estimation accuracy from lower and upper molars separately. Results: Univariate analyses revealed that molar teeth had greater dimensions in males than the females and the mesiodistal cervical diameter (MDCV) was found to be the most suitable variable for sex determination of the molars. The classification results were in agreement with the previously conducted studies. The index of sexual dimorphism (ISD) was calculated to be higher in lower molars than the upper molars, and the highest sex differences were observed for MDCV based on the ISD. The overall sex estimation accuracy obtained from multivariate discriminant function analysis and regression analysis of pooled data was 70.0% (74% males, 64.9% females) and 66.9% (78.1% males, 52.6% females), respectively. Conclusions: Odontometrics can play a significant role in establishing the biological identity of an unknown individual even from a single tooth in the absence of other sophisticated molecular or biochemical techniques used for this purpose. PMID:29657498

Impact of flavouring substances on the aggregation behaviour of dissolved barley β-glucans in a model beer.

PubMed

Kupetz, M; Sacher, B; Becker, T

2016-06-05

Structural polymers such as cereal β-glucan may cause various processing problems in beverage industry depending on concentration, molar size distribution and agglomeration behaviour. In this context, influences of the beer volatiles dodecanoic acid, octyl butanoate, ethyl decanoate and decyl acetate on molar mass and radii of barley β-glucan were investigated in ethanolic (4% w/w) model solution. After addition of 100mg/l ethyl decanoate and decyl acetate to the β-glucan solution, a wider-ranging molar mass distribution could be observed by means of asymmetric field-flow-fractionation. Due to agglomeration, average molar mass of β-glucan standard (MW=6.8×10(6)g/mol) increased by 2×10(6)g/mol (P<0.05) in solution containing decyl acetate. Furthermore, a significant growth (P<0.05) from 86 to 102 nm in gyration radius was measured. The obtained results elucidate the importance of fatty acid derived flavouring substance composition in beer regarding the aggregation behaviour of β-glucan. Copyright © 2016 Elsevier Ltd. All rights reserved.

Morphologic analysis of third-molar maturity by digital orthopantomographic assessment.

PubMed

Introna, Francesco; Santoro, Valeria; De Donno, Antonio; Belviso, Maura

2008-03-01

Accurate timing of the eruption of first and permanent teeth is an important parameter in forensic odontology to establish the age of dead or live individuals. Determination of adulthood may determine, for example, whether an individual convicted of a crime is sentenced as an adult and incarcerated in a state penal institution or as a juvenile and sent to a juvenile camp. At present, there is a large immigrant population in Italy, and young foreign criminals sometimes have false passports bearing a later birth date, with the aim of evading punishment. In such circumstances, age determination is becoming a significant forensic issue.Late in adolescence, after formation of the premolars and canines, only the third molars continue to develop. According to several studies, although the third molars are the most variable teeth in the dentition, they remain the most reliable biologic indicator available for estimation of age during the middle teens and early twenties.In this study, the authors test the possibilities offered by orthopantomography executed by means of digital technology, with the aim of exploiting the advantages of the computerized digital technique compared with the conventional technique, to determine adult age on the basis of root development of the third molar.Digital radiography is simple to use, quick, and effective, allowing superimposition and enlargement; the images can be electronically stored and transported. In comparison with traditional orthopantomography, the digital technique features greater diagnostic accuracy of some anatomic structures: upper and lower front teeth, root apexes, floor of the nasal fossa and maxillary sinus, nasal septum, mandibular condylus. Moreover, digital orthopantomography suffers less from artifacts.The digital orthopantomographies of 83 Caucasian subjects (43 females and 40 males) aged between 16 and 22 years were analyzed in standard conditions, assessing the degree of maturation of the upper and lower third molars. A standardized computer procedure was used to acquire the x-ray images, recording 3 per plate: the overall orthopantomography and 2 enlargements of optical type of the left and right sides, to reveal the third molars while maintaining unaltered the image resolution.For the analysis, the authors adopted Demirjian's staging system that classifies development of the third molar in 8 stages (A, B, C, D, E, F, G, H) on the basis of morphologic criteria. This has been statistically proved to feature notable precision and high predictive ability.To assess any sex-related variations in mineralization speed, the series was subdivided by gender. The study demonstrated that such differences are more evident under the age of 18 years.Overall, the observation of 245 third molars showed faster development of the upper than the lower third molars, a prevalence of stages D to G in the age range between 16 and 18 years, and a clear predominance of stage H in individuals over 18 years of age. Finally, an intermediate stage between G and H was demonstrated in subjects aged between 17 and 21 years.

A study of the kinetics of the reduction of neptunium(VI) by acetohydroxamic acid in perchloric acid

NASA Astrophysics Data System (ADS)

Matteson, Brent S.; Precek, Martin; Paulenova, Alena

2010-03-01

The kinetics of reduction of NpO22+ to NpO2+ by acetohydroxamic acid in 1 mol·L-1perchloric acid media at 10 and 22°C were studied. The reaction rate was monitored using stopped-flow and standard infrared spectroscopy. Under conditions such that acetohydroxamic acid was in excess relative to Np, the reduction rate of NpO22+ is described by the following: where k = 2.57x103 mol-1·L·sec-1 at 10°C. However, when neptunium is in a significant molar excess relative to acetohydroxamic acid, the reduction mechanism is dictated by two distinct reactions. An initial and incomplete reduction occurs as the result of the oxidation of AHA, while a slower and partial reduction of NpO22+ is likely caused by the oxidation products of AHA. The reaction rate of this first-order mechanism was calculated as 3.7x10-4 sec-1 at 10°C and 0.001 sec-1 at 22°C.

Fragile X syndrome: panoramic radiographic evaluation of dental anomalies, dental mineralization stage, and mandibular angle.

PubMed

Sabbagh-Haddad, Aida; Haddad, Denise Sabbagh; Michel-Crosato, Edgard; Arita, Emiko Saito

2016-01-01

The purpose of this study was to evaluate the dental radiographic characteristics as described in 40 records of patients with panoramic radiography. The patients were in the range of 6-17 years old, and were divided into two groups (20 subjects who were compatible with the normality standard and 20 individuals diagnosed with the FXS), which were matched for gender and age. Analysis of the panoramic radiographic examination involved the evaluation of dental mineralization stage, mandibular angle size, and presence of dental anomalies in both deciduous and permanent dentitions. The results of radiographic evaluation demonstrated that the chronology of tooth eruption of all third and second lower molars is anticipated in individuals with FXS (p<0.05). In this group, supernumerary deciduous teeth (2.83%), giroversion of permanent teeth (2.31%), and partial anodontia (1.82%) were the most frequent dental anomalies. In addition, an increase was observed in the mandibular angle size in the FXS group (p<0.05). We conclude that knowledge of dental radiographic changes is of great importance for dental surgeons to plan the treatment of these individuals.

Standard Gibbs energy of formation of Mo 3Te 4 by emf measurements

NASA Astrophysics Data System (ADS)

Mallika, C.; Sreedharan, O. M.

1990-03-01

The emf of the galvanic cells Pt, Mo, MoO 2¦8 YSZ¦'FeO', Fe, Pt (I) and Pt, Fe,'FeO' ¦8 YSZ¦MoO 2, Mo 3Te 4, MoTe 2(α), C, Pt (II) were measured over the temperature ranges 837 to 1151 K and 775 to 1196 K, respectively, using 8 mass% yttria-stabilized zirconia (8 YSZ) as the solid electrolyte. From the emf values, the partial molar Gibbs energy of solution of molybdenum in Mo 3Te 4/MoTe 2(α), Δ ḠMo was found to be Δ ḠMo ± 1.19 ( kJ/mol) = -025.08 + 0.00420T(K) . Using the literature data for the Gibbs energy of formation of MoTe 2(α). the expression ΔG° f( Mo3Te4, s) ± 5.97 (kj/mol) = -253.58 + 0.09214 T( K) was derived for the range 775 to 1196 K. A third-law analysis yielded a value of -209 ± 10 kJ/mol for ΔH° f.298o of Mo 3Te 4(s).

Critical properties and high-pressure volumetric behavior of the carbon dioxide+propane system at T=308.15 k. Krichevskii function and related thermodynamic properties.

PubMed

Blanco, Sofía T; Gil, Laura; García-Giménez, Pilar; Artal, Manuela; Otín, Santos; Velasco, Inmaculada

2009-05-21

Critical properties and volumetric behavior for the {CO2(1)+C3H8(2)} system have been studied. The critical locus was measured with a flow apparatus and detected by critical opalescence. For the mixtures, repeatabilities in critical temperature and pressure are rTc

Associations between Carabelli trait and cusp areas in human permanent maxillary first molars.

PubMed

Kondo, Shintaro; Townsend, Grant C

2006-02-01

Few dental anthropological studies have investigated the associations between tooth crown size and crown traits in humans using quantitative methods. We tested several hypotheses about overall crown size, individual cusp areas, and expression of Carabelli cusps in human permanent first molars by obtaining data from standardized occlusal photographs of 308 Australians of European descent (171 males and 137 females). Specifically, we aimed to calculate the areas of the four main molar cusps, and also Carabelli cusp, and to compare the relative variability of cusp areas in relation to timing of development. We also aimed to compare cusp areas between males and females and to describe how Carabelli cusp interacted with other molar cusps. Measurements included maximum crown diameters (mesiodistal and buccolingual crown diameters), the areas of the four main cusps, and the area of Carabelli cusp. The pattern of relative variability in absolute areas of molar cusps corresponded with their order of formation, the first-forming paracone displaying the least variation, and the last-forming Carabelli cusp showing the greatest. Overall crown size and areas of individual cusps all showed sexual dimorphism, with values in males exceeding those in females. Sexual dimorphism was smallest for paracone area and greatest for Carabelli cusp area. Overall crown size and cusp areas were larger in individuals displaying a Carabelli cusp, especially the hypocone area. Although the combined area of the protocone and a Carabelli cusp was greater in cuspal forms than noncuspal forms, protocone area alone was significantly smaller in the former. Our findings lead us to propose that, in individuals with the genotype for Carabelli trait expression, larger molar crowns are more likely to display Carabelli cusps, whereas molars with smaller crowns are more likely to display reduced forms of expression of the trait. We suggest that the pattern of folding of the internal enamel epithelium in developing molar crowns, particularly in the protocone region, can be modified by a developing Carabelli cusp.

Partial purification and characterization of a Ca(2+)-dependent protein kinase from the green alga, Dunaliella salina

NASA Technical Reports Server (NTRS)

Roux, S. J.

1990-01-01

A calcium-dependent protein kinase was partially purified and characterized from the green alga Dunaliella salina. The enzyme was activated at free Ca2+ concentrations above 10(-7) molar. and half-maximal activation was at about 3 x 10(-7) molar. The optimum pH for its Ca(2+)-dependent activity was 7.5. The addition of various phospholipids and diolein had no effects on enzyme activity and did not alter the sensitivity of the enzyme toward Ca2+. The enzyme was inhibited by calmodulin antagonists, N-(6-aminohexyl)-1-naphthalene sulfonamide and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide in a dose-dependent manner while the protein kinase C inhibitor, sphingosine, had little effect on enzyme activity up to 800 micromolar. Immunoassay showed some calmodulin was present in the kinase preparations. However, it is unlikely the kinase was calmodulin regulated, since it still showed stimulation by Ca2+ in gel assays after being electrophoretically separated from calmodulin by two different methods. This gel method of detection of the enzyme indicated that a protein band with an apparent molecular weight of 40,000 showed protein kinase activity at each one of the several steps in the purification procedure. Gel assay analysis also showed that after native gel isoelectric focusing the partially purified kinase preparations had two bands with calcium-dependent activity, at isoelectric points 6.7 and 7.1. By molecular weight, by isoelectric point, and by a comparative immunoassay, the Dunaliella kinase appears to differ from at least some of the calcium-dependent, but calmodulin and phospholipid independent kinases described from higher plants.

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

PubMed

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

2015-08-01

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. 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. 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. 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.

Effects of fiber-glass-reinforced composite restorations on fracture resistance and failure mode of endodontically treated molars.

PubMed

Nicola, Scotti; Alberto, Forniglia; Riccardo, Michelotto Tempesta; Allegra, Comba; Massimo, Saratti Carlo; Damiano, Pasqualini; Mario, Alovisi; Elio, Berutti

2016-10-01

The study evaluated the fracture resistance and fracture patterns of endodontically treated mandibular first molars restored with glass-fiber-reinforced direct composite restorations. In total, 60 extracted intact first molars were treated endodontically; a mesio-occluso-distal (MOD) cavity was prepared and specimens were then divided into six groups: sound teeth (G1), no restoration (G2), direct composite restoration (G3), fiber-post-supported direct composite restoration (G4), direct composite reinforced with horizontal mesio-distal glass-fibers (G5), and buccal-palatal glass-fibers (G6). Specimens were subjected to 5000 thermocycles and 20,000 cycles of 45° oblique loading force at 1.3Hz and 50N; they were then loaded until fracture. The maximum fracture loads were recorded in Newtons (N) and data were analyzed with one-way ANOVA and post-hoc Tukey tests (p<0.05). Fractured specimens were analyzed with a scanning electron microscope (SEM). The mean static loads (in Newtons) were: G1, 831.83; G2, 282.86; G3, 364.18; G4, 502.93; G5, 499.26; and G6, 582.22. Fracture resistance did not differ among G4, G5, and G6, but was significantly higher than G3 (p=0.001). All specimens fractured in a catastrophic way. In G6, glass fibers inducted a partial deflection of the fracture, although they were not able to stop crack propagation. For the direct restoration of endodontically treated molars, reinforcement of composite resins with glass-fibers or fiber posts can enhance fracture resistance. The SEM analysis showed a low ability of horizontal glass-fibers to deviate the fracture, but this effect was not sufficient to lead to more favorable fracture patterns above the cement-enamel junction (CEJ). The fracture resistance of endodontically treated molars restored with direct composite restorations seems to be increased by reinforcement with fibers, even if it is insufficient to restore sound molar fracture resistance and cannot avoid vertical fractures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of scan mode (180°/360°) of the cone beam computed tomography for preoperative dental implant measurements.

PubMed

Neves, Frederico S; Vasconcelos, Taruska V; Campos, Paulo S F; Haiter-Neto, Francisco; Freitas, Deborah Q

2014-02-01

The aim of this study was to evaluate the effect of scan mode of the cone beam computed tomography (CBCT) in the preoperative dental implant measurements. Completely edentulous mandibles with entirely resorbed alveolar processes were selected for this study. Five regions were selected (incisor, canine, premolar, first molar, and second molar). The mandibles were scanned with Next Generation i-CAT CBCT unit (Imaging Sciences International, Inc, Hatfield, PA, USA) with half (180°) and full (360°) mode. Two oral radiologists performed vertical measurements in all selected regions; the measurements of half of the sample were repeated within an interval of 30 days. The mandibles were sectioned using an electrical saw in all evaluated regions to obtain the gold standard. The intraclass correlation coefficient was calculated for the intra- and interobserver agreement. Descriptive statistics were calculated as mean, median, and standard deviation. Wilcoxon signed rank test was used to determine the correlation between the measurements obtained in different scan mode with the gold standard. The significance level was 5%. The values of intra- and interobserver reproducibility indicated a strong agreement. In the dental implant measurements, except the bone height of the second molar region in full scan mode (P = 0.02), the Wilcoxon signed rank test did not show statistical significant difference with the gold standard (P > 0.05). Both modes provided real measures, necessary when performing implant planning; however, half scan mode uses smaller doses, following the principle of effectiveness. We believe that this method should be used because of the best dose-effect relationship and offer less risk to the patient. © 2012 John Wiley & Sons A/S.

Unfolding and refolding details of lysozyme in the presence of β-casein micelles.

PubMed

Wu, Fu-Gen; Luo, Jun-Jie; Yu, Zhi-Wu

2011-02-28

In this work, we selected a small globular protein, lysozyme, to study how it unfolds and refolds in the presence of micelles composed of the unstructured β-casein proteins by using microcalorimetry and circular dichroism spectroscopy. It was found that a partially unfolded structure of lysozyme starts to form when the β-casein/lysozyme molar ratio is above 0.7, and the structure forms exclusively when the β-casein/lysozyme molar ratio is above 1.6. This partially unfolded state of lysozyme loses most of its tertiary structure and after heating, the denatured lysozyme molecules are trapped in the charged coatings of β-casein micelles and cannot refold upon cooling. The thus obtained protein complex can be viewed as a kind of special polyelectrolyte complex micelle. The net charge ratios of the two proteins and the ionic strength of the dispersions can significantly modulate the electrostatic and hydrophobic interactions between the two proteins. Our present work may have implications for the nanoparticle protein engineering therapy in the biomedicine field and may provide a better understanding of the principles governing the protein-protein interactions. Besides, the heating-cooling-reheating procedure employed in this work can also be used to study the unfolding and refolding details of the target protein in other protein-protein, protein-polymer and protein-small solute systems.

Tooth loss in well-maintained patients with chronic periodontitis during long-term supportive therapy in Brazil.

PubMed

Chambrone, Luiz A; Chambrone, Leandro

2006-10-01

The objective of this retrospective study was to assess the reasons for tooth loss in a sample of patients who underwent periodontal therapy and supportive periodontal therapy (SPT) in a Brazilian private periodontal practice. A sample of 120 subjects who had been treated and maintained for 10 years or longer was selected from patients attending a periodontal practice. All patients followed a similar treatment: basic procedures, re-evaluation and periodontal surgery where indicated. Reasons for tooth loss were categorized as periodontal, caries, endodontal, root fractures and extraction of retained or partially erupted third molars. Of the 2927 teeth present at the completion of active periodontal treatment, 53 (1.8%) were lost due to periodontal disease, 16 (0.5%) for root fracture, six (0.2%) to caries, five (0.2%) for endodontic reasons and 31 (1.0%) were lost to extraction of retained or partially erupted third molars. Logistic regression analysis was performed to investigate the association between five independent variables with tooth loss due to periodontitis. Only age (> 60 years) and smoking were statistically significant (p < 0.05). The findings of this survey were consistent with previous studies. Older subjects and smokers were more susceptible to periodontal tooth loss. In addition, patients with generalized chronic periodontitis were treated and maintained for long-term periods with low rates of tooth loss.

Heterogeneous uptake of ammonia and dimethylamine into sulfuric and oxalic acid particles

NASA Astrophysics Data System (ADS)

Sauerwein, Meike; Keung Chan, Chak

2017-05-01

Heterogeneous uptake is one of the major mechanisms governing the amounts of short-chain alkylamines and ammonia (NH3) in atmospheric particles. Molar ratios of aminium to ammonium ions detected in ambient aerosols often exceed typical gas phase ratios. The present study investigated the simultaneous uptake of dimethylamine (DMA) and NH3 into sulfuric and oxalic acid particles at gaseous DMA / NH3 molar ratios of 0.1 and 0.5 at 10, 50 and 70 % relative humidity (RH). Single-gas uptake and co-uptake were conducted under identical conditions and compared. Results show that the particulate dimethyl-aminium/ammonium molar ratios (DMAH / NH4) changed substantially during the uptake process, which was severely influenced by the extent of neutralisation and the particle phase state. In general, DMA uptake and NH3 uptake into concentrated H2SO4 droplets were initially similarly efficient, yielding DMAH / NH4 ratios that were similar to DMA / NH3 ratios. As the co-uptake continued, the DMAH / NH4 gradually dropped due to a preferential uptake of NH3 into partially neutralised acidic droplets. At 50 % RH, once the sulfate droplets were neutralised, the stronger base DMA displaced some of the ammonium absorbed earlier, leading to DMAH / NH4 ratios up to four times higher than the corresponding gas phase ratios. However, at 10 % RH, crystallisation of partially neutralised sulfate particles prevented further DMA uptake, while NH3 uptake continued and displaced DMAH+, forming almost pure ammonium sulfate. Displacement of DMAH+ by NH3 has also been observed in neutralised, solid oxalate particles. The results can explain why DMAH / NH4 ratios in ambient liquid aerosols can be larger than DMA / NH3, despite an excess of NH3 in the gas phase. An uptake of DMA to aerosols consisting of crystalline ammonium salts, however, is unlikely, even at comparable DMA and NH3 gas phase concentrations.

Design and Initial Characterization of the SC-200 Proteomics Standard Mixture

PubMed Central

Bauman, Andrew; Higdon, Roger; Rapson, Sean; Loiue, Brenton; Hogan, Jason; Stacy, Robin; Napuli, Alberto; Guo, Wenjin; van Voorhis, Wesley; Roach, Jared; Lu, Vincent; Landorf, Elizabeth; Stewart, Elizabeth; Kolker, Natali; Collart, Frank; Myler, Peter; van Belle, Gerald

2011-01-01

Abstract High-throughput (HTP) proteomics studies generate large amounts of data. Interpretation of these data requires effective approaches to distinguish noise from biological signal, particularly as instrument and computational capacity increase and studies become more complex. Resolving this issue requires validated and reproducible methods and models, which in turn requires complex experimental and computational standards. The absence of appropriate standards and data sets for validating experimental and computational workflows hinders the development of HTP proteomics methods. Most protein standards are simple mixtures of proteins or peptides, or undercharacterized reference standards in which the identity and concentration of the constituent proteins is unknown. The Seattle Children's 200 (SC-200) proposed proteomics standard mixture is the next step toward developing realistic, fully characterized HTP proteomics standards. The SC-200 exhibits a unique modular design to extend its functionality, and consists of 200 proteins of known identities and molar concentrations from 6 microbial genomes, distributed into 10 molar concentration tiers spanning a 1,000-fold range. We describe the SC-200's design, potential uses, and initial characterization. We identified 84% of SC-200 proteins with an LTQ-Orbitrap and 65% with an LTQ-Velos (false discovery rate = 1% for both). There were obvious trends in success rate, sequence coverage, and spectral counts with protein concentration; however, protein identification, sequence coverage, and spectral counts vary greatly within concentration levels. PMID:21250827

Design and initial characterization of the SC-200 proteomics standard mixture.

PubMed

Bauman, Andrew; Higdon, Roger; Rapson, Sean; Loiue, Brenton; Hogan, Jason; Stacy, Robin; Napuli, Alberto; Guo, Wenjin; van Voorhis, Wesley; Roach, Jared; Lu, Vincent; Landorf, Elizabeth; Stewart, Elizabeth; Kolker, Natali; Collart, Frank; Myler, Peter; van Belle, Gerald; Kolker, Eugene

2011-01-01

High-throughput (HTP) proteomics studies generate large amounts of data. Interpretation of these data requires effective approaches to distinguish noise from biological signal, particularly as instrument and computational capacity increase and studies become more complex. Resolving this issue requires validated and reproducible methods and models, which in turn requires complex experimental and computational standards. The absence of appropriate standards and data sets for validating experimental and computational workflows hinders the development of HTP proteomics methods. Most protein standards are simple mixtures of proteins or peptides, or undercharacterized reference standards in which the identity and concentration of the constituent proteins is unknown. The Seattle Children's 200 (SC-200) proposed proteomics standard mixture is the next step toward developing realistic, fully characterized HTP proteomics standards. The SC-200 exhibits a unique modular design to extend its functionality, and consists of 200 proteins of known identities and molar concentrations from 6 microbial genomes, distributed into 10 molar concentration tiers spanning a 1,000-fold range. We describe the SC-200's design, potential uses, and initial characterization. We identified 84% of SC-200 proteins with an LTQ-Orbitrap and 65% with an LTQ-Velos (false discovery rate = 1% for both). There were obvious trends in success rate, sequence coverage, and spectral counts with protein concentration; however, protein identification, sequence coverage, and spectral counts vary greatly within concentration levels.

Determination of the molar mass of argon from high-precision acoustic comparisons.

PubMed

Feng, X J; Zhang, J T; Moldover, M R; Yang, I; Plimmer, M D; Lin, H

2017-06-01

This article describes the accurate determination of the molar mass M of a sample of argon gas used for the determination of the Boltzmann constant. The method of one of the authors (Moldover et al 1988 J. Res. Natl. Bur. Stand. 93 85-144) uses the ratio of the square speed of sound in the gas under analysis and in a reference sample of known molar mass. A sample of argon that was isotopically-enriched in 40 Ar was used as the reference, whose unreactive impurities had been independently measured. The results for three gas samples are in good agreement with determinations by gravimetric mass spectrometry; (〈 M acoustic / M mass-spec 〉 - 1) = (-0.31 ± 0.69) × 10 -6 , where the indicated uncertainty is one standard deviation that does not account for the uncertainties from the acoustic and mass-spectroscopy references.

Determination of the molar mass of argon from high-precision acoustic comparisons

PubMed Central

Feng, X J; Zhang, J T; Moldover, M R; Yang, I; Plimmer, M D; Lin, H

2017-01-01

This article describes the accurate determination of the molar mass M of a sample of argon gas used for the determination of the Boltzmann constant. The method of one of the authors (Moldover et al 1988 J. Res. Natl. Bur. Stand. 93 85–144) uses the ratio of the square speed of sound in the gas under analysis and in a reference sample of known molar mass. A sample of argon that was isotopically-enriched in 40Ar was used as the reference, whose unreactive impurities had been independently measured. The results for three gas samples are in good agreement with determinations by gravimetric mass spectrometry; (〈Macoustic/Mmass-spec〉 − 1) = (−0.31 ± 0.69) × 10−6, where the indicated uncertainty is one standard deviation that does not account for the uncertainties from the acoustic and mass-spectroscopy references. PMID:29332953

Evaluation of the relationship between mandibular third molar and mandibular canal by different algorithms of cone-beam computed tomography.

PubMed

Mehdizadeh, Mojdeh; Ahmadi, Navid; Jamshidi, Mahsa

2014-11-01

Exact location of the inferior alveolar nerve (IAN) bundle is very important. The aim of this study is to evaluate the relationship between the mandibular third molar and the mandibular canal by cone-beam computed tomography. This was a cross-sectional study with convenience sampling. 94 mandibular CBCTs performed with CSANEX 3D machine (Soredex, Finland) and 3D system chosen. Vertical and horizontal relationship between the mandibular canal and the third molar depicted by 3D, panoramic reformat view of CBCT and cross-sectional view. Cross-sectional view was our gold standard and other view evaluated by it. There were significant differences between the vertical and horizontal relation of nerve and tooth in all views (p < 0.001). The results showed differences in the position of the inferior alveolar nerve with different views of CBCT, so CBCT images are not quite reliable and have possibility of error.

[Consequences of impacted wisdom teeth extraction on the periodontal environment of second molars. A pilot study].

PubMed

Martin, R; Louvrier, A; Weber, E; Chatelain, B; Meyer, C

2017-04-01

Wisdom teeth extraction is a common procedure, generally considered as safe by patients. However, complications are possible, especially periodontal ones. The aim of this study was to evaluate the frequency and the consequences of periodontal complications at the level the 2nd molars after extraction of the wisdom teeth. A single-center retrospective observational multi-operator study was conducted at the university hospital of Besançon - France. The files of all the adult patients who underwent extraction of four impacted wisdom teeth by mean of a standardized surgical technique between November 2012 and November 2014 and who could be followed 1 year postoperatively at least and that precisely mentioned the periodontal status of the surgical sites were included. Postoperative complications, gingival and plaque indexes according to Loë and Silness, periodontal attachment level and periodontal second molar probing were recorded. The main judgment criterion was the occurrence of a periodontal complication in the second molar areas. The files of 20 patients (15 women - 5 men), operated on by five different surgeons, met the inclusion criteria. Two patients suffered from dry socket at one of the avulsion sites. No patient had a gingival or plaque index greater than 2. No gingival recession or periodontal pocket over 4mm was found. Extraction of impacted third molars in young healthy adults didn't have any impact on the second molars periodontal environment in our study. Literature suggests that surgical technique greatly influences the occurrence and the extent of periodontal sequelae. Copyright © 2017. Published by Elsevier Masson SAS.

Oxygen stoichiometry, phase stability, and thermodynamic behavior of the lead-doped Bi-2223 and Ag/Bi-2223 systems

NASA Astrophysics Data System (ADS)

Tetenbaum, M.; Hash, M.; Tani, B. S.; Luo, J. S.; Maroni, V. A.

1995-02-01

Electromotive-force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made in the lead-doped Bi-2223 superconducting system in the temperature range 700-815°C by means of an oxygen titration technique that employs an yttria-stabilized zirconia electrolyte. The results of our studies indicate that processing or annealing lead-doped Bi-2223 at temperatures ranging from 750 to 815°C and at oxygen partial pressures ranging from ∼ 0.02 to 0.2 atm should preserve Bi-2223 as essentially single-phase material. Thermodynamic assessments of the partial molar quantities ΔS¯( O2) andΔH¯( O2) indicate that the plateau regions in the plot of oxygen partial pressure versus oxygen stoichiometry ( x) can be represented by the diphasic CuOCu 2O system. In accord with the EMF measurements, it was found that lead-doped Bi-2223 in a silver sheath is stable at 815°C for oxygen partial pressures between 0.02 and 0.13 atm.

Thermodynamic and nonstoichiometric behavior of the lead-doped Bi-2223 system

NASA Astrophysics Data System (ADS)

Tetenbaum, M.; Hash, M.; Tani, B. S.; Luo, J. S.; Maroni, V. A.

1994-12-01

Electromotive force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made in the lead-doped Bi-2223 superconducting system in the temperature range 700-815°C by means of an oxygen titration technique. The results of our studies indicate that processing or annealing lead-doped Bi-2223 at temperatures ranging from 700 to 815°C and at oxygen partial pressures ranging from ∼0.02 to 0.2 atm should tend to preserve Bi-2223 as essentially single-phase material. Thermodynamic assessments of partial molar quantities indicate that the plateau regions can be represented by the diphasic CuOCu 2O system. In accord with the EMF measurements, it was found that lead-doped Bi-2223 in a silver sheath is stable at 815°C for oxygen partial pressures between 0.02 and 0.13 atm. Long-duration post anneals of silver-clad Bi-2223 filaments at 825°C and an oxygen partial pressure of 0.075 atm eliminated Bi-2212 intergrowths with a concomitant increase in the superconducting transition sharpness.

Solubility of carbon dioxide in aqueous mixtures of alkanolamines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dawodu, O.F.; Meisen, A.

1994-07-01

The solubility of CO[sub 2] in water + N-methyldiethanolamine + monoethanolamine (MDEA + MEA) and water + N-methyldiethanolamine + diethanolamine (MDEA + DEA) are reported at two compositions of 3.4 M MDEA + 0.8 M MEA or DEA and 2.1 M MDEA + 2.1 M MEA or DEA at temperatures from 70 to 180 C and CO[sub 2] partial pressures from 100 to 3,850 kPa. The solubility of CO[sub 2] in the blends decreased with an increase in temperature but increased with an increase in CO[sub 2] partial pressure. At low partial pressures of CO[sub 2] and the same totalmore » amine concentration, the equilibrium CO[sub 2] loadings were in the order MDEA + MEA > MDEA + DEA > MDEA. However, at high CO[sub 2] partial pressures, the equilibrium CO[sub 2] loadings in the MDEA solutions were higher than those of the MDEA + MEA and MDEA + DEA blends of equal molar strengths due to the stoichiometric loading limitations of MEA and DEA. The nonadditivity of the equilibrium loadings for single amine systems highlights the need for independent measurements on amine blends.« less

Solvation thermodynamics of L-cystine, L-tyrosine, and L-leucine in aqueous-electrolyte media

NASA Astrophysics Data System (ADS)

Roy, Sanjay; Guin, Partha Sarathi; Mahali, Kalachand; Dolui, Bijoy Krishna

2017-12-01

Solubilities of L-cystine, L-tyrosine, and L-leucine in aqueous NaCl media at 298.15 K have been studied. Indispensable and related solvent parameters such as molar mass, molar volume, etc., were also determined. The results are used to evaluate the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy and dipole-dipole interaction effects during the course of solvation. Various weak interactions involving solute-solvent or solvent-solvent molecules were characterized in order to find their role on the solvation of these amino acids.

The Produce of Methyl Ester from Crude Palm Oil (CPO) Using Heterogene Catalyst Ash of Chicken Bone (CaO) using Ethanol as Solvent

NASA Astrophysics Data System (ADS)

Sinaga, M. S.; Fauzi, R.; Turnip, J. R.

2017-03-01

Methyl Ester (methyl ester) is generally made by trans esterification using heterogeneous base catalyst. To simplify the separation, the heterogeneous catalyst is used, such as CaO, which in this case was isolated from chicken bones made by softening chicken bones and do calcination process. Some other important variables other than the selection of the catalyst is the catalyst dosage, molar ratio of ethanol to the CPO and the reaction temperature. The best result from this observe is at the molar ratio of ethanol to the CPO is 17: 1, the reaction temperature is 70 ° C and 7% catalyst (w.t) with reaction time for 7 hours at 500 rpm as a constant variable, got 90,052 % purity, so that this result does not get the standard requirements of biodiesel, because of the purity of the biodiesel standard temporary must be achieve > 96.5 %. This study aims to produce methyl ester yield with the influence of the reaction temperature, percent of catalyst and molar ratio of ethanol and CPO. The most influential variable is the temperature of the reaction that gives a significant yield difference of methyl ester produced. It’s been proven by the increasing temperature used will also significantly increase the yield of methyl ester.

Size exclusion chromatography-gradients, an alternative approach to polymer gradient chromatography: 2. Separation of poly(meth)acrylates using a size exclusion chromatography-solvent/non-solvent gradient.

PubMed

Schollenberger, Martin; Radke, Wolfgang

2011-10-28

A gradient ranging from methanol to tetrahydrofuran (THF) was applied to a series of poly(methyl methacrylate) (PMMA) standards, using the recently developed concept of SEC-gradients. Contrasting to conventional gradients the samples eluted before the solvent, i.e. within the elution range typical for separations by SEC, however, the high molar mass PMMAs were retarded as compared to experiments on the same column using pure THF as the eluent. The molar mass dependence on retention volume showed a complex behaviour with a nearly molar mass independent elution for high molar masses. This molar mass dependence was explained in terms of solubility and size exclusion effects. The solubility based SEC-gradient was proven to be useful to separate PMMA and poly(n-butyl crylate) (PnBuA) from a poly(t-butyl crylate) (PtBuA) sample. These samples could be separated neither by SEC in THF, due to their very similar hydrodynamic volumes, nor by an SEC-gradient at adsorbing conditions, due to a too low selectivity. The example shows that SEC-gradients can be applied not only in adsorption/desorption mode, but also in precipitation/dissolution mode without risking blocking capillaries or breakthrough peaks. Thus, the new approach is a valuable alternative to conventional gradient chromatography. Copyright © 2011 Elsevier B.V. All rights reserved.

Age estimation using the radiographic visibility of the periodontal ligament in lower third molars in a Portuguese population.

PubMed

Sequeira, Catarina-Dourado; Teixeira, Alexandra; Caldas, Inês-Morais; Afonso, Américo; Pérez-Mongiovi, Daniel

2014-12-01

The mineralization of third molars has been used repeatedly as a method of forensic age estimation. However, this procedure is of little use beyond age 18, especially to determinate if an individual is older than 21 years of age; thus, the development of new approaches is essential. The visibility of the periodontal ligament has been suggested for this purpose. The aim of this work was to determine the usefulness of this methodology in a Portuguese population. Periodontal ligament visibility was assessed in the lower third molars, using a sample of 487 orthopantomograms, 228 of which belonging to females and 259 to males, from a Portuguese population aged 17 to 31 years. A classification of four stages based on the visual phenomenon of disappearance of the periodontal ligament of fully mineralized third molars was used. For each stage, median, variance, minimal and maximal age were assessed. The relationship between age and stage of periodontal ligament had a statistical significance for both sexes. In this population, stage 3 can be used to state that a male person is over 21 years-old; for females, another marker should be used. This technique can be useful for determining age over 21, particularly in males. Differences between studies are evident, suggesting that specific population standards should be used when applying this technique. Key words:Forensic sciences, forensic odontology, age estimation, third molar, periodontal ligament.

Thermal and volumetric properties of complex aqueous electrolyte solutions using the Pitzer formalism - The PhreeSCALE code

NASA Astrophysics Data System (ADS)

Lach, Adeline; Boulahya, Faïza; André, Laurent; Lassin, Arnault; Azaroual, Mohamed; Serin, Jean-Paul; Cézac, Pierre

2016-07-01

The thermal and volumetric properties of complex aqueous solutions are described according to the Pitzer equation, explicitly taking into account the speciation in the aqueous solutions. The thermal properties are the apparent relative molar enthalpy (Lϕ) and the apparent molar heat capacity (Cp,ϕ). The volumetric property is the apparent molar volume (Vϕ). Equations describing these properties are obtained from the temperature or pressure derivatives of the excess Gibbs energy and make it possible to calculate the dilution enthalpy (∆HD), the heat capacity (cp) and the density (ρ) of aqueous solutions up to high concentrations. Their implementation in PHREEQC V.3 (Parkhurst and Appelo, 2013) is described and has led to a new numerical tool, called PhreeSCALE. It was tested first, using a set of parameters (specific interaction parameters and standard properties) from the literature for two binary systems (Na2SO4-H2O and MgSO4-H2O), for the quaternary K-Na-Cl-SO4 system (heat capacity only) and for the Na-K-Ca-Mg-Cl-SO4-HCO3 system (density only). The results obtained with PhreeSCALE are in agreement with the literature data when the same standard solution heat capacity (Cp0) and volume (V0) values are used. For further applications of this improved computation tool, these standard solution properties were calculated independently, using the Helgeson-Kirkham-Flowers (HKF) equations. By using this kind of approach, most of the Pitzer interaction parameters coming from literature become obsolete since they are not coherent with the standard properties calculated according to the HKF formalism. Consequently a new set of interaction parameters must be determined. This approach was successfully applied to the Na2SO4-H2O and MgSO4-H2O binary systems, providing a new set of optimized interaction parameters, consistent with the standard solution properties derived from the HKF equations.

Low-temperature heat capacity and entropy of chalcopyrite (CuFeS2): estimates of the standard molar enthalpy and Gibbs free energy of formation of chalcopyrite and bornite (Cu5FeS4)

USGS Publications Warehouse

Robie, R.A.; Wiggins, L.B.; Barton, P.B.; Hemingway, B.S.

1985-01-01

The heat capacity of CuFeS2 (chalcopyrite) was measured between 6.3 and 303.5 K. At 298.15 K, Cp,mo and Smo(T) are (95.67??0.14) J??K-1??mol-1 and (124.9??0.2) J??K-1??mol-1, respectively. From a consideration of the results of two sets of equilibrium measurements we conclude that ??fHmo(CuFeS2, cr, 298.15 K) = -(193.6??1.6) kJ??mol-1 and that the recent bomb-calorimetric determination by Johnson and Steele (J. Chem. Thermodynamics 1981, 13, 991) is in error. The standard molar Gibbs free energy of formation of bornite (Cu5FeS4) is -(444.9??2.1) kJ??mol-1 at 748 K. ?? 1985.

Last Glacial Maximum Salinity Reconstruction

NASA Astrophysics Data System (ADS)

Homola, K.; Spivack, A. J.

2016-12-01

It has been previously demonstrated that salinity can be reconstructed from sediment porewater. The goal of our study is to reconstruct high precision salinity during the Last Glacial Maximum (LGM). Salinity is usually determined at high precision via conductivity, which requires a larger volume of water than can be extracted from a sediment core, or via chloride titration, which yields lower than ideal precision. It has been demonstrated for water column samples that high precision density measurements can be used to determine salinity at the precision of a conductivity measurement using the equation of state of seawater. However, water column seawater has a relatively constant composition, in contrast to porewater, where variations from standard seawater composition occur. These deviations, which affect the equation of state, must be corrected for through precise measurements of each ion's concentration and knowledge of apparent partial molar density in seawater. We have developed a density-based method for determining porewater salinity that requires only 5 mL of sample, achieving density precisions of 10-6 g/mL. We have applied this method to porewater samples extracted from long cores collected along a N-S transect across the western North Atlantic (R/V Knorr cruise KN223). Density was determined to a precision of 2.3x10-6 g/mL, which translates to salinity uncertainty of 0.002 gms/kg if the effect of differences in composition is well constrained. Concentrations of anions (Cl-, and SO4-2) and cations (Na+, Mg+, Ca+2, and K+) were measured. To correct salinities at the precision required to unravel LGM Meridional Overturning Circulation, our ion precisions must be better than 0.1% for SO4-/Cl- and Mg+/Na+, and 0.4% for Ca+/Na+, and K+/Na+. Alkalinity, pH and Dissolved Inorganic Carbon of the porewater were determined to precisions better than 4% when ratioed to Cl-, and used to calculate HCO3-, and CO3-2. Apparent partial molar densities in seawater were determined experimentally. We compare the high precision salinity profiles determined using our new method to profiles determined from the traditional chloride titrations of parallel samples. Our technique provides a more accurate reconstruction of past salinity, informing questions of water mass composition and distribution during the LGM.

Concentration dependences of the density, viscosity, and refraction index of Cu(NO3)2 · 3H2O solutions in DMSO at 298 K

NASA Astrophysics Data System (ADS)

Mamyrbekova, A. K.

2013-03-01

Physicochemical properties (density, dynamic viscosity, refraction index) of the DMSO-Cu(NO3)2 · 3H2O system are studied in the concentration range of 0.01-2 M at 298 K. The refraction index of a solution of copper(II) nitrate in dimethylsulfoxide (DMSO) is measured at 288-318 K. The excess and partial molar volumes of the solvent and dissolved substance are calculated analytically.

Computer simulation of the carbon activity in austenite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murch, G.E.; Thorn, R.J.

1979-02-01

Carbon activity in austenite is described in terms of an Ising-like f.c.c. lattice gas model in which carbon interstitials repel only at the distance of nearest neighbors. A Monte Carlo simulation method in the petit canonical ensemble is employed to calculate directly the carbon activity as a function of composition and temperature. The computed activities are in satisfactory agreement with the experimental data, similarly for the decompostion of the activity to the partial molar enthalpy and entropy.

Clinical and Radiographic Evaluation of Allium sativum Oil as a New Medicament for Vital Pulp Treatment of Primary Teeth.

PubMed

Mohammad, Shukry Gamal; Raheel, Syed Ahmed; Baroudi, Kusai

2014-01-01

The objective of this study was to compare between the clinical and radiographic effects of Allium sativum oil and those of formocresol in vital pulpotomy in primary teeth. A total of 20 children age ranged from 4 to 8 years were included in the study. In every one of those children, the primary molars indicated for pulpotomy. Pulpotomy procedure was performed, and the radicular pulp tissue of one molar capped with A. sativum oil in a cotton pellet, whereas the other molar capped with formocresol, the teeth evaluated clinically and radiographically before and after 6 months, using standard clinical and radiographical criteria. Statistically, these results revealed no significant difference between the radiographic findings of vital pulpotomy in primary molars with the two medicaments was found. A. sativum oil offers a good healing potential, leaving the remaining pulp tissue healthy and functioning. Vital pulpotomy with allium sativa oil was given raise 90% success rate while that with formocresol was 85%. A. sativum oil is a biocompatible material that is compatible with vital human pulp tissue. It offers a good healing potential, leaving the remaining pulp tissue healthy and functioning.

Clinical and Radiographic Evaluation of Allium sativum Oil as a New Medicament for Vital Pulp Treatment of Primary Teeth

PubMed Central

Mohammad, Shukry Gamal; Raheel, Syed Ahmed; Baroudi, Kusai

2014-01-01

Background: The objective of this study was to compare between the clinical and radiographic effects of Allium sativum oil and those of formocresol in vital pulpotomy in primary teeth. Materials and Methods: A total of 20 children age ranged from 4 to 8 years were included in the study. In every one of those children, the primary molars indicated for pulpotomy. Pulpotomy procedure was performed, and the radicular pulp tissue of one molar capped with A. sativum oil in a cotton pellet, whereas the other molar capped with formocresol, the teeth evaluated clinically and radiographically before and after 6 months, using standard clinical and radiographical criteria. Statistically, these results revealed no significant difference between the radiographic findings of vital pulpotomy in primary molars with the two medicaments was found. Results: A. sativum oil offers a good healing potential, leaving the remaining pulp tissue healthy and functioning. Vital pulpotomy with allium sativa oil was given raise 90% success rate while that with formocresol was 85%. Conclusion: A. sativum oil is a biocompatible material that is compatible with vital human pulp tissue. It offers a good healing potential, leaving the remaining pulp tissue healthy and functioning. PMID:25628480

Cleaning and shaping curved root canals: Mtwo vs ProTaper instruments, a lab comparison.

PubMed

Kuzekanani, Maryam; Walsh, Laurence J; Yousefi, Mohammad Ali

2009-01-01

The purpose of this study was to compare root canal preparation in curved canals in molar teeth with the rotary NiTi Mtwo and ProTaper systems in terms of canal shape and smear layer. Mesiobuccal canals of 60 molar teeth with angles of curvature between 25 and 35 degrees were prepared with a torque controlled low speed engine; 30 canals for each system. Each individual instrument was used to prepare four root canals and the time required for preparation was recorded. Standardized radiographs were taken before and following instrumentation and used to determine changes in canal curvature. There was no significant difference in preparation time between the two systems. No instruments separated during use. The Mtwo system gave a statistically smaller change in canal curvature and thus was better for maintaining the original shape of the root canal, with less transportation (P less than 0.05). The greatest difference was seen for maxillary molar teeth. When prepared root canals were examined by SEM there was no difference between the two systems at the coronal, middle or apical thirds. Overall, the results of this study suggest that Mtwo instruments are preferable for situations where canals are curved, particularly for maxillary molars.

Piezosurgery vs High Speed Rotary Handpiece: a comparison between the two techniques in the impacted third molar surgery

PubMed Central

BARTULI, F.N.; LUCIANI, F.; CADDEO, F.; DE CHIARA, L.; DI DIO, M.; PIVA, P.; OTTRIA, L.; ARCURI, C.

2013-01-01

SUMMARY Objective The aim of the Study was to compare the impacted third molar surgical technique by means of the high speed rotary handpiece with the piezoelectric one. Materials and Methods 192 patients have been selected among those who had to undergo a third molar surgical extraction. These patients’ surgeries have been performed by means of one of the techniques, randomly chosen. Each patient has undergone the same analgesic therapy (paracetamol 1000 mg tablets). Each surgery has been performed by the same surgeon. The patients were asked to fill in a questionnaire concerning the postoperative pain (“happy face pain” rating scale). Results The average duration of the surgeries performed by means of the high speed rotary handpiece was 32 minutes, while the duration of the ones performed by means of the piezoelectric handpiece was much longer (54 minutes). The postoperative pain values were almost equal. Conclusions In conclusion, the osteotomy performed by means of the traditional technique still represents the gold standard in the impacted third molar surgery. The piezoelectric technique may be an effective choice, especially for the less skilled surgeons, in order to guarantee the protection of the delicate locoregional anatomical structures. PMID:23991279

Piezosurgery vs High Speed Rotary Handpiece: a comparison between the two techniques in the impacted third molar surgery.

PubMed

Bartuli, F N; Luciani, F; Caddeo, F; DE Chiara, L; DI Dio, M; Piva, P; Ottria, L; Arcuri, C

2013-01-01

The aim of the Study was to compare the impacted third molar surgical technique by means of the high speed rotary handpiece with the piezoelectric one. 192 patients have been selected among those who had to undergo a third molar surgical extraction. These patients' surgeries have been performed by means of one of the techniques, randomly chosen. Each patient has undergone the same analgesic therapy (paracetamol 1000 mg tablets). Each surgery has been performed by the same surgeon. The patients were asked to fill in a questionnaire concerning the postoperative pain ("happy face pain" rating scale). The average duration of the surgeries performed by means of the high speed rotary handpiece was 32 minutes, while the duration of the ones performed by means of the piezoelectric handpiece was much longer (54 minutes). The postoperative pain values were almost equal. In conclusion, the osteotomy performed by means of the traditional technique still represents the gold standard in the impacted third molar surgery. The piezoelectric technique may be an effective choice, especially for the less skilled surgeons, in order to guarantee the protection of the delicate locoregional anatomical structures.

Effect of Implant Diameter and Ridge Dimension on Stress Distribution in Mandibular First Molar Sites-A Photoelastic Study.

PubMed

Termeie, Deborah; Klokkevold, Perry R; Caputo, Angelo A

2015-10-01

The long-term clinical success of a dental implant is dependent upon maintaining sufficient osseointegration to resist forces of occlusion. The purpose of this study was to investigate the effect of implant diameter on stress distribution around screw-type dental implants in mandibular first molar sites using photoelastic models. The design included models with different buccal-lingual dimension. Twelve composite photoelastic models were assembled using 2 different resins to simulate trabecular and cortical bone. Half of the models were fabricated with average dimensions for ridge width and the other half with narrower buccal-lingual dimensions. One internal connection implant (13 mm length) with either a standard (4 mm), wide (5 mm), or narrow (3.3 mm) diameter was embedded in the first molar position of each photoelastic model. Half the implants were tapered and the other half were straight. Full gold crowns in the shape of a mandibular first molar were fabricated and attached to the implants. Vertical and angled loads of 15 and 30 pounds were applied to specific points on the crown. Wide-diameter implants produced the least stress in all ridges while narrow-diameter implants generated the highest stress, especially in narrow ridges. It may be that the volume and quality of bone surrounding implants influences stress distribution with a greater ratio of cortical to trabecular bone, thus providing better support. Models with wide-diameter implants loaded axially had a more symmetrical stress distribution compared to standard and narrow diameter implants. A more asymmetrical stress pattern developed along the entire implant length with angled loads. Implant diameter and ridge width had considerable influence on stress distribution. Narrow-diameter implants produced more stress than wide diameter implants in all conditions tested.

Solubility of oxygen in a seawater medium in equilibrium with a high-pressure oxy-helium atmosphere.

PubMed

Taylor, C D

1979-06-01

The molar oxygen concentration in a seawater medium in equilibrium with a high-pressure oxygen-helium atmosphere was measured directly in pressurized subsamples, using a modified version of the Winkler oxygen analysis. At a partial pressure of oxygen of 1 atm or less, its concentration in the aqueous phase was adequately described by Henry's Law at total pressures up to 600 atm. This phenomenon, which permits a straightforward determination of dissolved oxygen within hyperbaric systems, resulted from pressure-induced compensatory alterations in the Henry's Law variables rather than from a true obedience to the Ideal Gas Law. If the partial pressure of a gas contributes significantly to the hydrostatic pressure, Henry's Law is no longer adequate for determining its solubility within the compressed medium.

Dental age assessment of young Iranian adults using third molars: A multivariate regression study.

PubMed

Bagherpour, Ali; Anbiaee, Najmeh; Partovi, Parnia; Golestani, Shayan; Afzalinasab, Shakiba

2012-10-01

In recent years, a noticeable increase in forensic age estimations of living individuals has been observed. Radiologic assessment of the mineralisation stage of third molars is of particular importance, with regard to the relevant age group. To attain a referral database and regression equations for dental age estimation of unaccompanied minors in an Iranian population was the goal of this study. Moreover, determination was made concerning the probability of an individual being over the age of 18 in case of full third molar(s) development. Using the scoring system of Gleiser and Hunt, modified by Köhler, an investigation of a cross-sectional sample of 1274 orthopantomograms of 885 females and 389 males aged between 15 and 22 years was carried out. Using kappa statistics, intra-observer reliability was tested. With Spearman correlation coefficient, correlation between the scores of all four wisdom teeth, was evaluated. We also carried out the Wilcoxon signed-rank test on asymmetry and calculated the regression formulae. A strong intra-observer agreement was displayed by the kappa value. No significant difference (p-value for upper and lower jaws were 0.07 and 0.59, respectively) was discovered by Wilcoxon signed-rank test for left and right asymmetry. The developmental stage of upper right and upper left third molars yielded the greatest correlation coefficient. The probability of an individual being over the age of 18 is 95.6% for males and 100.0% for females in case four fully developed third molars are present. Taking into consideration gender, location and number of wisdom teeth, regression formulae were arrived at. Use of population-specific standards is recommended as a means of improving the accuracy of forensic age estimates based on third molars mineralisation. To obtain more exact regression formulae, wider age range studies are recommended. Copyright © 2012 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Postoperative socket irrigation with drinking tap water reduces the risk of inflammatory complications following surgical removal of third molars: a multicenter randomized trial.

PubMed

Ghaeminia, H; Hoppenreijs, Th J M; Xi, T; Fennis, J P; Maal, T J; Bergé, S J; Meijer, G J

2017-01-01

The primary aim of the present study was to evaluate the effectiveness of postoperative irrigation of the socket with drinking tap water on inflammatory complications following lower third molar removal. A multicenter randomized controlled trial was carried out from June 2013 to June 2014. In one arm of the study, patients were instructed to irrigate the tooth socket and surgical site with a Monoject® Curved 412 Tip Syringe (Tyco/healthcare-Kendall, Mansfield, MA, USA) with tap water. In a second arm of the study, the standard postoperative instructions did not include irrigation instructions. The incidences of alveolar osteitis and wound infection were recorded for each group and analyzed by the Fisher's exact test. A total of 280 patients with 333 mandibular third molars were analyzed. According to the intention-to-treat (ITT) analysis, inflammatory complications occurred in 18 cases in the Monoject® group (11.4 %) compared to 34 cases (19.1 %) in the control group (p = 0.04). These complications were associated with significant worse outcomes regarding quality of life, pain, and trismus and caused significantly more missed days of work or study. Female gender, age >26, bone removal, deep impacted third molars, less experienced surgeons, and a high amount of debris at the surgical site were also identified as risk factors for developing inflammatory complications following lower third molar removal. Irrigation of the surgical site with drinking tap water using a curved syringe following removal of third molars is effective in reducing the risk of inflammatory complications. Water is a very accessible, cost-effective irrigant without side effects and the results from this study have proven that it can be used to reduce the risk of inflammatory complications and associated morbidity following lower third molar removal.

The distribution and ultrastructure of the forming blood capillaries and the effect of apoptosis on vascularization in mouse embryonic molar mesenchyme.

PubMed

Yuan, Guohua; Zhang, Li; Yang, Guobin; Yang, Jingwen; Wan, Chunyan; Zhang, Lu; Song, Guangtai; Chen, Shuo; Chen, Zhi

2014-04-01

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.

Analysis of C-shaped canal systems in mandibular second molars using surgical operating microscope and cone beam computed tomography: A clinical approach.

PubMed

Chhabra, Sanjay; Yadav, Seema; Talwar, Sangeeta

2014-05-01

The study was aimed to acquire better understanding of C-shaped canal systems in mandibular second molar teeth through a clinical approach using sophisticated techniques such as surgical operating microscope and cone beam computed tomography (CBCT). A total of 42 extracted mandibular second molar teeth with fused roots and longitudinal grooves were collected randomly from native Indian population. Pulp chamber floors of all specimens were examined under surgical operating microscope and classified into four types (Min's method). Subsequently, samples were subjected to CBCT scan after insertion of K-files size #10 or 15 into each canal orifice and evaluated using the cross-sectional and 3-dimensional images in consultation with dental radiologist so as to obtain more accurate results. Minimum distance between the external root surface on the groove and initial file placed in the canal was also measured at different levels and statistically analyzed. Out of 42 teeth, maximum number of samples (15) belonged to Type-II category. A total of 100 files were inserted in 86 orifices of various types of specimens. Evaluation of the CBCT scan images of the teeth revealed that a total of 21 canals were missing completely or partially at different levels. The mean values for the minimum thickness were highest at coronal followed by middle and apical third levels in all the categories. Lowest values were obtained for teeth with Type-III category at all three levels. The present study revealed anatomical variations of C-shaped canal system in mandibular second molars. The prognosis of such complex canal anatomies can be improved by simultaneous employment of modern techniques such as surgical operating microscope and CBCT.

Digital radiographic evaluation of mandibular third molar for age estimation in young adults and adolescents of South Indian population using modified Demirjian's method

PubMed Central

Mohammed, Rezwana Begum; Koganti, Ravichandra; Kalyan, Siva V.; Tircouveluri, Saritha; Singh, Johar Rajvinder; Srinivasulu, Enganti

2014-01-01

In recent years, it has become increasingly important to determine the age of living people for a variety of reasons, including identifying criminal and legal responsibility and for many other social events such as birth certificate, marriage, beginning a job, joining the army and retirement Objectives: The aim of this study was to assess the developmental stages of mandibular third molar for estimation of dental age (DA) in different age groups and to evaluate the possible correlation between DA and chronological age (CA) in South Indian population. Materials and Methods: Digital orthopantomography of 330 subjects (165 males, 165 females) who fit the study and the criteria were obtained. Assessment of mandibular third molar development was performed using Demirjian et al., modified method and DA was assessed using tooth specific stages. Results and Discussion: The present study showed a significant correlation between DA and CA in both males and females. Third molar development commenced around 9 years and root completion takes place around 18.9 years in males and in females 9 years and 18.6 years respectively. Demirjian modified method underestimated the mean age of males by 0.8 years and females by 0.5 years and also showed that females mature earlier than males in selected population. Conclusion: Digital radiographic assessment of mandibular third molar development can be used to generate mean DA using Demirjian modified method and also the estimated age range for an individual of unknown CA. Since the Demirjian method is based on French-Canadian population, to enhance the accuracy of forensic age estimates based on third molar development, the use of population-specific standards is recommended. PMID:25177143

Digital radiographic evaluation of mandibular third molar for age estimation in young adults and adolescents of South Indian population using modified Demirjian's method.

PubMed

Mohammed, Rezwana Begum; Koganti, Ravichandra; Kalyan, Siva V; Tircouveluri, Saritha; Singh, Johar Rajvinder; Srinivasulu, Enganti

2014-09-01

In recent years, it has become increasingly important to determine the age of living people for a variety of reasons, including identifying criminal and legal responsibility and for many other social events such as birth certificate, marriage, beginning a job, joining the army and retirement. The aim of this study was to assess the developmental stages of mandibular third molar for estimation of dental age (DA) in different age groups and to evaluate the possible correlation between DA and chronological age (CA) in South Indian population. Digital orthopantomography of 330 subjects (165 males, 165 females) who fit the study and the criteria were obtained. Assessment of mandibular third molar development was performed using Demirjian et al., modified method and DA was assessed using tooth specific stages. The present study showed a significant correlation between DA and CA in both males and females. Third molar development commenced around 9 years and root completion takes place around 18.9 years in males and in females 9 years and 18.6 years respectively. Demirjian modified method underestimated the mean age of males by 0.8 years and females by 0.5 years and also showed that females mature earlier than males in selected population. Digital radiographic assessment of mandibular third molar development can be used to generate mean DA using Demirjian modified method and also the estimated age range for an individual of unknown CA. Since the Demirjian method is based on French-Canadian population, to enhance the accuracy of forensic age estimates based on third molar development, the use of population-specific standards is recommended.

Characterization of polymeric substance classes in cereal-based beverages using asymmetrical flow field-flow fractionation with a multi-detection system.

PubMed

Krebs, Georg; Becker, Thomas; Gastl, Martina

2017-09-01

Cereal-based beverages contain a complex mixture of various polymeric macromolecules including polysaccharides, peptides, and polyphenols. The molar mass of polymers and their degradation products affect different technological and especially sensory parameters of beverages. Asymmetrical flow field-flow fractionation (AF4) coupled with multi-angle light scattering (MALS) and refractive index detection (dRI) or UV detection (UV) is a technique for structure and molar mass distribution analysis of macromolecules commonly used for pure compound solutions. The objective of this study was to develop a systematic approach for identifying the polymer classes in an AF4//MALS/dRI/UV fractogram of the complex matrix in beer, a yeast-fermented cereal-based beverage. Assignment of fractogram fractions to polymer substance classes was achieved by targeted precipitations, enzymatic hydrolysis, and alignments with purified polymer standards. Corresponding effects on dRI and UV signals were evaluated according to the detector's sensitivities. Using these techniques, the AF4 fractogram of beer was classified into different fractions: (1) the low molar mass fraction was assigned to proteinaceous molecules with different degrees of glycosylation, (2) the middle molar mass fraction was attributed to protein-polyphenol complexes with a coelution of non-starch polysaccharides, and (3) the high molar mass fraction was identified as a mixture of the cell wall polysaccharides (i.e., β-glucan and arabinoxylan) with a low content of polysaccharide-protein association. In addition, dextrins derived from incomplete starch hydrolysis were identified in all fractions and over the complete molar mass range. The ability to assess the components of an AF4 fractogram is beneficial for the targeted design and evaluation of polymers in fermented cereal-based beverages and for controlling and monitoring quality parameters.

Automation of data processing and calculation of retention parameters and thermodynamic data for gas chromatography

NASA Astrophysics Data System (ADS)

Makarycheva, A. I.; Faerman, V. A.

2017-02-01

The analyses of automation patterns is performed and the programming solution for the automation of data processing of the chromatographic data and their further information storage with a help of a software package, Mathcad and MS Excel spreadsheets, is developed. The offered approach concedes the ability of data processing algorithm modification and does not require any programming experts participation. The approach provides making a measurement of the given time and retention volumes, specific retention volumes, a measurement of differential molar free adsorption energy, and a measurement of partial molar solution enthalpies and isosteric heats of adsorption. The developed solution is focused on the appliance in a small research group and is tested on the series of some new gas chromatography sorbents. More than 20 analytes were submitted to calculation of retention parameters and thermodynamic sorption quantities. The received data are provided in the form accessible to comparative analysis, and they are able to find sorbing agents with the most profitable properties to solve some concrete analytic issues.

Rapid orthodontic treatment after the ridge-splitting technique--a combined surgical-orthodontic approach for implant site development: case report.

PubMed

Amato, Francesco; Mirabella, A Davide; Borlizzi, Diego

2012-08-01

This article presents a clinical case of bilateral partial edentulism in the posterior mandible with severe horizontal and moderate vertical bone atrophy. A new technique using rapid orthodontics after ridge splitting is presented. The split-crest technique was carried out using piezosurgical instruments in the first molar and second premolar areas to widen the bone crest and open a channel for tooth movement. Immediately after, orthodontic appliances were used to move the first premolars distally and the second molars mesially into the surgical site. The rationale was to facilitate and accelerate orthodontic movement of the teeth, which is otherwise difficult in a cortical knife-edged ridge. The bone defect was filled with the alveolar bone of the adjacent teeth that were moved into the surgically opened path. Adequate bone volume for implant placement was generated in the first premolar area. Implants were then inserted, and the patient was rehabilitated.

Fabrication of fixed implant prostheses using function bite impression technique (FBI technique).

PubMed

Suzuki, Yasunori; Shimpo, Hidemasa; Ohkubo, Chikahiro; Kurtz, Kenneth S

2012-10-01

The patient was partially edentulous, lacking both the first mandibular molars. The FBI and the conventional impression technique were used for the fabrication of implant-fixed prosthesis replacing the right and left molars, respectively. In the FBI technique, the definitive impression was made under occlusal force and functionally generated path (FGP) recording at the same time. The right and left occlusal contact areas were compared after completing the implant-fixed prosthesis rehabilitation. It has been suggested that accuracy of the impression and maxillomandibular registration is necessary to ensure a satisfactory long-term clinical outcome. The transfer of the exact position of the implants to the working cast is even more important because implants lack the mobility of natural teeth. There are displacement differences between implants and natural teeth under occlusal force. The FBI technique may compensate for this difference in accuracy. Using the FBI technique, a precise prosthesis could be produced by completing simultaneously the maxillomandibular registration, impression and FGP. Copyright © 2012 Japan Prosthodontic Society. All rights reserved.

Equations for calculating hydrogeochemical reactions of minerals and gases such as CO2 at high pressures and temperatures

USGS Publications Warehouse

Appelo, C.A.J.; Parkhurst, David L.; Post, V.E.A.

2014-01-01

Calculating the solubility of gases and minerals at the high pressures of carbon capture and storage in geological reservoirs requires an accurate description of the molar volumes of aqueous species and the fugacity coefficients of gases. Existing methods for calculating the molar volumes of aqueous species are limited to a specific concentration matrix (often seawater), have been fit for a limited temperature (below 60 °C) or pressure range, apply only at infinite dilution, or are defined for salts instead of individual ions. A more general and reliable calculation of apparent molar volumes of single ions is presented, based on a modified Redlich–Rosenfeld equation. The modifications consist of (1) using the Born equation to calculate the temperature dependence of the intrinsic volumes, following Helgeson–Kirkham–Flowers (HKF), but with Bradley and Pitzer’s expression for the dielectric permittivity of water, (2) using the pressure dependence of the extended Debye–Hückel equation to constrain the limiting slope of the molar volume with ionic strength, and (3) adopting the convention that the proton has zero volume at all ionic strengths, temperatures and pressures. The modifications substantially reduce the number of fitting parameters, while maintaining or even extending the range of temperature and pressure over which molar volumes can be accurately estimated. The coefficients in the HKF-modified-Redlich–Rosenfeld equation were fitted by least-squares on measured solution densities.The limiting volume and attraction factor in the Van der Waals equation of state can be estimated with the Peng–Robinson approach from the critical temperature, pressure, and acentric factor of a gas. The Van der Waals equation can then be used to determine the fugacity coefficients for pure gases and gases in a mixture, and the solubility of the gas can be calculated from the fugacity, the molar volume in aqueous solution, and the equilibrium constant. The coefficients for the Peng–Robinson equations are readily available in the literature.The required equations have been implemented in PHREEQC, version 3, and the parameters for calculating the partial molar volumes and fugacity coefficients have been added to the databases that are distributed with PHREEQC. The ease of use and power of the formulation are illustrated by calculating the solubility of CO2 at high pressures and temperatures, and comparing with well-known examples from the geochemical literature. The equations and parameterizations are suitable for wide application in hydrogeochemical systems, especially in the field of carbon capture and storage.

Equations for calculating hydrogeochemical reactions of minerals and gases such as CO2 at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Appelo, C. A. J.; Parkhurst, D. L.; Post, V. E. A.

2014-01-01

Calculating the solubility of gases and minerals at the high pressures of carbon capture and storage in geological reservoirs requires an accurate description of the molar volumes of aqueous species and the fugacity coefficients of gases. Existing methods for calculating the molar volumes of aqueous species are limited to a specific concentration matrix (often seawater), have been fit for a limited temperature (below 60 °C) or pressure range, apply only at infinite dilution, or are defined for salts instead of individual ions. A more general and reliable calculation of apparent molar volumes of single ions is presented, based on a modified Redlich-Rosenfeld equation. The modifications consist of (1) using the Born equation to calculate the temperature dependence of the intrinsic volumes, following Helgeson-Kirkham-Flowers (HKF), but with Bradley and Pitzer’s expression for the dielectric permittivity of water, (2) using the pressure dependence of the extended Debye-Hückel equation to constrain the limiting slope of the molar volume with ionic strength, and (3) adopting the convention that the proton has zero volume at all ionic strengths, temperatures and pressures. The modifications substantially reduce the number of fitting parameters, while maintaining or even extending the range of temperature and pressure over which molar volumes can be accurately estimated. The coefficients in the HKF-modified-Redlich-Rosenfeld equation were fitted by least-squares on measured solution densities. The limiting volume and attraction factor in the Van der Waals equation of state can be estimated with the Peng-Robinson approach from the critical temperature, pressure, and acentric factor of a gas. The Van der Waals equation can then be used to determine the fugacity coefficients for pure gases and gases in a mixture, and the solubility of the gas can be calculated from the fugacity, the molar volume in aqueous solution, and the equilibrium constant. The coefficients for the Peng-Robinson equations are readily available in the literature. The required equations have been implemented in PHREEQC, version 3, and the parameters for calculating the partial molar volumes and fugacity coefficients have been added to the databases that are distributed with PHREEQC. The ease of use and power of the formulation are illustrated by calculating the solubility of CO2 at high pressures and temperatures, and comparing with well-known examples from the geochemical literature. The equations and parameterizations are suitable for wide application in hydrogeochemical systems, especially in the field of carbon capture and storage.

Delayed dental maturity in dentitions with agenesis of mandibular second premolars.

PubMed

Daugaard, S; Christensen, I J; Kjaer, I

2010-11-01

To evaluate dental maturity in the mandibular canine/premolar and molar innervation fields in children with agenesis of the 2nd mandibular premolar and to associate these findings with normal control material. Department of Orthodontics, Institute of Odontology, University of Copenhagen. Eighty-three panoramic radiographs (27 girls and 31 boys with agenesis of one mandibular 2nd premolar and 17 girls and eight boys with agenesis of both mandibular 2nd premolars) represented all mandibular second premolar agenesis cases from a material of 2847 radiographs. On each radiograph, dental maturity of all available mandibular premolars, canines and 2nd molars was evaluated and categorized in maturity stages according to Haavikko whose material served as control material. Descriptive statistics given by sample mean, standard deviation and range for each tooth stratified by gender and agenesis. Ninety-five percentage confidence limits and T-statistics were used. p-values <5% were considered significant. In unilateral agenesis, the canines are specifically delayed in both girls and boys, with a larger delay in girls (p=0.009). The second molar is not delayed in boys (p=0.98) but is in girls (p=0.04). The differences in delay for the canine compared to the second molar are significant for both girls and boys. The results show a considerable delay in tooth maturation within the canine/premolar innervation field predominantly in girls. The 2nd molar is delayed in girls but not in boys. © 2010 John Wiley & Sons A/S.

Lower molar and incisor displacement associated with mandibular remodeling.

PubMed

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

1997-01-01

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

Maxillary molar distalization with MGBM-system in class II malocclusion

PubMed Central

Maino, Giuliano; Mariani, Lisa; Bozzo, Ida; Maino, Giovanna; Caprioglio, Alberto

2013-01-01

Aims: Objective of this retrospective study was to evaluate the treatment effects of the MGBM-System (G.B Maino, A. Giannelly, R. Bernard, P. Mura), a new intraoral device to treat Class II malocclusions Materials and Methods: A retrospective study was conducted to compare the pre-distalization and post-distalization cephalograms and dental model casts of 30 patients (15 male, 15 female) with Class II malocclusion treated with MGBM-System. Mean age at the beginning of treatment was 13.3 years (standard deviation 3.3). Angular, horizontal and vertical measurements were recorded to monitor skeletal and dental-alveolar changes. Molar movements in horizontal plane were monitored by making dental measurements on dental model casts. Results: The MGBM-System produced a rapid molar distalization and Class II relationship was corrected in 8 months ± 2.05, on average. The maxillary first molars were distalized of 4.14 (PTV-6 cemento-enamel junction), associated with a significant distal axis incline of 10. 5° referred to SN and a significant intrusion of 1.3 mm (PP). As for anchorage loss, the first premolar exhibited a significant mesial movement of 0.86 mm, associated with a significant mesial axis incline of 2.46°. No significative changes in either sagittal or vertical skeletal relationship were observed. Conclusion: The results suggest that the MGBM-System is an efficient and reliable device for distalizing the maxillary permanent first and second molars. PMID:24987649

Incidence of lingual nerve paraesthesia following mandibular third molar surgery

PubMed Central

Lata, Jeevan; Tiwari, Arunesh K.

2011-01-01

Context: The surgical removal of impacted mandibular third molar is associated with minor but expected complications like pain, swelling, bruising and trismus. The lingual nerve damage sometimes occurs after the removal of mandibular third molar producing impaired sensation or permanent sensory loss. This complication is usually unexpected and unacceptable for the patients particularly if no prior warning has been given. Aims: The aim of the present clinical prospective study was to determine the clinical incidence of lingual nerve injury following mandibular third molar removal and to analyze possible factors for the lingual nerve injury. Settings and Design: Clinical prospective study in the Department of Oral Surgery, Punjab Government Dental College and Hospital, Amritsar. Materials and Methods: Ninety patients were selected randomly, amongst the patients, who reported to our department from January 2009 to December 2009 for the surgical removal of impacted mandibular third molar. To minimize the risk of lingual nerve injury, the standard terence wards incision was made in all cases and only buccal flap was raised. Statistical Analysis: The small number of paraesthesia precluded statistical analysis. Results: Out of 90 patients, six patients were diagnosed with lingual nerve paraesthesia. The overall incidence rate of lingual nerve injury was 6.6%. Conclusions: It can be concluded that lingual nerve paraesthesia can occur with or without reflection of lingual flap in spite of all the measures taken to protect it. It may be contributed to the fact of anatomical variations of lingual nerve. PMID:22639500

Evaluation of single-tooth implants in the second molar region: a 5-year life-table analysis of a retrospective study.

PubMed

Koo, Ki-Tae; Wikesjö, Ulf M E; Park, Jang-Yeol; Kim, Tae-Il; Seol, Yang-Jo; Ku, Young; Rhyu, In-Chul; Chung, Chong-Pyoung; Lee, Yong-Moo

2010-09-01

To our knowledge, no study has evaluated the success or survival rate of single-tooth implants that replaced missing maxillary and mandibular second molars. The purpose of the present study was to evaluate the 1- to 5-year cumulative survival rate (CSR) for single-tooth implants placed in the second molar region and the effects of associated factors. Four hundred eighty-nine patients (298 males and 191 females; age range: 23 to 91 years; mean age: 47 years) who were admitted to the Seoul National University Dental Hospital between March 2003 and July 2008 and treated with single-tooth implants in the second molar region (227 maxillary implants and 294 mandibular implants; total: 521 implants) were included in the study. Thirty-two subjects received two implants each. A 1- to 5-year CSR was calculated using a life-table analysis. A comparison of CSRs between maxillary versus mandibular implants, one-stage versus two-stage implants, short (10 mm) implants, and standard-diameter (or=5.0 mm) implants was performed using Wilcoxon (Gehan) statistics. P <0.05 was considered significant. Fifteen of the 521 implants were lost between insertion and the follow-up examinations. The 1- to 5-year CSR was 95.1%. There were no statistically significant differences in CSRs between implants placed in maxillas and mandibles (96.3% versus 94.9%, respectively; P = 0.084), one- and two-stage implants (95.6% versus 94.7%, respectively; P = 0.267), short and long implants (100% versus 95.1%, respectively; P = 0.582), and standard- and wide-diameter implants (93.8% versus 96.8%, respectively; P = 0.065). Within the limitations of the study, the placement of single-tooth implants in the second molar region was an effective and reliable treatment modality. Also, associated factors such as implant diameter, length, and location (the maxilla versus the mandible) may not have an impact on the long-term success of implants.

Octanol-Water Partition Coefficient from 3D-RISM-KH Molecular Theory of Solvation with Partial Molar Volume Correction.

PubMed

Huang, WenJuan; Blinov, Nikolay; Kovalenko, Andriy

2015-04-30

The octanol-water partition coefficient is an important physical-chemical characteristic widely used to describe hydrophobic/hydrophilic properties of chemical compounds. The partition coefficient is related to the transfer free energy of a compound from water to octanol. Here, we introduce a new protocol for prediction of the partition coefficient based on the statistical-mechanical, 3D-RISM-KH molecular theory of solvation. It was shown recently that with the compound-solvent correlation functions obtained from the 3D-RISM-KH molecular theory of solvation, the free energy functional supplemented with the correction linearly related to the partial molar volume obtained from the Kirkwood-Buff/3D-RISM theory, also called the "universal correction" (UC), provides accurate prediction of the hydration free energy of small compounds, compared to explicit solvent molecular dynamics [ Palmer , D. S. ; J. Phys.: Condens. Matter 2010 , 22 , 492101 ]. Here we report that with the UC reparametrized accordingly this theory also provides an excellent agreement with the experimental data for the solvation free energy in nonpolar solvent (1-octanol) and so accurately predicts the octanol-water partition coefficient. The performance of the Kovalenko-Hirata (KH) and Gaussian fluctuation (GF) functionals of the solvation free energy, with and without UC, is tested on a large library of small compounds with diverse functional groups. The best agreement with the experimental data for octanol-water partition coefficients is obtained with the KH-UC solvation free energy functional.

Development of isothermal-isobaric replica-permutation method for molecular dynamics and Monte Carlo simulations and its application to reveal temperature and pressure dependence of folded, misfolded, and unfolded states of chignolin

NASA Astrophysics Data System (ADS)

Yamauchi, Masataka; Okumura, Hisashi

2017-11-01

We developed a two-dimensional replica-permutation molecular dynamics method in the isothermal-isobaric ensemble. The replica-permutation method is a better alternative to the replica-exchange method. It was originally developed in the canonical ensemble. This method employs the Suwa-Todo algorithm, instead of the Metropolis algorithm, to perform permutations of temperatures and pressures among more than two replicas so that the rejection ratio can be minimized. We showed that the isothermal-isobaric replica-permutation method performs better sampling efficiency than the isothermal-isobaric replica-exchange method and infinite swapping method. We applied this method to a β-hairpin mini protein, chignolin. In this simulation, we observed not only the folded state but also the misfolded state. We calculated the temperature and pressure dependence of the fractions on the folded, misfolded, and unfolded states. Differences in partial molar enthalpy, internal energy, entropy, partial molar volume, and heat capacity were also determined and agreed well with experimental data. We observed a new phenomenon that misfolded chignolin becomes more stable under high-pressure conditions. We also revealed this mechanism of the stability as follows: TYR2 and TRP9 side chains cover the hydrogen bonds that form a β-hairpin structure. The hydrogen bonds are protected from the water molecules that approach the protein as the pressure increases.

Thermodynamic properties of calcium-bismuth alloys determined by emf measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, H; Boysen, DA; Bradwell, DJ

2012-01-15

The thermodynamic properties of Ca-Bi alloys were determined by electromotive force (emf) measurements to assess the suitability of Ca-Bi electrodes for electrochemical energy storage applications. Emf was measured at ambient pressure as a function of temperature between 723 K and 1173 K using a Ca(s)vertical bar CaF2(s)vertical bar Ca(in Bi) cell for twenty different Ca-Bi alloys spanning the entire range of composition from chi(Ca) = 0 to 1. Reported are the temperature-independent partial molar entropy and enthalpy of calcium for each Ca-Bi alloy. Also given are the measured activities of calcium, the excess partial molar Gibbs energy of bismuth estimatedmore » from the Gibbs-Duhem equation, and the integral change in Gibbs energy for each Ca-Bi alloy at 873 K, 973 K, and 1073 K. Calcium activities at 973 K were found to be nearly constant at a value a(Ca) = 1 x 10(-8) over the composition range chi(Ca) = 0.32-0.56, yielding an emf of similar to 0.77 V. Above chi(Ca) = 0.62 and coincident with Ca5Bi3 formation, the calcium activity approached unity. The Ca-Bi system was also characterized by differential scanning calorimetry over the entire range of composition. Based upon these data along with the emf measurements, a revised Ca-Bi binary phase diagram is proposed. (C) 2011 Elsevier Ltd. All rights reserved.« less

Modeling solubility of CO2/hydrocarbon gas in ionic liquid ([emim][FAP]) using Aspen Plus simulations.

PubMed

Bagchi, Bishwadeep; Sati, Sushmita; Shilapuram, Vidyasagar

2017-08-01

The Peng-Robinson equation of state with quadratic van der Waals (vdW) mixing rule model was chosen to perform the thermodynamic calculations in Flash3 column of Aspen Plus to predict the solubility of CO 2 or any one of the hydrocarbons (HCs) among methane, ethane, propane, and butane in an ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([emim][FAP]). Bubble point pressure, solubility, bubble point temperature, fugacity, and partial molar volume at infinite dilution were obtained from the simulations, and enthalpy of absorption, Gibbs free energy of solvation, and entropy change of absorption were estimated by thermodynamic relations. Results show that carbon chain length has a significant effect on the bubble point pressure. Methane has the highest bubble point pressure among all the considered HCs and CO 2 . The bubble point pressure and fugacity variation with temperature is different for CO 2 as compared to HCs for mole fractions above 0.2. Two different profiles are noticed for enthalpy of absorption when plotted as a function of mole fraction of gas soluble in IL. Partial molar volume of CO 2 decreases with increase in temperature in [emim][FAP], while it is increased for HCs. Bubble point temperature decreases with increase in the mole fraction of the solute. Entropy of solvation increases with temperature till a particular value followed by a decrease with further increase in temperature. Gibbs free energy change of solvation showed that the process of solubility was spontaneous.

The density, compressibility and seismic velocity of hydrous melts at crustal and upper mantle conditions

NASA Astrophysics Data System (ADS)

Ueki, K.; Iwamori, H.

2015-12-01

Various processes of subduction zone magmatism, such as upward migration of partial melts and fractional crystallization depend on the density of the hydrous silicate melt. The density and the compressibility of the hydrous melt are key factors for the thermodynamic calculation of phase relation of the hydrous melt, and the geophysical inversion to predict physicochemical conditions of the melting region based on the seismic velocity. This study presents a new model for the calculations of the density of the hydrous silicate melts as a function of T, P, H2O content and melt composition. The Birch-Murnaghan equation is used for the equation of state. We compile the experimentally determined densities of various hydrous melts, and optimize the partial molar volume, compressibility, thermal expansibility and its pressure derivative, and K' of the H2O component in the silicate melt. P-T ranges of the calibration database are 0.48-4.29 GPa and 1033-2073 K. As such, this model covers the P-T ranges of the entire melting region of the subduction zone. Parameter set provided by Lange and Carmichael [1990] is used for the partial molar volume and KT value of the anhydrous silicate melt. K' of anhydrous melt is newly parameterized as a function of SiO2 content. The new model accurately reproduces the experimentally determined density variations of various hydrous melts from basalt to rhyolite. Our result shows that the hydrous melt is more compressive and less dense than the anhydrous melt; with the 5 wt% of H2O in melt, density and KT decrease by ~10% and ~30% from those of the anhydrous melt, respectively. For the application of the model, we calculated the P-wave velocity of the hydrous melt. With the 5 wt% of H2O, P-wave velocity of the silicate melt decreases by >10%. Based on the melt P-wave velocity, we demonstrate the effect of the melt H2O content on the seismic velocity of the partially molten zone of the subduction zone.

Occlusion of artificial teeth in partial dentures in the "chewing center"--first exploratory population-based evaluations.

PubMed

Kordass, B; Ruge, S; Quooss, A; Hugger, A; Mundt, T

2014-01-01

Occlusal performance is a substantial determinant of the quality of dental prosthetic restorations. In the follow-up (SHIP 1) to the Study of Health in Pomerania (SHIP), a representative population of 3300 subjects was studied in the first exploratory evaluation of the occlusion of artificial teeth in the chewing center (first molar region) of partial dentures. A digital analysis of interocclusal records of habitual intercuspation position (ICP) was performed using the Greifswald Digital Analyzing System (GEDAS), a software package that identifies contact points as transparent areas. 562 subjects (280 men aged 61.7 ± 11.9 years and 282 women aged 60.7 ± 10.7 years) had maxillary removable partial dentures (RPDs), and 619 (271 men aged 65.0 ± 11.5 years and 348 women aged 62.4 ± 10.6 years) had mandibular RPDs. Most RPDs were retained with either attachment retainers (11.7% maxilla, 11.7% mandible), cast clasps (38.4% maxilla, 40.7% mandible), telescopes with double crowns (15.7% maxilla, 19.1% mandible), or wrought wire clasps (16.4% maxilla, 8.2% mandible). Some had a combination of different retention elements. The mean number of artificial teeth was 7.8 ± 2.9 in the maxilla and 7.5 ± 3.0 in the mandible. Only the artificial teeth (first molars) in mandibular partial dentures showed differences in the frequency of occlusal contacts between groups (chi-square test). Of these, telescopic crown-retained RPDs had the highest frequency of occlusal contacts (74.4% at tooth 36 and 77.1% at tooth 46), and wrought wire-retained RPDs had the lowest (48.4% at tooth 36 and 45.2% at tooth 46). The results for RPDs with a free-end saddle were comparable and analogous; contact frequencies for those with an interdental saddle did not differ significantly. Notably, the overall frequency of occlusal contacts was greater for tooth 46 (62.9%) than for tooth 36. In conclusion, when replacing teeth in the chewing center, particularly in the mandible, telescopic crown-retained RPDs offer a distinct advantage in terms of occlusal contacts and thus provide better occlusal stability.

[Three-dimensional finite analysis of the stress in first mandibular molar with composite class I restoration when various mixing ratios of bases were used].

PubMed

Zhou, Lan; Yang, Jin-Bo; Liu, Dan; Liu, Zhan; Chen, Ying; Gao, Bo

2008-06-01

To analyze the possible damage to the remaining tooth and composite restorations when various mixing ratios of bases were used. Testing elastic modulus and poission's ratio of glass-ionomer Vitrebond and self-cured calcium hydroxide Dycal with mixing ratios of 1:1, 3:4, 4:3. Micro-CT was used to scan the first mandibular molar, and the three-dimensional finite element model of the first permanent mandibular molar with class I cavity was established. Analyzing the stress of tooth structure, composite and base cement under physical load when different mixing ratios of base cement were used. The elastic modulus of base cement in various mixing ratios was different, which had the statistic significance. The magnitude and location of stress in restored tooth made no differences when the mixing ratios of Vitrebond and Dycal were changed. The peak stress and spreading area in the model with Dycal was more than that with Vitrebond. Changing the best mixing ratio of base cement can partially influence the mechanistic character, but make no differences on the magnitude and location of stress in restored tooth. During the treatment of deep caries, the base cement of the elastic modulus which is proximal to the dentin and restoration should be chosen to avoid the fracture of tooth or restoration.

[Determination of solubility parameters for asymmetrical dicationic ionic liquids by inverse gas chromatography].

PubMed

Wang, Jun; Yang, Xuzhao; Wu, Jinchao; Song, Hao; Zou, Wenyuan

2015-12-01

Inverse gas chromatographic (IGC) technology was used to determine the solubility parameters of three asymmetrical dicationic ionic liquids ([ PyC5Pi] [ NTf2]2, [MpC5Pi] [NTf2]2 and [PyC6Pi] [NTf2]2) at 343.15-363.15 K. Five alkanes were applied as test probes including octane (n-C8) , decane (n-C10), dodecane (n-C12), tetradecane (n-C14), hexadecane (n-C16). Some thermodynamic parameters were obtained by IGC data analysis, such as the specific retention volumes of the solvents (V0(g)), the molar enthalpies of sorption (ΔHs(1)), the partial molar enthalpies of mixing at infinite dilution (ΔH∞91)), the molar enthalpies of vaporization (ΔH)v)), the activity coefficients at infinite dilution (Ω∞(1)), and Flory-Huggins interaction parameters (χ∞(12)) between ionic liquids and probes. The solubility parameters (δ2) of the three dicationic ionic liquids at room temperature (298.15 K) were 28.52-32.66 (J x cm(-3)) ½. The solubility parameters (δ2) of cationic structure with 4-methyl morpholine are bigger than those of the cationic structure with pyridine. The bigger the solubility parameter (δ2) is, the more the carbon numbers of linking group of the ionic liquids are. The results are of great importance to the study of the solution behavior and the applications of ionic liquid.

The Artificial Hamiltonian, First Integrals, and Closed-Form Solutions of Dynamical Systems for Epidemics

NASA Astrophysics Data System (ADS)

Naz, Rehana; Naeem, Imran

2018-03-01

The non-standard Hamiltonian system, also referred to as a partial Hamiltonian system in the literature, of the form {\\dot q^i} = {partial H}/{partial {p_i}},\\dot p^i = - {partial H}/{partial {q_i}} + {Γ ^i}(t,{q^i},{p_i}) appears widely in economics, physics, mechanics, and other fields. The non-standard (partial) Hamiltonian systems arise from physical Hamiltonian structures as well as from artificial Hamiltonian structures. We introduce the term `artificial Hamiltonian' for the Hamiltonian of a model having no physical structure. We provide here explicitly the notion of an artificial Hamiltonian for dynamical systems of ordinary differential equations (ODEs). Also, we show that every system of second-order ODEs can be expressed as a non-standard (partial) Hamiltonian system of first-order ODEs by introducing an artificial Hamiltonian. This notion of an artificial Hamiltonian gives a new way to solve dynamical systems of first-order ODEs and systems of second-order ODEs that can be expressed as a non-standard (partial) Hamiltonian system by using the known techniques applicable to the non-standard Hamiltonian systems. We employ the proposed notion to solve dynamical systems of first-order ODEs arising in epidemics.

Determination of the molar mass of argon from high-precision acoustic comparisons

NASA Astrophysics Data System (ADS)

Feng, X. J.; Zhang, J. T.; Moldover, M. R.; Yang, I.; Plimmer, M. D.; Lin, H.

2017-06-01

This article describes the accurate determination of the molar mass M of a sample of argon gas used for the determination of the Boltzmann constant. The method of one of the authors (Moldover et al 1988 J. Res. Natl. Bur. Stand. 93 85-144) uses the ratio of the square speed of sound in the gas under analysis and in a reference sample of known molar mass. A sample of argon that was isotopically-enriched in 40Ar was used as the reference, whose unreactive impurities had been independently measured. The results for three gas samples are in good agreement with determinations by gravimetric mass spectrometry; (  -  1)  =  (-0.31  ±  0.69)  ×  10-6, where the indicated uncertainty is one standard deviation that does not account for the uncertainties from the acoustic and mass-spectroscopy references.

Refractive index, molar refraction and comparative refractive index study of propylene carbonate binary liquid mixtures.

PubMed

Wankhede, Dnyaneshwar Shamrao

2012-06-01

Refractive indices (n) have been experimentally determined for the binary liquid-liquid mixtures of Propylene carbonate (PC) (1) with benzene, ethylbenzene, o-xylene and p-xylene (2) at 298.15, 303.15 and 308.15 K over the entire mole fraction range. The experimental values of n are utilised to calculate deviation in refractive index (Δn), molar refraction (R) and deviation in molar refraction (ΔR). A comparative study of Arago-Biot (A-B), Newton (NW), Eyring and John (E-J) equations for determining refractive index of a liquid has been carried out to test their validity for all the binary mixtures over the entire composition range at 298.15 K. Comparison of various mixing relations is represented in terms of average deviation (AVD). The Δn and ΔR values have been fitted to Redlich-Kister equation at 298.15 K and standard deviations have been calculated. The results are discussed in terms of intermolecular interactions present amongst the components.

Keep It in Proportion.

ERIC Educational Resources Information Center

Snider, Richard G.

1985-01-01

The ratio factors approach involves recognizing a given fraction, then multiplying so that units cancel. This approach, which is grounded in concrete operational thinking patterns, provides a standard for science ratio and proportion problems. Examples are included for unit conversions, mole problems, molarity, speed/density problems, and…

The Correlation of Standard Entropy with Enthalpy Supplied from 0 to 298.15 K

ERIC Educational Resources Information Center

Lambert, Frank L.; Leff, Harvey S.

2009-01-01

As a substance is heated at constant pressure from near 0 K to 298 K, each incremental enthalpy increase, dH, alters entropy by dH/T, bringing it from approximately zero to its standard molar entropy S degrees. Using heat capacity data for 32 solids and CODATA results for another 45, we found a roughly linear relationship between S degrees and…

A DFT study on the enthalpies of thermite reactions and enthalpies of formation of metal composite oxide

NASA Astrophysics Data System (ADS)

Zhang, Yu-ying; Wang, Meng-jie; Chang, Chun-ran; Xu, Kang-zhen; Ma, Hai-xia; Zhao, Feng-qi

2018-05-01

The standard thermite reaction enthalpies (ΔrHmθ) for seven metal oxides were theoretically analyzed using density functional theory (DFT) under five different functional levels, and the results were compared with experimental values. Through the comparison of the linear fitting constants, mean error and root mean square error, the Perdew-Wang functional within the framework of local density approximation (LDA-PWC) and Perdew-Burke-Ernzerhof exchange-correlation functional within the framework of generalized gradient approximation (GGA-PBE) were selected to further calculate the thermite reaction enthalpies for metal composite oxides (MCOs). According to the Kirchhoff formula, the standard molar reaction enthalpies for these MCOs were obtained and their standard molar enthalpies of formation (ΔfHmθ) were finally calculated. The results indicated that GGA-PBE is the most suitable one out of the total five methods to calculate these oxides. Tungstate crystals present the maximum deviation of the enthalpies of thermite reactions for MCOs and these of their physical metal oxide mixtures, but ferrite crystals are the minimum. The correlation coefficients are all above 0.95, meaning linear fitting results are very precise. And the molar enthalpies of formation for NiMoO4, CuMoO4, PbZrO3 (Pm/3m), PbZrO3 (PBA2), PbZrO3 (PBam), MgZrO3, CdZrO3, MnZrO3, CuWO4 and Fe2WO6 were first obtained as -1078.75, -1058.45, -1343.87, -1266.54, -1342.29, -1333.03, -1210.43, -1388.05, -1131.07 and - 1860.11 kJ·mol-1, respectively.

Comparison of the EndoVac system and conventional needle irrigation on removal of the smear layer in primary molar root canals.

PubMed

Buldur, B; Kapdan, A

2017-09-01

This study aimed to compare the EndoVac system and conventional needle irrigation in removing smear layer (SR) from primary molar root canals. Fifty extracted human primary second molar roots were instrumented up to an apical size of 0.04/35 and randomly divided into two main groups; Group 1: EndoVac system (n = 25) and Group 2: Conventional needle irrigation (n = 25) and three subgroups (a) NaOCl + ethylenediaminetetraacetic acid (EDTA) (n = 20) (b) ozonated water (OW) + EDTA (n = 20) and (c) saline (control, n = 10). After a standardized final irrigation protocol performed for all teeth, scanning electron microscope images were taken at ×1000 magnification for each thirds of each root canal. Data were analyzed by the weighted kappa, Kruskal-Wallis, and Wilcoxon signed rank tests. EndoVac was more effective than conventional needle in the removal of SR from the apical third of the root canal system (P < 0.05). The OW + EDTA regimen provided similar SR removal compared with NaOCl + EDTA. EndoVac has better performance than conventional needle irrigation in the removal of the SR in the apical thirds of the primary molar root canals. As a final irrigation regimen, the OW + EDTA regimen is as effective as the NaOCl + EDTA regimen.

Purification and Partial Characterization of Two Soluble NAD(P)H Dehydrogenases from Arum maculatum Mitochondria 1

PubMed Central

Chauveau, Michèle; Lance, Claude

1991-01-01

Two enzyme systems carrying out the oxidation of NAD(P)H in the presence of various electron acceptors have been isolated and partially characterized from the supernatant of frozen-thawed mitochondria from Arum maculatum spadices. The two systems contain flavoproteins and differ by their ability to oxidize NADH or NADPH, optimum pH and pI values, sensitivity to Ca2+ and EGTA, denaturation by 4 molar urea, molecular mass, and number of subunits. These properties, together with methodological considerations, are compatible with the location of these enzyme activities on the outer surface of the inner mitochondrial membrane, and support the hypothesis of the existence of two separate dehydrogenases responsible for the mitochondrial oxidation of cytosolic NADH and NADPH. Images Figure 1 Figure 3 Figure 7 PMID:16668075

Fusion Welding Research.

DTIC Science & Technology

1985-04-30

rA( LA - AH) [watt cm 2] f3 ,5_ - . where " . ._.... L is the heat of evaporation of pure A and ~o ---30 3opo WA is the partial molar heat of mixing...steel; average voltage II V, current 2t atEL = rA( LA - ’-A)twatt cm 2 s], 14] 15 A; averae ample size I g. where t is time. In most cases XHA is small...B. Gates, Metrologia 17(3), 103 (1981). 7. R. D. Hudson, Jr., Infrared Engineering, Chap. 2, John Wiley, New York (1969). 8 R. Siegel and J. R

Effect of the Army Oral Health Maintenance Program (AOHMP) on the Dental Health Status of Army Personnel. AOHMP Evaluation Study. Part 3. Dental Care Requirements of Active Duty Army Personnel, 1978

DTIC Science & Technology

1979-06-01

endodontics , crown and bridge, full and partial dentures, and periodontal therapy , account for about one- third of the time requirements for the...Examiners indicated the numbers of restorations, extractions, teeth needing endodontic therapy , units of crown and bridge, complete den- tures...might be that lieutenants and captains are in a younger age range where the removal of third molars is usually recommended. (3) In the care need areas

Factors that affect molecular weight distribution of Suwannee river fulvic acid as determined by electrospray ionization/mass spectrometry

USGS Publications Warehouse

Rostad, Colleen E.; Leenheer, Jerry A.

2004-01-01

Effects of methylation, molar response, multiple charging, solvents, and positive and negative ionization on molecular weight distributions of aquatic fulvic acid were investigated by electrospray ionization/mass spectrometry. After preliminary analysis by positive and negative modes, samples and mixtures of standards were derivatized by methylation to minimize ionization sites and reanalyzed.Positive ionization was less effective and produced more complex spectra than negative ionization. Ionization in methanol/water produced greater response than in acetonitrile/water. Molar response varied widely for the selected free acid standards when analyzed individually and in a mixture, but after methylation this range decreased. After methylation, the number average molecular weight of the Suwannee River fulvic acid remained the same while the weight average molecular weight decreased. These differences are probably indicative of disaggregation of large aggregated ions during methylation. Since the weight average molecular weight decreased, it is likely that aggregate formation in the fulvic acid was present prior to derivatization, rather than multiple charging in the mass spectra.

Challenges in analysis of high-molar mass dextrans: comparison of HPSEC, AsFlFFF and DOSY NMR spectroscopy.

PubMed

Maina, Ndegwa Henry; Pitkänen, Leena; Heikkinen, Sami; Tuomainen, Päivi; Virkki, Liisa; Tenkanen, Maija

2014-01-01

Dilute solutions of various dextran standards, a high-molar mass (HMM) commercial dextran from Leuconostoc spp., and HMM dextrans isolated from Weissella confusa and Leuconostoc citreum were analyzed with high-performance size-exclusion chromatography (HPSEC), asymmetric flow field-flow fractionation (AsFlFFF), and diffusion-ordered NMR spectroscopy (DOSY). HPSEC analyses were performed in aqueous and dimethyl sulfoxide (DMSO) solutions, while only aqueous solutions were utilized in AsFlFFF and DOSY. The study showed that all methods were applicable to dextran analysis, but differences between the aqueous and DMSO-based solutions were obtained for HMM samples. These differences were attributed to the presence of aggregates in aqueous solution that were less prevalent in DMSO. The study showed that DOSY provides an estimate of the size of HMM dextrans, though calibration standards may be required for each experimental set-up. To our knowledge, this is the first study utilizing these three methods in analyzing HMM dextrans. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pressure-dependent boron isotopic fractionation observed by column chromatography

NASA Astrophysics Data System (ADS)

Musashi, M.; Oi, T.; Matsuo, M.; Nomura, M.

2007-12-01

Boron isotopic fractionation factor ( S ) between boron taken up in strongly basic anion exchange resin and boron in aqueous solution was determined by breakthrough column chromatography at 5 and 17 MPa at 25°C, using 0.1 mmol/L boric acid solution as feed solution. The S values obtained were 1.018 and 1.012, respectively, which were smaller than the value reported by using the same chromatographic method at atmospheric pressure at 25°C with the boron concentration of 10 mmol/L, but were larger than the values at the same condition with much higher concentration of 100 and 501 mmol/L, indicating that borate-polymerization reducing the isotopic fractionation was negligible. However, calculations based on the theory of isotope distribution between two phases estimated that 21% (5MPa) and 47% (17MPa) of boron taken up in the resin phase was in the three-coordinated B(OH)3-form, instead of in the four-coordinated B(OH)4--form, at high pressures even with the very diluted solution. We discussed this discrepancy by introducing (1) hydration or (2) a partial molar volume difference between isotopic molecules. It was inferred that borate ions were partially dehydrated upon transfer from the solution phase to the resin phase at high pressures, which resulted in smaller S values compared with those at the atmospheric pressure. Alternatively, it was likely that the S value decreased with increasing pressure, because the difference of the partial isotopic molar volumes between 10B(OH)3 and 11B(OH)3 was larger than that between 10B(OH)4- and 11B(OH)4-. If either will be the case, the influence of a pressure upon the isotope effect may not be negligible for boron isotopic exchange equilibrium. This knowledge is crucial for the principle of the boron isotopic pH-metry reconstructing a chemical variation at the paleo-deep oceanic environment where the early life may have been evolved.

Morphological assessment of the mandibular canal trajectory in edentate subjects.

PubMed

Nimigean, Victor; Sîrbu, Valentin Daniel; Nimigean, Vanda Roxana; Bădiţă, Daniela Gabriela; Poll, Alexandru; Moraru, Simona Andreea; Păun, Diana Loreta

2018-01-01

The mandibular canal and its content represent the vital structure, which can complicate dentoalveolar surgical procedures in the posterior region of the mandible. The purpose of the present study was to determine the path the mandibular canal takes in relation to the horizontal and the vertical anatomical reference planes in edentate subjects, in order to minimize the risk of affecting its neurovascular content during various oral surgery procedures. Morphometric evaluations were performed on 12 dried fully edentulous human mandibles and on cone-beam computed tomography (CBCT) cross-sectional images of the mandible, from 20 patients with either partial or complete edentulism. Both methods were utilized, in three target areas (corresponding to the second premolar, to the first molar and to the second molar regions), in order to measure the distance between the mandibular canal and the following reference points: (i) the lateral (buccal) surface of the mandible (MC-BS distance); (ii) the medial (lingual) surface of the mandible (MC-LS distance); (iii) the alveolar surface of the mandible (MC-AS distance). The results were statistically processed in Stata MP/13 software package using analysis of variance (ANOVA) test. The mandibular canal crossed the trabecular bone from the posterior towards the anterior, and from the lingual towards the buccal, reaching the premolar region, distal to the mental foramen, where it was located in the centre of the trabecular bone, main topographic pattern encountered in 27 (84.37%) of the cases. In five (15.63%) of the cases, in the premolar region, the mandibular canal was located near the buccal cortical plate. The mandibular canal descended from the second molar region towards the premolar region, main topographic pattern found in 28 (87.5%) of the cases. In four (12.5%) cases, the mandibular canal had a descending trajectory in the molar regions and it took a slightly ascending course in the premolar region. According to the results, the second molar region represents the highest risk area in the accidental injury to the content of the mandibular canal, during various oral surgery procedures.

Physico-chemical properties of binary mixtures of aliphatic and aromatic solvents at 313 K on acoustical data

NASA Astrophysics Data System (ADS)

Dahire, S. L.; Morey, Y. C.; Agrawal, P. S.

2015-12-01

Density (ρ), viscosity (η), and ultrasonic velocity ( U) of binary mixtures of aliphatic solvents like dimethylformamide (DMF) and dimethylsulfoxide (DMSO) with aromatic solvents viz. chlorobenzene (CB), bromobenzene (BB), and nitrobenzene (NB) have been determined at 313 K. These parameters were used to calculate the adiabatic compressibility (β), intermolecular free length ( L f), molar volume ( V m), and acoustic impedance ( Z). From the experimental data excess molar volume ( V m E ), excess intermolecular free length ( L f E )), excess adiabatic compressibility (βE), and excess acoustic impedance ( Z E) have been computed. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations (σ).

Study of intermolecular interactions in binary mixtures of ethanol in methanol

NASA Astrophysics Data System (ADS)

Maharolkar, Aruna P.; Khirade, P. W.; Murugkar, A. G.

2016-05-01

Present paper deals with study of physicochemical properties like viscosity, density and refractive index for the binary mixtures of ethanol and methanol over the entire concentration range were measured at 298.15 K. The experimental data further used to determine the excess properties viz. excess molar volume, excess viscosity, excess molar refraction. The values of excess properties further fitted with Redlich-Kister (R-K Fit) equation to calculate the binary coefficients and standard deviation. The resulting excess parameters are used to indicate the presence of intermolecular interactions and strength of intermolecular interactions between the molecules in the binary mixtures. Excess parameters indicate structure making factor in the mixture predominates in the system.

Molecular dynamics simulation of ZnO wurtzite phase under high and low pressures and temperatures

NASA Astrophysics Data System (ADS)

Chergui, Y.; Aouaroun, T.; Hadley, M. J.; Belkada, R.; Chemam, R.; Mekki, D. E.

2017-11-01

Isothermal and isobaric ensembles behaviours of ZnO wurtzite phase have been investigated, by parallel molecular dynamics method and using Buckingham potential, which contains long-range Coulomb, repulsive exponential, and attractive dispersion terms. To conduct our calculations, we have used dl_poly 4 software, under which the method is implemented. We have examined the influence of the temperature and pressure on molar volume in the ranges of 300-3000 K and 0-200 GPa. Isothermal-isobaric relationships, fluctuations, standard error, equilibrium time, molar volume and its variation versus time are predicted and analyzed. Our results are close to available experimental data and theoretical results.

Preparation and characterization of PEG-modified PCL nanoparticles for oxygen carrier: a new application of Fourier transform infrared spectroscopy for quantitative analysis of the hemoglobin in nanoparticles.

PubMed

Shan, Xiaoqian; Yuan, Yuan; Liu, Changsheng

2015-01-01

The influence of polyethylene glycol (PEG) molar ratio on the nanoparticles (NPs) properties is described herein. Especially, a facile and nondestructive determination route has been raised to quantify the hemoglobin (Hb) amounts in NPs via an internal standard FTIR method. The subsequent results indicated that, briefly, the PEG molar ratio did negligible influence on the size distribution of NPs, however, it did have great effect on the NPs zeta potential and hydrophilicity as well as the Hb loading amount. These findings highlight that the PEG density on the surface is a key parameter affecting the NPs properties.

Thermodynamic properties of 5(nitrophenyl) furan-2-carbaldehyde isomers.

PubMed

Dibrivnyi, Volodymyr; Sobechko, Iryna; Puniak, Marian; Horak, Yuriy; Obushak, Mykola; Van-Chin-Syan, Yuriy; Andriy, Marshalek; Velychkivska, Nadiia

2015-01-01

The aim of the current work was to determine thermo dynamical properties of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde. The temperature dependence of saturated vapor pressure of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde was determined by Knudsen's effusion method. The results are presented by the Clapeyron-Clausius equation in linear form, and via this form, the standard enthalpies, entropies and Gibbs energies of sublimation and evaporation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly by the corresponding standard molar combustion enthalpy, obtained using bomb calorimetry combustion. Determination of the thermodynamic properties for these compounds may contribute to solving practical problems pertaining optimization processes of their synthesis, purification and application and it will also provide a more thorough insight regarding the theoretical knowledge of their nature.Graphical abstract:Generalized structural formula of investigated compounds and their formation enthalpy determination scheme in the gaseous state.

Efficacy of Platelet-Rich Fibrin After Mandibular Third Molar Extraction: A Systematic Review and Meta-Analysis.

PubMed

Al-Hamed, Faez Saleh; Tawfik, Mohamed Abdel-Monem; Abdelfadil, Ehab; Al-Saleh, Mohammed A Q

2017-06-01

To assess the effect of platelet-rich fibrin (PRF) on the healing process of the alveolar socket after surgical extraction of the mandibular third molars. PubMed, the Cochrane Central Register of Controlled Trials, Scopus, and relevant journals were searched using a combination of specific keywords ("platelet-rich fibrin," "oral surgery," and "third molar"). The final search was conducted on November 2, 2015. Randomized controlled clinical trials, as well as controlled clinical trials, aimed at comparing the effect of PRF versus natural healing after extraction of mandibular third molars were included. Five randomized controlled trials and one controlled clinical trial were included. There were 335 extractions (168 with PRF and 167 controls) in 183 participants. Considerable heterogeneity in study characteristics, outcome variables, and estimated scales was observed. Positive results were generally recorded for pain, trismus, swelling, periodontal pocket depth, soft tissue healing, and incidence of localized osteitis, but not in all studies. However, no meta-analysis could be conducted for such variables because of the different measurement scales used. The qualitative and meta-analysis results showed no significant improvement in bone healing with PRF-treated sockets compared with the naturally healing sockets. Within the limitations of the available evidence, PRF seems to have no beneficial role in bone healing after extraction of the mandibular third molars. Future standardized randomized controlled clinical trials are required to estimate the effect of PRF on socket regeneration. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

An Ex Vivo Comparison of Digital Radiography, Cone Beam and Micro Computed Tomography in the Detection of the Number of Canals in the Mesiobuccal Roots of Maxillary Molars

PubMed Central

Domark, Jeffrey D.; Hatton, John F.; Benison, Roxanne P.; Hildebolt, Charles F.

2014-01-01

Introduction The purpose of this study was to compare digital periapical and cone beam computed tomography (CBCT) images to determine the number of canals in the mesiobuccal root (MB) of maxillary molars and to compare these counts to micro CT (μCT), which was also used to determine canal configuration. Methods Digital periapical (RVG 6100), CBCT (9000 3D) and μCT images (the reference standard) were obtained of 18 hemi-maxillas. With periapical and CBCT images, 2 endodontists independently counted the number of canals in each molar and repeated counts 2 weeks later. Teeth were extracted, scanned with μCT, and 2 additional endodontists, by consensus, determined the number and configuration of canals. The Friedman test was used to test for differences. Results In mesiobuccal roots, 2 canals were present in 100% (13/13) of maxillary first and 57% (8/14) second molars, and 69% (9/13) and 100% (8/8) of these exited as two or more foramina. There was no difference in canal counts for original and repeat reads by the two observers with periapicals (P = 0.06) and with CBCT (P = 0.88) and no difference when CBCT counts were compared with μCT counts (P = 0.52); however, when periapical counts were compared with μCT counts there was a significant difference (P = 0.04). Conclusions For cadaver maxillary molars, μCT canal counts were significantly different from digital periapical radiograph counts but not different from Carestream 9000 3D CBCT counts. PMID:23791260

Outcomes and stability in patients with anterior open bite and long anterior face height treated with temporary anchorage devices and a maxillary intrusion splint

PubMed Central

Scheffler, Nicole R.; Proffit, William R.; Phillips, Ceib

2015-01-01

Introduction Temporary skeletal anchorage devices now offer the possibility of closing anterior open bites and decreasing anterior face height by intruding maxillary posterior teeth, but data for treatment outcomes are lacking. This article presents outcomes and posttreatment changes for consecutive patients treated with a standardized technique. Methods The sample included 33 consecutive patients who had intrusion of maxillary posterior teeth with a maxillary occlusal splint and nickel-titanium coil springs to temporary anchorage devices in the zygomatic buttress area, buccal and apical to the maxillary molars. Of this group, 30 had adequate cephalograms available for the period of treatment, 27 had cephalograms including 1-year posttreatment, and 25 had cephalograms from 2 years or longer. Results During splint therapy, the mean molar intrusion was 2.3 mm. The mean decrease in anterior face height was 1.6 mm, less than expected because of a 0.6-mm mean eruption of the mandibular molars. During the postintrusion orthodontics, the mean change in maxillary molar position was a 0.2-mm extrusion, and there was a mean 0.5-mm increase in face height. Positive overbite was maintained in all patients, with a slight elongation (<2 mm) of the incisors contributing to this. During the 1 year of posttreatment retention, the mean changes were a further eruption of 0.5 mm of the maxillary molars, whereas the mandibular molars intruded by 0.6 mm, and there was a small decrease in anterior face height. Changes beyond 1 year posttreatment were small and attributable to growth rather than relapse in tooth positions. Conclusions Intrusion of the maxillary posterior teeth can give satisfactory correction of moderately severe anterior open bites, but 0.5 to 1.5 mm of reeruption of these teeth is likely to occur. Controlling the vertical position of the mandibular molars so that they do not erupt as the maxillary teeth are intruded is important in obtaining a decrease in face height. PMID:25439210

Piezoelectric Versus Conventional Rotary Techniques for Impacted Third Molar Extraction

PubMed Central

Jiang, Qian; Qiu, Yating; Yang, Chi; Yang, Jingyun; Chen, Minjie; Zhang, Zhiyuan

2015-01-01

Abstract Impacted third molars are frequently encountered in clinical work. Surgical removal of impacted third molars is often required to prevent clinical symptoms. Traditional rotary cutting instruments are potentially injurious, and piezosurgery, as a new osteotomy technique, has been introduced in oral and maxillofacial surgery. No consistent conclusion has been reached regarding whether this new technique is associated with fewer or less severe postoperative sequelae after third molar extraction. The aim of this study was to compare piezosurgery with rotary osteotomy techniques, with regard to surgery time and the severity of postoperative sequelae, including pain, swelling, and trismus. We conducted a systematic literature search in the Cochrane Library, PubMed, Embase, and Google Scholar. The eligibility criteria of this study included the following: the patients were clearly diagnosed as having impacted mandibular third molars; the patients underwent piezosurgery osteotomy, and in the control group rotary osteotomy techniques, for removing impacted third molars; the outcomes of interest include surgery time, trismus, swelling or pain; the studies are randomized controlled trials. We used random-effects models to calculate the difference in the outcomes, and the corresponding 95% confidence interval. We calculated the weighted mean difference if the trials used the same measurement, and a standardized mean difference if otherwise. A total of seven studies met the eligibility criteria and were included in our analysis. Compared with rotary osteotomy, patients undergoing piezosurgery experienced longer surgery time (mean difference 4.13 minutes, 95% confidence interval 2.75–5.52, P < 0.0001). Patients receiving the piezoelectric technique had less swelling at postoperative days 1, 3, 5, and 7 (all Ps ≤0.023). Additionally, there was a trend of less postoperative pain and trismus in the piezosurgery groups. The number of included randomized controlled trials and the sample size of each trial were relatively small, double blinding was not possible, and cost analysis was unavailable due to a lack of data. Our meta-analysis indicates that although patients undergoing piezosurgery experienced longer surgery time, they had less postoperative swelling, indicating that piezosurgery is a promising alternative technique for extraction of impacted third molars. PMID:26469902

Piezoelectric Versus Conventional Rotary Techniques for Impacted Third Molar Extraction: A Meta-analysis of Randomized Controlled Trials.

PubMed

Jiang, Qian; Qiu, Yating; Yang, Chi; Yang, Jingyun; Chen, Minjie; Zhang, Zhiyuan

2015-10-01

Impacted third molars are frequently encountered in clinical work. Surgical removal of impacted third molars is often required to prevent clinical symptoms. Traditional rotary cutting instruments are potentially injurious, and piezosurgery, as a new osteotomy technique, has been introduced in oral and maxillofacial surgery. No consistent conclusion has been reached regarding whether this new technique is associated with fewer or less severe postoperative sequelae after third molar extraction.The aim of this study was to compare piezosurgery with rotary osteotomy techniques, with regard to surgery time and the severity of postoperative sequelae, including pain, swelling, and trismus.We conducted a systematic literature search in the Cochrane Library, PubMed, Embase, and Google Scholar.The eligibility criteria of this study included the following: the patients were clearly diagnosed as having impacted mandibular third molars; the patients underwent piezosurgery osteotomy, and in the control group rotary osteotomy techniques, for removing impacted third molars; the outcomes of interest include surgery time, trismus, swelling or pain; the studies are randomized controlled trials.We used random-effects models to calculate the difference in the outcomes, and the corresponding 95% confidence interval. We calculated the weighted mean difference if the trials used the same measurement, and a standardized mean difference if otherwise.A total of seven studies met the eligibility criteria and were included in our analysis. Compared with rotary osteotomy, patients undergoing piezosurgery experienced longer surgery time (mean difference 4.13 minutes, 95% confidence interval 2.75-5.52, P < 0.0001). Patients receiving the piezoelectric technique had less swelling at postoperative days 1, 3, 5, and 7 (all Ps ≤0.023). Additionally, there was a trend of less postoperative pain and trismus in the piezosurgery groups.The number of included randomized controlled trials and the sample size of each trial were relatively small, double blinding was not possible, and cost analysis was unavailable due to a lack of data.Our meta-analysis indicates that although patients undergoing piezosurgery experienced longer surgery time, they had less postoperative swelling, indicating that piezosurgery is a promising alternative technique for extraction of impacted third molars.

Distal extension mandibular removable partial denture with implant support

PubMed Central

Bural, Canan; Buzbas, Begum; Ozatik, Sebnem; Bayraktar, Gulsen; Emes, Yusuf

2016-01-01

This case report describes the fabrication of a distal extension removable partial denture (RPD) of a 65-year-old man with implant support. Loss of fibroelasticity of the peripheral tissues and reduced mandibular vestibular sulcular depth due to a previous surgical resection and radiotherapy at the right side were the main clinical factors that created difficulty for denture retention and stability. The fabrication of a mandibular RPD supported by anterior teeth and two bilaterally placed implants in the molar area to convert from Kennedy Class 1 design to Kennedy Class 3 implant-bounded RPD is reported. Retention and stability of the denture were improved with implant support on the distal extension site of the RPD. The common clinical problems about distally extended RPDs are lack of retention and stability due to the movement around the rotational axis. Dental implant placement to the distal edentulous site minimizes the potential dislodgement of the RPD is popular. Implant-supported RPD can be suggested as an advantageous and cost-effective treatment option for the partially edentulous patients. PMID:28042277

Economic modeling of sealing primary molars using a "value of information" approach.

PubMed

Ney, J P; van der Goes, D N; Chi, D L

2014-09-01

The objective was to evaluate 2 primary molar sealant strategies for publicly insured children using an "expected value of perfect information" (EVPI) approach. We converted a 10,000-observation tooth-level cost-effectiveness simulation model comparing 2 primary molar sealant strategies - always seal (AS) and standard care (SC) - with a 1,250-observation child-level model. Costs per child per restoration or extraction averted were estimated. Opportunity losses under the AS strategy were determined for children for whom SC was the optimal choice. We determined the EVPI by multiplying mean opportunity losses by the projected incident population of publicly insured 3-year-olds in the US over 10 years with costs discounted at 2%. All analyses were conducted under assumptions of high and low intrachild correlations between at-risk teeth. The AS strategy cost $43.68 over SC (95% CI: -$5.50, $92.86) per child per restoration or extraction averted under the high intrachild correlation assumption and $15.54 (95% CI $7.86, $23.20) under the low intrachild correlation. Under high intrachild correlation, mean opportunity losses were $80.28 (95% CI: $76.39, $84.17) per child, and AS was the optimal strategy in 31% of children. Under low correlation, mean opportunity losses were $14.61 (95% CI: $12.20, $17.68) and AS was the optimal strategy in 87% of children. The EVPI was calculated at $530,813,740 and $96,578,389 (for high and low intrachild correlation, respectively), for a projected total incident population of 8,059,712 children. On average, always sealing primary molars is more effective than standard care, but widespread implementation of this preventive approach among publicly insured children would result in large opportunity losses. Additional research is needed to identify the subgroups of publicly insured children who would benefit the most from this effective and potentially cost-saving public health intervention. © International & American Associations for Dental Research.

Methodological considerations on descriptive studies of induced periodontal diseases in rats.

PubMed

Galvão, Mariane Ponzio; Chapper, Ana; Rösing, Cassiano Kuchenbecker; Ferreira, Maria Beatriz; de Souza, Maria Antonieta

2003-01-01

The aim of this study was to show the technique and the methodological approach used in describing histological characteristics of induced periodontal disease in rats. To reach that inflammatory process, periodontal disease was induced by ligature, with or without sucrose-rich diet. Twenty-four female adult (60 days old) Wistar rats were divided in four groups: Group 1, or control (which received standard diet), Group 2 (which received ligature around the upper second molars and a standard diet), Group 3 (which received a sucrose-rich diet), and Group 4 (which received ligature around the upper second molars and a sucrose-rich diet). The animals were followed for a period of 30 days, after which they were sacrificed. The upper second molars were removed, processed, and the histological characteristics were analyzed by a descriptive dichotomous method. The results were analyzed by the Fisher's exact test (significance level of 95%) and by a residual test, which showed the relation between groups and histological characteristics. The animals which received ligature (Groups 2 and 4) showed histological characteristics related with periodontitis, whilst the animals without ligatures showed no periodontal destruction. This was shown by a distribution of these groups in extremes of a graphic representation. The use of a ligature, as done in this study, was able to promote a chronic inflammatory process in the periodontium of rats, regardless of the adopted diet. The correspondence factorial analysis was capable of showing these characteristics, being one more tool to be used in histological research.

Cul3-mediated Nrf2 ubiquitination and antioxidant response element (ARE) activation are dependent on the partial molar volume at position 151 of Keap1.

PubMed

Eggler, Aimee L; Small, Evan; Hannink, Mark; Mesecar, Andrew D

2009-07-29

Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor that activates transcription of a battery of cytoprotective genes by binding to the ARE (antioxidant response element). Nrf2 is repressed by the cysteine-rich Keap1 (kelch-like ECH-associated protein 1) protein, which targets Nrf2 for ubiquitination and subsequent degradation by a Cul3 (cullin 3)-mediated ubiquitination complex. We find that modification of Cys(151) of human Keap1, by mutation to a tryptophan, relieves the repression by Keap1 and allows activation of the ARE by Nrf2. The Keap1 C151W substitution has a decreased affinity for Cul3, and can no longer serve to target Nrf2 for ubiquitination, though it retains its affinity for Nrf2. A series of 12 mutant Keap1 proteins, each containing a different residue at position 151, was constructed to explore the chemistry required for this effect. The series reveals that the extent to which Keap1 loses the ability to target Nrf2 for degradation, and hence the ability to repress ARE activation, correlates well with the partial molar volume of the residue. Other physico-chemical properties do not appear to contribute significantly to the effect. Based on this finding, a structural model is proposed whereby large residues at position 151 cause steric clashes that lead to alteration of the Keap1-Cul3 interaction. This model has significant implications for how electrophiles which modify Cys(151), disrupt the repressive function of Keap1.

Evaluation of stress patterns produced by implant-retained overdentures and implant-retained fixed partial denture.

PubMed

Mazaro, José Vitor Quinelli; Filho, Humberto Gennari; Vedovatto, Eduardo; Pellizzer, Eduardo Piza; Rezende, Maria Cristina Rosifini Alves; Zavanelli, Adriana Cristina

2011-11-01

The purposes of this study were to photoelastically measure the biomechanical behavior of 4 implants retaining different cantilevered bar mandibular overdenture designs and to compare a fixed partial denture (FPD). A photoelastic model of a human edentulous mandible was fabricated, which contained 4 screw-type implants (3.75 × 10 mm) embedded in the parasymphyseal area. An FPD and 3 overdenture designs with the following attachments were evaluated: 3 plastic Hader clips, 1 Hader clip with 2 posterior resilient cap attachments, and 3 ball/O-ring attachments. Vertical occlusal forces of 100 N were applied between the central incisor and unilaterally to the right and left second premolars and second molars. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. The results showed that the anterior loading, the overdenture with 3 plastic Hader clips, displayed the largest stress concentration at the medium implant. With premolar loading, the FPD and overdenture with 3 plastic Hader clips displayed the highest stresses to the ipsilateral terminal implant. With molar loading, the overdenture with 3 ball/O-ring attachments displayed the most uniform stress distribution in the posterior edentulous ridge, with less overloading in the terminal implant. It was concluded that vertical forces applied to the bar-clip overdenture and FPD created immediate stress patterns of greater magnitude and concentration on the ipsilateral implants, whereas the ball/O-ring attachments transferred minimal stress to the implants. The increased cantilever in the FPD caused the highest stresses to the terminal implant.

Fracture Strength of Three-Unit Implant Supported Fixed Partial Dentures with Excessive Crown Height Fabricated from Different Materials.

PubMed

Nazari, Vahideh; Ghodsi, Safoura; Alikhasi, Marzieh; Sahebi, Majid; Shamshiri, Ahmad Reza

2016-11-01

Fracture strength is an important factor influencing the clinical long-term success of implant-supported prostheses especially in high stress situations like excessive crown height space (CHS). The purpose of this study was to compare the fracture strength of implant-supported fixed partial dentures (FPDs) with excessive crown height, fabricated from three different materials. Two implants with corresponding abutments were mounted in a metal model that simulated mandibular second premolar and second molar. Thirty 3-unit frameworks with supportive anatomical design were fabricated using zirconia, nickel-chromium alloy (Ni-Cr), and polyetheretherketone (PEEK) (n=10). After veneering, the CHS was equal to 15mm. Then; samples were axially loaded on the center of pontics until fracture in a universal testing machine at a crosshead speed of 0.5 mm/minute. The failure load data were analyzed by one-way ANOVA and Games-Howell tests at significance level of 0.05. The mean failure loads for zirconia, Ni-Cr and PEEK restorations were 2086±362N, 5591±1200N and 1430±262N, respectively. There were significant differences in the mean failure loads of the three groups (P<0.001). The fracture modes in zirconia, metal ceramic and PEEK restorations were cohesive, mixed and adhesive type, respectively. According to the findings of this study, all implant supported three-unit FPDs fabricated of zirconia, metal ceramic and PEEK materials are capable to withstand bite force (even para-functions) in the molar region with excessive CHS.

Aspartic acid racemization in dentin of the third molar for age estimation of the Chaoshan population in South China.

PubMed

Chen, Shisheng; Lv, Yanyi; Wang, Dian; Yu, Xiaojun

2016-09-01

Aspartic acid racemization in teeth has been increasingly used to estimate chronological age with a considerably high accuracy in forensic practice. The Chaoshan population in South China is relatively isolated in geography, and has specific lifestyle and dietary inhibits. It is still unknown whether this method is suitable for this population. The aim of this study was to analyze the relationship between chronological age and the d/l aspartic acid ratio in dentin in the third molar tooth of the Chaoshan population. Fifty-eight non-carious third molar teeth (31 mandibles and 27 maxillae), from 58 living individuals of known age (24 males and 34 females), were retrieved. Dentin was extracted from these teeth. The d- and l-aspartic acids in dentins were separated and detected by high performance liquid chromatography (HPLC). Linear regression was performed between the d/l aspartic acid ratio of dentins and chronological age. Results showed that the correlation coefficient (r) was 0.969, and the mean absolute error (MAE) was 2.19 years, its standard deviation (SD) was ±1.53 years, indicating excellent correlation. There was no significant difference in racemization rates of dentin between sexes (P=0.113, F=2.6), or between mandibles and maxillae (P=0.964, F=0.000). Results indicate that the ratio of the d and l forms of aspartic acid of dentins, in the third molar, is closely correlated with chronological age, special lifestyle do no obviously affect the accuracy of the age estimations by aspartic acid racemization of the dentin in the third molar and that aspartic acid racemization in the third molar dentin can be used as an accurate method to estimate chronological age in the Chaoshan population in South China. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Measure Of Frequency Of Alveolar Osteitis Using Two Different Methods Of Osteotomy In Mandibular Third Molar Impactions: A Double-Blind Randomized Clinical Trial.

PubMed

Rashid, Hina; Hussain, Azmina; Sheikh, Abdul Hafeez; Azam, Kehkishan; Malik, Sofia; Amin, Muhammad

2018-01-01

Dento-alveolar surgical procedures involving third molar teeth are the most common surgical procedure in the field of surgery. The objective of this research was to analyse the impact of surgery on the incidence of alveolar osteitis after surgical removal of mandibular third molar and to compare two different bone cutting methods following impacted mandibular third molar surgery.. This double blinded randomized clinical trial was executed at the OPD of Department of Oral and Maxillofacial Surgery, Dow University of Health Sciences, Karachi. The study duration was four months. It was conducted on 60 patients needing unilateral mandibular third molar impaction removal. Patients were randomized to two groups (i.e., physio dispenser group and slow speed handpiece group) before surgery. The surgical procedure was performed under local anaesthesia by using standardized cross infection protocol. The frequency of alveolar osteitis was evaluated on thirdday postoperatively. Alveolar osteitis was diagnosed and confirmed by patient's history and clinical evaluation. Post-operative sequelae were observed and recorded objectively. Out of 60 patients', five patients experienced alveolar osteitis, and the incidence rate was 8.3%. A significant pvalue of 0.000 was calculated using binomial test for comparison of alveolar osteitis among both groups. Inter-examiner reliability was assessed by kappa and good (62%) agreement, which was found among the examiners, who diagnosed alveolar osteitis clinically. Post-operative sequelae were insignificant in slow speed hand piece group. It was observed that alveolar osteitis was reported in physio-dispenser group; similarly, post-operative complications were also more in this group as compared with slow speed-hand piece group. No surgical complications were observed in slow speed-hand piece group suggesting slow speed hand piece mode of osteotomy to be safer for third molar extraction as compared with physio-dispenser.

Thermodynamics of Sodium Dodecyl Sulfate (SDS) Micellization: An Undergraduate Laboratory Experiment

ERIC Educational Resources Information Center

Marcolongo, Juan P.; Mirenda, Martin

2011-01-01

An undergraduate laboratory experiment is presented that allows a thermodynamic characterization of micelle formation of sodium dodecyl sulfate (SDS) in aqueous solutions. The critical micelle concentration (CMC) and the degree of micelle ionization (alpha) are obtained at different temperatures by conductimetry. The molar standard free energy…

Importance of sulfide interaction with iron as regulator of the microbial community in biogas reactors and its effect on methanogenesis, volatile fatty acids turnover, and syntrophic long-chain fatty acids degradation.

PubMed

Shakeri Yekta, Sepehr; Ziels, Ryan M; Björn, Annika; Skyllberg, Ulf; Ejlertsson, Jörgen; Karlsson, Anna; Svedlund, Matilda; Willén, Magnus; Svensson, Bo H

2017-05-01

The inhibitory effects of sulfide on microbial processes during anaerobic digestion have been widely addressed. However, other effects of sulfide are less explored, given that sulfide is a potential sulfur source for microorganisms and its high reactivity triggers a suit of abiotic reactions. We demonstrated that sulfide interaction with Fe regulates the dynamics and activities of microbial community during anaerobic digestion. This was manifested by the S:Fe molar ratio, whose increase adversely influenced the acetoclastic methanogens, Methanosaeta, and turnover of acetate. Dynamics of hydrogenotrophic methanogens, Methanoculleus and Methanobrevibacter, were presumably influenced by sulfide-induced changes in the partial pressure of hydrogen. Interestingly, conversion of the long-chain fatty acid (LCFA), oleate, to methane was enhanced together with the abundance of LCFA-degrading, β-oxidizing Syntrophomonas at an elevated S:Fe molar ratio. The results suggested that sulfur chemical speciation is a controlling factor for microbial community functions in anaerobic digestion processes. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effects of ketoprofen and diclofenac potassium on blood coagulation tests after removal of third molars.

PubMed

Naclério-Homem, Maria da Graça; Deboni, Maria Christina Zindel; Rapoport, Abrăo; Chin, Veronica Kei Len

2009-04-01

Nonsteroidal anti-inflammatory drugs inhibit platelet aggregation and increase bleeding time; however, they are required to control pain and swelling following dental surgery. The objective of this study was to evaluate possible changes on blood coagulation tests by using ketoprofen and diclofenac potassium after removal of mandibular third molars. Fifty-one subjects between 16 and 30 years old, with no history of gastrointestinal disorders or allergy to anti-inflammatory components, were randomly assigned to 2 groups: 27 patients received 50 mg of ketoprofen, and 24 patients received 25 mg of diclofenac potassium. Subjects started the oral medication 2 hours before surgery and continued taking it every 8 hours for 5 days. Blood samples were collected preoperatively and on the final day of the drug regime to evaluate prothrombin time, activated partial thromboplastin time, clot retraction, and platelet count. Student t test for matched pairs did not show a significant difference between pre- and posttreatment variables for both anti-inflammatory drugs. These results suggest that the safety of ketoprofen and diclofenac potassium is comparable to their anticoagulation effect.

Salt potentiates methylamine counteraction system to offset the deleterious effects of urea on protein stability and function.

PubMed

Rahman, Safikur; Rehman, Md Tabish; Singh, Laishram R; Warepam, Marina; Ahmad, Faizan; Dar, Tanveer Ali

2015-01-01

Cellular methylamines are osmolytes (low molecular weight organic compounds) believed to offset the urea's harmful effects on the stability and function of proteins in mammalian kidney and marine invertebrates. Although urea and methylamines are found at 2:1 molar ratio in tissues, their opposing effects on protein structure and function have been questioned on several grounds including failure to counteraction or partial counteraction. Here we investigated the possible involvement of cellular salt, NaCl, in urea-methylamine counteraction on protein stability and function. We found that NaCl mediates methylamine counteracting system from no or partial counteraction to complete counteraction of urea's effect on protein stability and function. These conclusions were drawn from the systematic thermodynamic stability and functional activity measurements of lysozyme and RNase-A. Our results revealed that salts might be involved in protein interaction with charged osmolytes and hence in the urea-methylamine counteraction.

Combining wrist age and third molars in forensic age estimation: how to calculate the joint age estimate and its error rate in age diagnostics.

PubMed

Gelbrich, Bianca; Frerking, Carolin; Weiss, Sandra; Schwerdt, Sebastian; Stellzig-Eisenhauer, Angelika; Tausche, Eve; Gelbrich, Götz

2015-01-01

Forensic age estimation in living adolescents is based on several methods, e.g. the assessment of skeletal and dental maturation. Combination of several methods is mandatory, since age estimates from a single method are too imprecise due to biological variability. The correlation of the errors of the methods being combined must be known to calculate the precision of combined age estimates. To examine the correlation of the errors of the hand and the third molar method and to demonstrate how to calculate the combined age estimate. Clinical routine radiographs of the hand and dental panoramic images of 383 patients (aged 7.8-19.1 years, 56% female) were assessed. Lack of correlation (r = -0.024, 95% CI = -0.124 to + 0.076, p = 0.64) allows calculating the combined age estimate as the weighted average of the estimates from hand bones and third molars. Combination improved the standard deviations of errors (hand = 0.97, teeth = 1.35 years) to 0.79 years. Uncorrelated errors of the age estimates obtained from both methods allow straightforward determination of the common estimate and its variance. This is also possible when reference data for the hand and the third molar method are established independently from each other, using different samples.

Handpiece speed and postoperative outcomes in third molar surgery.

PubMed

Campbell, John H; Murray, R Anthony

2004-01-01

This study was performed to assess surgical outcomes when externally irrigated slow-speed surgical handpieces (30,000 rpm) were compared to externally irrigated high-speed handpieces (90,000 rpm) in the removal of impacted lower third molar teeth. One hundred patients with bilater ally impacted third molar s were enrolled in the study; 53 remained to completion. Each patient served as his/her own control. The experimental side was treated using a 30,000 rpm electric rotary drill incorporating irrigation, while the control side was treated using the same drill system, but with a 90,000 rpm handpiece. Drill speeds used were alternated between the right and left sides of patients to avoid bias introduced by the dominant hand of the surgeon. Patients were blinded to drill speed, and were asked to complete a standardized pain/swelling questionnaire for seven days immediately following surgery. Data was analyzed to determine differences in pain, swelling, and complications in relation to the drill type used. No statistically significant differences were found in degree of pain, swelling, or complications when the slower drill was compared to the high-speed instrument. The study suggests that there is no difference in postoperative outcome when impacted third molar teeth are removed with either slow- or high-speed instrumentation, and that the choice of the drill type should be determined solely by the preference of the operator.

Purification of biodiesel by choline chloride based deep eutectic solvent

NASA Astrophysics Data System (ADS)

Niawanti, Helda; Zullaikah, Siti; Rachimoellah, M.

2017-05-01

Purification is a crucial step in biodiesel production to meet the biodiesel standard. This study purified biodiesel using choline chloride based deep eutectic solvent (DES). DES was used to reduce unreacted oil and unsaponifiable matter in rice bran oil based biodiesel. The objective of this work was to study the effect of extraction time using DES on the content and yield of fatty acid methyl ester (FAME). Rice bran used in this work contains 16.49 % of oil with initial free fatty acids (FFA) of 44.75 %. Acid catalyzed methanolysis was employed to convert rice bran oil (RBO) into biodiesel under following operation conditions: T = 60 °C, t = 8 h, molar ratio of oil to methanol = 1/10, H2SO4 = 1% w/w of oil. Rice bran oil based biodiesel obtained contain 89.05 % of FAME with very low FFA content (0.05 %). DES was made from a mixture of choline chloride and ethylene glycol with molar ratio of 1/2. Molar ratio of crude biodiesel to DES were 1/2 and 1/4. Extraction time was varied from 15 minutes to 240 minutes at 30 °C. The highest FAME content was obtained after purification for 240 min. at molar ratio crude biodiesel to DES 1/4 was 96.60 %. This work shows that DES has potential to purify biodiesel from non-edible raw material, such as RBO.

Problems of comparing blood glucose molality and molarity determined with an Omni, an EML 105 and an Ebio analyser.

PubMed

Haeckel, Rainer; Hänecke, Petra

2003-07-01

The comparability between glucose concentrations measured in various sample systems is still a matter of debate. Decision limits are usually determined in venous plasma and then converted to either blood or to the aqueous compartment (activity). The conversion factors recommended have not yet been generally accepted. In the present study, glucose concentrations were determined in blood and plasma with an Ebio analyser (molarity) and in the aqueous compartment with both an EML 105 and an Omni (molality). All analytical results were referred to the same aqueous standard solution. The Ebio results agreed with reference method values in control materials. Concentrations determined in the various sample systems from patients (molarity) correlated well with the molality values measured either with the EML or the Omni. However, the mean values of the EML were not consistent with those derived theoretically by considering the different water content. With the Omni, only molality values in whole blood appeared plausible, but not in plasma, although the two sample systems should provide identical molality values. The EML results were almost identical in whole blood and plasma. Theoretically, glucose molality would be the ideal diagnostic quantity. However, no diagnostic advantage of molality determined in whole blood with the Omni vs. molarity values could be detected in a group of 40 non-diabetic and 27 diabetic subjects.

Analgesic efficacy of lysine clonixinate plus tramadol versus tramadol in multiple doses following impacted third molar surgery.

PubMed

Perez-Urizar, J; Martínez-Rider, R; Torres-Roque, I; Garrocho-Rangel, A; Pozos-Guillen, A

2014-03-01

This study compared the analgesic and anti-inflammatory efficacy, trismus control, and tolerability of the combination of lysine clonixinate and tramadol (LCT) versus tramadol (T) alone after surgical removal of impacted mandibular third molars. This study was a double-blind, randomized clinical trial, including two study groups of 20 patients each, who exhibited acute pain subsequent to surgical extraction of two mandibular third molars. Pain intensity was quantified over a 96-h period using a visual analogue scale and a 5-point verbal rating scale. Secondary indicators of analgesic and anti-inflammatory efficacy, trismus control, and tolerability were determined. Patients administered LCT exhibited better therapeutic effects that those administered T. Fifty percent of patients in the LCT group rated this therapy as 'excellent analgesia' compared with only 10% in the T group. The onset of the analgesic effect of LCT was significantly faster, without any therapeutic failures. There were no significant differences between the groups with regard to anti-inflammatory effect or trismus. The results of this study suggest that the postsurgical analgesic efficacy of LCT in combination (LC 125 mg + T 25 mg) is superior to that obtained with T alone, administered at the standard dose of 50 mg, for up to 96 h after the extraction of both impacted mandibular third molars. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Nothing new under the heavens: MIH in the past?

PubMed

Ogden, A R; Pinhasi, R; White, W J

2008-12-01

This was to study an archaeological population of subadult teeth in 17th and 18th century skeletal material from a London (England) cemetery for enamel defects including molar-incisor-hypomineralisation (MIH). Dentitions of 45 sub-adults were examined using standard macroscopic methods and systematically recorded. A total of 557 teeth were examined with a *5 lens and photographed. Ages of the individuals were estimated from their dental crown and root development stages and not from charts that combine tooth eruption with development stages. The dental age of the individual and the approximate age of onset of enamel defects was then calculated on the basis of the chronological sequence of incremental deposition and calcification of the enamel matrix. Affected enamel was graded macroscopically as: - Mild: <30% of the tooth's enamel surface area visibly disrupted (this encompasses the entire range reported in most other studies), Moderate: 31-49% of the tooth's enamel surface area visibly disrupted and Severe: >50% of the tooth's enamel surface area visibly disrupted. Of the total number of individuals 41 (93.2%) showed signs of enamel developmental dysplasia or MIH, 28 of them showing moderate or severe lesions of molars, primary or permanent (63.6% of the sample). Incisors and canines, though surviving much less often, showed episodes of linear hypoplasia. The extensive lesions seen on many of the molars displayed cuspal enamel hypoplasia (CEH). Many of these teeth also exhibited Molar Incisal Hypomineralisation (MIH).

Laser vs bur for bone cutting in impacted mandibular third molar surgery: A randomized controlled trial.

PubMed

Passi, Deepak; Pal, Uma Shankar; Mohammad, Shadab; Singh, Rakesh Kumar; Mehrotra, Divya; Singh, Geeta; Kumar, Manoj; Chellappa, Arul A L; Gupta, Chandan

2013-01-01

The aim of this study was to assess the feasibility of Er: YAG laser in bone cutting for removal of impacted lower third molar teeth and compare its outcomes with that of surgical bur. The study comprised 40 subjects requiring removal of impacted mandibular third molar, randomly categorized into two equal groups of 20 each, who had their impacted third molar removed either using Er: YAG laser or surgical bur as per their group, using standard methodology of extraction of impacted teeth. Clinical parameters like pain, bleeding, time taken for bone cutting, postoperative swelling, trismus, wound healing and complications were compared for both groups. Clinical parameters like pain, bleeding and swelling were lower in laser group than bur group, although the difference was statistically not significant. However, postoperative swelling showed significant difference in the two groups. Laser group required almost double the time taken for bone cutting with bur. Trismus persisted for a longer period in laser group. Wound healing and complications were assessed clinically and there was no significant difference in both the groups. Based on the results of our study, the possibility of bone cutting using lasers is pursued, the osteotomy is easily performed and the technique is better suited to minimally invasive surgical procedures. The use of Er: YAG laser may be considered as an alternative tool to surgical bur, specially in anxious patients.

The Anesthetic Efficacy of Articaine and Lidocaine in Equivalent Doses as Buccal and Non-Palatal Infiltration for Maxillary Molar Extraction: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial.

PubMed

Majid, Omer Waleed; Ahmed, Aws Mahmood

2018-04-01

The purpose of the present study was to evaluate the anesthetic adequacy of 4% articaine 1.8 mL versus 2% lidocaine 3.6 mL without palatal injection compared with the standard technique for the extraction of maxillary molar teeth. This randomized, double-blinded, placebo-controlled clinical trial included patients requiring extraction of 1 maxillary molar under local anesthesia. Patients were randomly distributed into 1 of 3 groups: group A received 4% articaine 1.8 mL as a buccal injection and 0.2 mL as a palatal injection, group B received 4% articaine 1.8 mL plus normal saline 0.2 mL as a palatal injection, and group C received 2% lidocaine 3.6 mL plus normal saline 0.2 mL as a palatal injection. Pain was measured during injection, 8 minutes afterward, and during extraction using a visual analog scale. Initial palatal anesthesia and patients' satisfaction were measured using a 5-score verbal rating scale. Statistical analyses included descriptive statistics, analysis of variance, and Pearson χ 2 test. Differences with a P value less than .05 were considered significant. Eighty-four patients were included in the study. The average pain of injection was comparable among all study groups (P = .933). Pain during extraction in the articaine group was significantly less than that experienced in the placebo groups (P < .001), although the differences between placebo groups were insignificant. Satisfaction scores were significantly higher in the articaine group compared with the placebo groups (P < .001), with comparable results between placebo groups. Although the anesthetic effects of single placebo-controlled buccal injections of 4% articaine and 2% lidocaine were comparable, the level of anesthetic adequacy was statistically less than that achieved by 4% articaine given by the standard technique. These results do not justify the buccal and non-palatal infiltration of articaine or lidocaine as an effective alternative to the standard technique in the extraction of maxillary molar teeth. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Biofuel production from palm oil with supercritical alcohols: effects of the alcohol to oil molar ratios on the biofuel chemical composition and properties.

PubMed

Sawangkeaw, Ruengwit; Teeravitud, Sunsanee; Bunyakiat, Kunchana; Ngamprasertsith, Somkiat

2011-11-01

Biofuel production from palm oil with supercritical methanol (SCM) and supercritical ethanol (SCE) at 400 °C and 15 MPa were evaluated. At the optimal alcohol to oil molar ratios of 12:1 and 18:1 for the SCM and SCE processes, respectively, the biofuel samples were synthesized in a 1.2-L reactor and the resulting biofuel was analyzed for the key properties including those for the diesel and biodiesel standard specifications. Biofuel samples derived from both the SCM and SCE processes could be used as an alternative fuel after slight improvement in their acid value and free glycerol content. The remarkable advantages of this novel process were: the additional fuel yield of approximately of 5% and 10% for SCM and SCE, respectively; the lower energy consumption for alcohol preheating, pumping and recovering than the biodiesel production with supercritical alcohols that use a high alcohol to oil molar ratio of 42:1. Copyright © 2011 Elsevier Ltd. All rights reserved.

Structural and optical properties of Bi2O3-B2O3-CdO-Na2O glass system for gamma ray shielding applications

NASA Astrophysics Data System (ADS)

Dogra, Mridula; Singh, K. J.; Kaur, Kulwinder

2018-05-01

Quaternary system of the composition (0.15+x) Bi2O3-(0.55-x) B2O3-0.15CdO-0.15Na2O (where x=0, 0.1, 0.3 and 0.5 mole fraction) has been synthesized using melt-quenching technique. Gamma ray shielding properties are measured in terms of mass attenuation coefficient and half value layer at photon energies 662, 1173 and 1332 keV. These parameters are compared with standard nuclear radiation shielding `barite and ferrite' concretes. The results reflect better radiation shielding properties as compared to barite and ferrite concretes. Effective atomic number is calculated at photon energies 662 and 1173 keV. Density, molar volume and XRD studies are analyzed to know physical and structural properties of the glass system. Optical band gap, refractive index and molar refraction are calculated from UV-Visible measurements. Decrease in optical band gap and increase in molar refraction have been observed indicating the increase of non-bridging oxygens in the structure.

The Performance of ICDAS-II Using Low-Powered Magnification with Light-Emitting Diode Headlight and Alternating Current Impedance Spectroscopy Device for Detection of Occlusal Caries on Primary Molars.

PubMed

Ari, Timucin; Ari, Nilgun

2013-01-01

Early detection of occlusal caries in children is challenging for the dentists, because of the morphology of pit and fissures. The aim of this study was to compare in vitro the diagnostic performance of low-powered magnification with light-emitting diode headlight (LPMLED) using ICDAS-II criteria and AC Impedance Spectroscopy (ACIS) device, on occlusal surfaces of primary molars. The occlusal surfaces of 18 extracted primary molars were examined blindly by two examiners. The teeth were sectioned and examined under light microscopy using Downer's histological criteria as gold standard. Good to excellent inter- and intraexaminer reproducibility, higher sensitivity, specificity, and AUC values were achieved by LPMLED at D1 threshold. Also the relationship between histology and LPMLED was statistically significant. In conclusion visual aids have the potential to improve the performance of early caries detection and clinical diagnostics in children. Despite its potential, ACIS device should be considered as an adjunct method in detecting caries on primary teeth.

Characterization of the molar mass distribution of macromolecules in beer for different mashing processes using asymmetric flow field-flow fractionation (AF4) coupled with multiple detectors.

PubMed

Choi, Jaeyeong; Zielke, Claudia; Nilsson, Lars; Lee, Seungho

2017-07-01

The macromolecular composition of beer is largely determined by the brewing and the mashing process. It is known that the physico-chemical properties of proteinaceous and polysaccharide molecules are closely related to the mechanism of foam stability. Three types of "American pale ale" style beer were prepared using different mashing protocols. The foam stability of the beers was assessed using the Derek Rudin standard method. Asymmetric flow field-flow fractionation (AF4) in combination with ultraviolet (UV), multiangle light scattering (MALS) and differential refractive index (dRI) detectors was used to separate the macromolecules present in the beers and the molar mass (M) and molar mass distributions (MD) were determined. Macromolecular components were identified by enzymatic treatments with β-glucanase and proteinase K. The MD of β-glucan ranged from 10 6 to 10 8  g/mol. In addition, correlation between the beer's composition and foam stability was investigated (increased concentration of protein and β-glucan was associated with increased foam stability).

The Effect of Prism Orientation in the Indentation Testing of Human Molar Enamel

PubMed Central

Braly, A.; Darnell, L.A.; Mann, A.B.; Teaford, M.F.; Weihs, T.P.

2007-01-01

Recent nanoindentation studies have demonstrated that the hardness and Young's modulus of human molar enamel decreases by more than 50% on moving from the occlusal surface to the dentin-enamel junction on cross-sectional samples. Possible sources of these variations are changes in local chemistry, microstructure, and prism orientation. This study investigates the latter source by performing nanoindentation tests at two different orientations relative to the hydroxyapatite prisms: parallel and perpendicular. A single sample volume was tested in order to maintain a constant chemistry and microstructure. The resulting data show very small differences between the two orientations for both hardness and Young's modulus. The 1.5 to 3.0% difference is significantly less than the standard deviations found within the data set. Thus, the variations in hardness and Young's modulus on cross-sectional samples of human molar are attributed to changes in local chemistry (varying levels of mineralization, organic matter, and water content) and changes in microstructure (varying volume fractions of inorganic crystals and organic matrix). The impact of prism orientation on mechanical properties measured by nanoindentation appears to be minimal. PMID:17449008

Microwave dielectric study of polar liquids at 298 K

NASA Astrophysics Data System (ADS)

Maharolkar, Aruna P.; Murugkar, A.; Khirade, P. W.

2018-05-01

Present paper deals with study of microwave dielectric properties like dielectric constant, viscosity, density and refractive index for the binary mixtures of Dimethylsulphoxide (DMSO) and Methanol over the entire concentration range were measured at 298K. The experimental data further used to determine the excess properties viz. excess static dielectric constant, excess molar volume, excess viscosity& derived properties viz. molar refraction&Bruggman factor. The values of excess properties further fitted with Redlich-Kister (R-K Fit) equation to calculate the binary coefficients and standard deviation. The resulting excess parameters are used to indicate the presence of intermolecular interactions and strength of intermolecular interactions between the molecules in the binary mixtures. Excess parameters indicate structure breaking factor in the mixture predominates in the system.

Principle of two-dimensional characterization of copolymers.

PubMed

Weidner, Steffen; Falkenhagen, Jana; Krueger, Ralph-Peter; Just, Ulrich

2007-07-01

Two-dimensional polymer characterization is used for a simultaneous analysis of molar masses and chemical heterogeneities (e.g., end groups, copolymer composition, etc.). This principle is based on coupling of two different chromatographic modes. Liquid adsorption chromatography at critical conditions (LACCC) is applied for a separation according to the chemical heterogeneity, whereas in the second-dimension fractions are analyzed with regard to their molar mass distribution by means of size exclusion chromatography (SEC). Because appropriate standards for a calibration of the SEC are seldom available, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was used to substitute the SEC. The LACCC-MALDI MS coupling enables acquiring additional structural information on copolymer composition, which can considerably enhance the performance of this coupled method.

Is Inferior Alveolar Nerve Block Sufficient for Routine Dental Treatment in 4- to 6-year-old Children?

PubMed

Pourkazemi, Maryam; Erfanparast, Leila; Sheykhgermchi, Sanaz; Ghanizadeh, Milad

2017-01-01

Pain control is one of the most important aspects of behavior management in children. The most common way to achieve pain control is by using local anesthetics (LA). Many studies describe that the buccal nerve innervates the buccal gingiva and mucosa of the mandible for a variable extent from the vicinity of the lower third molar to the lower canine. Regarding the importance of appropriate and complete LA in child-behavior control, in this study, we examined the frequency of buccal gingiva anesthesia of primary mandibular molars and canine after inferior alveolar nerve block injection in 4- to 6-year-old children. In this descriptive cross-sectional study, 220 4- to 6-year-old children were randomly selected and entered into the study. Inferior alveolar nerve block was injected with the same method and standards for all children, and after ensuring the success of block injection, anesthesia of buccal mucosa of primary molars and canine was examined by stick test and reaction of child using sound, eye, motor (SEM) scale. The data from the study were analyzed using descriptive statistics and statistical software Statistical Package for the Social Sciences (SPSS) version 21. The area that was the highest nonanesthetized was recorded as in the distobuccal of the second primary molars. The area of the lowest nonanesthesia was also reported in the gingiva of primary canine tooth. According to this study, in 15 to 30% of cases, after inferior alveolar nerve block injection, the primary mandibular molars' buccal mucosa is not anesthetized. How to cite this article: Pourkazemi M, Erfanparast L, Sheykhgermchi S, Ghanizadeh M. Is Inferior Alveolar Nerve Block Sufficient for Routine Dental Treatment in 4- to 6-year-old Children? Int J Clin Pediatr Dent 2017;10(4):369-372.

Does the piezoelectric surgical technique produce fewer postoperative sequelae after lower third molar surgery than conventional rotary instruments? A systematic review and meta analysis.

PubMed

Al-Moraissi, E A; Elmansi, Y A; Al-Sharaee, Y A; Alrmali, A E; Alkhutari, A S

2016-03-01

A systematic review and meta-analysis was conducted to answer the clinical question "Does the piezoelectric surgical technique produce fewer postoperative sequelae after lower third molar surgery than conventional rotary instruments?" A systematic and electronic search of several databases with specific key words, a reference search, and a manual search were performed from respective dates of inception through November 2014. The inclusion criteria were clinical human studies, including randomized controlled trials (RCTs), controlled clinical trials (CCTs), and retrospective studies, with the aim of comparing the piezoelectric surgical osteotomy technique to the standard rotary instrument technique in lower third molar surgery. Postoperative sequelae (oedema, trismus, and pain), the total number of analgesics taken, and the duration of surgery were analyzed. A total of nine articles were included, six RCTs, two CCTs, and one retrospective study. Six studies had a low risk of bias and three had a moderate risk of bias. A statistically significant difference was found between piezoelectric surgery and conventional rotary instrument surgery for lower third molar extraction with regard to postoperative sequelae (oedema, trismus, and pain) and the total number of analgesics taken (P=0.0001, P=0.0001, P<0.00001, and P<0.0001, respectively). However, a statistically significant increased surgery time was required in the piezoelectric osteotomy group (P<0.00001). The results of the meta-analysis showed that piezoelectric surgery significantly reduced the occurrence of postoperative sequelae (oedema, trismus, and pain) and the total number of analgesics taken compared to the conventional rotary instrument technique in lower third molar surgery, but required a longer surgery time. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Fracture resistance of endodontically treated molars restored with horizontal fiberglass posts or indirect techniques.

PubMed

Bromberg, Carolina Ritter; Alves, Caroline Beatriz; Stona, Deborah; Spohr, Ana Maria; Rodrigues-Junior, Sinval Adalberto; Melara, Rafael; Burnett, Luiz Henrique

2016-12-01

Because of the many possibilities for endodontically restoring the posterior teeth and the high prevalence of restoration failures, this topic continues to be of major concern. A composite resin (CR) restoration reinforced by a horizontal fiberglass post may improve the fracture resistance of endodontically treated teeth. The authors investigated this possibility by comparing the fracture resistance of molars restored with direct techniques with that of molars restored with indirect techniques. The authors divided 50 extracted sound third molars into 5 groups: sound teeth, onlay (ON), inlay (IN), direct CR, and transfixed fiberglass post (TFP) plus direct CR. The authors performed standardized mesio-occlusodistal cavity preparations and endodontic treatments. The authors cemented indirect restorations of Lava Ultimate (3M ESPE) adhesively in the ON and IN groups. The authors restored CR group teeth directly with Filtek Z230 XT (3M ESPE). In the TFP group, the authors transfixed 2 fiberglass posts horizontally and restored the teeth directly with CR. Thereafter, the authors submitted the teeth to cyclic fatigue loading with 500,000 cycles at 200 newtons. The authors tested fracture resistance in newtons in a universal testing machine. The authors analyzed data with 1-way analysis of variance and a Tukey test (P < .05). Sound teeth had the highest fracture resistance. ON had the highest recovery of resistance, followed by TFP. CR had the lowest recovery, which was similar to that of IN. Endodontically treated molars restored with TFP plus CR had fracture resistance similar to those restored with ON, which was higher than that for IN or CR only. Horizontal TFPs placed inside a composite restoration had the same performance as did ON restorations. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

Carabelli's trait revisited: an examination of mesiolingual features at the enamel-dentine junction and enamel surface of Pan and Homo sapiens upper molars.

PubMed

Ortiz, Alejandra; Skinner, Matthew M; Bailey, Shara E; Hublin, Jean-Jacques

2012-10-01

Carabelli's trait is a morphological feature that frequently occurs on the mesiolingual aspect of Homo sapiens upper molars. Similar structures also referred to as Carabelli's trait have been reported in apes and fossil hominins. However, the morphological development and homology of these mesiolingual structures among hominoids are poorly understood. In this study, we employ micro-computed tomography to image the enamel-dentine junction (EDJ) and outer enamel surface (OES) of Pan (n = 48) and H. sapiens (n = 52) upper molars. We investigate the developmental origin of mesiolingual features in these taxa and establish the relative contribution of the EDJ and enamel cap to feature expression. Results demonstrate that mesiolingual features of H. sapiens molars develop at the EDJ and are similarly expressed at the OES. Morphological variation at both surfaces in this taxon can satisfactorily be assessed using standards for Carabelli's trait developed by the Arizona State University Dental Anthropology System (ASUDAS). Relative to H. sapiens, Pan has an even greater degree of correspondence in feature expression between the EDJ and OES. Morphological manifestations in Pan molars are not necessarily limited to the protocone and are best characterized by a lingual cingulum that cannot be captured by the ASUDAS. Cusp-like structures, similar to those seen in marked Carabelli's trait expressions in H. sapiens, were not found in Pan. This study provides a foundation for further analyses on the evolutionary history of mesiolingual dental traits within the hominoid lineage. It also highlights the wealth of morphological data that can be obtained at the EDJ for understanding tooth development and for characterizing tooth crown variation in worn fossil teeth. Copyright © 2012 Elsevier Ltd. All rights reserved.

Interdisciplinary treatment for a compensated Class II partially edentulous malocclusion: Orthodontic creation of a posterior implant site.

PubMed

Chiu, Grace; Chang, Chris; Roberts, W Eugene

2018-03-01

A 36-year-old woman with good periodontal health sought treatment for a compensated Class II partially edentulous malocclusion associated with a steep mandibular plane (SN-MP, 45°), 9 missing teeth, a 3-mm midline discrepancy, and compromised posterior occlusal function. She had multiple carious lesions, a failing fixed prostheses in the mandibular right quadrant replacing the right first molar, and a severely atrophic edentulous ridge in the area around the mandibular left first and second molars. After restoration of the caries, the mandibular left third molar served as anchorage to correct the mandibular arch crowding. The mandibular left second premolar was retracted with a light force of 2 oz (about 28.3 cN) on the buccal and lingual surfaces to create an implant site between the premolars. Modest lateral root resorption was noted on the distal surface of the mandibular left second premolar after about 7 mm of distal translation in 7 months. Six months later, implants were placed in the mandibular left and right quadrants; the spaces were retained with the fixed appliance for 5 months and a removable retainer for 1 month. Poor cooperation resulted in relapse of the mandibular left second premolar back into the implant site, and it was necessary to reopen the space. When the mandibular left fixture was uncovered, a 3-mm deep osseous defect on the distobuccal surface was found; it was an area of relatively immature bundle bone, because the distal aspect of the space was reopened after the relapse. Subsequent bone grafting resulted in good osseous support of the implant-supported prosthesis. The relatively thin band of attached gingiva on the implant at the mandibular right first molar healed with a recessed contour that was susceptible to food impaction. A free gingival graft restored soft tissue form and function. This severe malocclusion with a discrepancy index value of 28 was treated to an excellent outcome in 38 months of interdisciplinary treatment. The Cast-Radiograph Evaluation score was 13. However, the treatment was complicated by routine relapse and implant osseous support problems. Retreatment of space opening and 2 additional surgeries were required to correct an osseous defect and an inadequate soft tissue contour. Orthodontic treatment is a viable option for creating implant sites, but fixed retention is required until the prosthesis is delivered. Bone augmentation is indicated at the time of implant placement to offset expected bone loss. Complex restorative treatment may result in routine complications that are effectively managed with interdisciplinary care. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Characterization of branched ultrahigh molar mass polymers by asymmetrical flow field-flow fractionation and size exclusion chromatography.

PubMed

Otte, T; Pasch, H; Macko, T; Brüll, R; Stadler, F J; Kaschta, J; Becker, F; Buback, M

2011-07-08

The molar mass distribution (MMD) of synthetic polymers is frequently analyzed by size exclusion chromatography (SEC) coupled to multi angle light scattering (MALS) detection. For ultrahigh molar mass (UHM) or branched polymers this method is not sufficient, because shear degradation and abnormal elution effects falsify the calculated molar mass distribution and information on branching. High temperatures above 130 °C have to be applied for dissolution and separation of semi-crystalline materials like polyolefins which requires special hardware setups. Asymmetrical flow field-flow fractionation (AF4) offers the possibility to overcome some of the main problems of SEC due to the absence of an obstructing porous stationary phase. The SEC-separation mainly depends on the pore size distribution of the used column set. The analyte molecules can enter the pores of the stationary phase in dependence on their hydrodynamic volume. The archived separation is a result of the retention time of the analyte species inside SEC-column which depends on the accessibility of the pores, the residence time inside the pores and the diffusion ability of the analyte molecules. The elution order in SEC is typically from low to high hydrodynamic volume. On the contrary AF4 separates according to the diffusion coefficient of the analyte molecules as long as the chosen conditions support the normal FFF-separation mechanism. The separation takes place in an empty channel and is caused by a cross-flow field perpendicular to the solvent flow. The analyte molecules will arrange in different channel heights depending on the diffusion coefficients. The parabolic-shaped flow profile inside the channel leads to different elution velocities. The species with low hydrodynamic volume will elute first while the species with high hydrodynamic volume elute later. The AF4 can be performed at ambient or high temperature (AT-/HT-AF4). We have analyzed one low molar mass polyethylene sample and a number of narrow distributed polystyrene standards as reference materials with known structure by AT/HT-SEC and AT/HT-AF4. Low density polyethylenes as well as polypropylene and polybutadiene, containing high degrees of branching and high molar masses, have been analyzed with both methods. As in SEC the relationship between the radius of gyration (R(g)) or the molar mass and the elution volume is curved up towards high elution volumes, a correct calculation of the MMD and the molar mass average or branching ratio is not possible using the data from the SEC measurements. In contrast to SEC, AF4 allows the precise determination of the MMD, the molar mass averages as well as the degree of branching because the molar mass vs. elution volume curve and the conformation plot is not falsified in this technique. In addition, higher molar masses can be detected using HT-AF4 due to the absence of significant shear degradation in the channel. As a result the average molar masses obtained from AF4 are higher compared to SEC. The analysis time in AF4 is comparable to that of SEC but the adjustable cross-flow program allows the user to influence the separation efficiency which is not possible in SEC without a costly change of the whole column combination. Copyright © 2011 Elsevier B.V. All rights reserved.

Saving the 2(nd) Molar from the 3(rd) Is it Really the Guilt of the Tilt?

PubMed

Yadav, Pankaj; Pruthi, Preeti Jain; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

2016-05-01

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

A general approach to quantification of hydroxycinnamic acid derivatives and flavones, flavonols, and their glycosides by UV spectrophotometry

USDA-ARS?s Scientific Manuscript database

A general method was developed for the quantification of hydroxycinnamic acid derivatives and flavones, flavonols, and their glycosides based on the UV molar relative response factors (MRRF) of the standards. Each of these phenolic compounds contains a cinnamoyl structure and has a maximum absorban...

Factors that affect molecular weight distribution of Suwannee river fulvic acid as determined by electrospray ionization/mass spectrometry

USGS Publications Warehouse

Rostad, C.E.; Leenheer, J.A.

2004-01-01

Effects of methylation, molar response, multiple charging, solvents, and positive and negative ionization on molecular weight distributions of aquatic fulvic acid were investigated by electrospray ionization/mass spectrometry. After preliminary analysis by positive and negative modes, samples and mixtures of standards were derivatized by methylation to minimize ionization sites and reanalyzed.Positive ionization was less effective and produced more complex spectra than negative ionization. Ionization in methanol/water produced greater response than in acetonitrile/water. Molar response varied widely for the selected free acid standards when analyzed individually and in a mixture, but after methylation this range decreased. After methylation, the number average molecular weight of the Suwannee River fulvic acid remained the same while the weight average molecular weight decreased. These differences are probably indicative of disaggregation of large aggregated ions during methylation. Since the weight average molecular weight decreased, it is likely that aggregate formation in the fulvic acid was present prior to derivatization, rather than multiple charging in the mass spectra. ?? 2004 Elsevier B.V. All rights reserved.

Morphologic study of the maxillary molars. Part II: Internal anatomy.

PubMed

Pécora, J D; Woelfel, J B; Sousa Neto, M D; Issa, E P

1992-01-01

The internal anatomy of three hundred and seventy (370) decalcified and cleared human maxillary molars was studied. Seventy-five percent of the first molars, 58% of the second molars and 68% of the third molars studied presented three (3) root canals and 25% of the first molars, 42% of the second molars and 32% of the third molars presented four (4) root canals. The authors observed that the incidence of two root canals in the mesiobuccal root was higher in second maxillary molars than in first maxillary molars.

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

PubMed Central

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

2016-01-01

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

Age estimation standards for a Western Australian population using the coronal pulp cavity index.

PubMed

Karkhanis, Shalmira; Mack, Peter; Franklin, Daniel

2013-09-10

Age estimation is a vital aspect in creating a biological profile and aids investigators by narrowing down potentially matching identities from the available pool. In addition to routine casework, in the present global political scenario, age estimation in living individuals is required in cases of refugees, asylum seekers, human trafficking and to ascertain age of criminal responsibility. Thus robust methods that are simple, non-invasive and ethically viable are required. The aim of the present study is, therefore, to test the reliability and applicability of the coronal pulp cavity index method, for the purpose of developing age estimation standards for an adult Western Australian population. A total of 450 orthopantomograms (220 females and 230 males) of Australian individuals were analyzed. Crown and coronal pulp chamber heights were measured in the mandibular left and right premolars, and the first and second molars. These measurements were then used to calculate the tooth coronal index. Data was analyzed using paired sample t-tests to assess bilateral asymmetry followed by simple linear and multiple regressions to develop age estimation models. The most accurate age estimation based on simple linear regression model was with mandibular right first molar (SEE ±8.271 years). Multiple regression models improved age prediction accuracy considerably and the most accurate model was with bilateral first and second molars (SEE ±6.692 years). This study represents the first investigation of this method in a Western Australian population and our results indicate that the method is suitable for forensic application. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephen W. Feldberg; Lewis, Ernie R.

In this study, the principle of unchanging total concentration as described by Oldham and Feldberg [J. Phys. Chem. B, 103, 1699 (1999)] is invoked to analyze systems comprising a redox pair (X z1 1 and X z2 2) plus one or more non-electroactive species (X z3 3,X z4 4...X zjmax jmax) where X zj j is the j th species with charge z j and concentration; c j. The principle states that if the diffusion coefficients for all species are identical and mass transport is governed by the Nernst-Planck expression, the total concentration does not change during any electrochemical perturbation,more » i.e.: Σ jmax j=1[X zj j]=Σ jmax j=1 c j = S P With this principle we deduce the electrochemically induced difference between the surface and bulk concentrations for each species. Those concentration differences are translated into density differences which are a function of the density of the solvent and of the concentration differences, molecular masses and the standard partial molar volumes of all species. Those density differences in turn can induce convection that will ultimately modify the observed current. However, we did not attempt to quantify details of the natural convection and current modification produced by those density differences.« less

Comparative Study of Piezoelectric and Rotary Osteotomy Technique for Third Molar Impaction.

PubMed

Basheer, Sulphi A; Govind, R Jay; Daniel, Augustine; Sam, George; Adarsh, V J; Rao, Akshatha

2017-01-01

Bone removal is necessary for extracting the third molars that are erupted, partially erupted, and/or impacted in bone. Hence, it is necessary to choose a surgical method or instruments that conform to anatomic landmarks and are based on physiological principles. Many authors have reported injuries to the adjacent tooth, especially the distal part of periodontium after removal of second molar. Hence, the present study was undertaken to assess and compare the surgical and postsurgi-cal outcomes of third molar removal using piezoelectric surgery and rotary bur. A total of 30 healthy adult individuals who were in need of prophylactic removal of impacted man-dibular third molar tooth with ideal condition were included for the study. Individuals were divided randomly into study groups of 15 each, so that the difficulty of surgery will be the same in both the groups. Group I - piezoelectric osteotomy technique and group II - rotary osteotomy technique. The rotary device consists of a hand piece and a rotary speed ranging around 35,000 rpm was used. The piezoelectric device consists of a hand piece, and a frequency of 25 to 29 kHz with a microvibration of 60 to 200 mm/sec was used with a boosted working mode. Data were analyzed using unpaired t-test and qualitative data were analyzed using Fischer's exact test. The average age of the study subjects in the piezo-surgery group and rotary group was 28.40 ± 2.69 and 30.06 ± 3.15 years respectively. The time taken for removal of impacted tooth by rotary bur was less than that by piezoelectric device, which was significant statistically (p < 0.05). Until the 4th postoperative day, severity of pain experienced was more in the rotary group, which was statistically significant (p < 0.005). Mouth opening was significantly better in the piezoelectric group as compared with rotary bur until the 7th postoperative day. The piezosurgery method reduces postoperative pain, trismus, and swelling. Also, it may play an important role in increasing bone density within the extraction socket and decreasing the amount of bone loss of adjacent tooth in the distal aspect. In clinical practice, piezosurgery plays an important role because piezosurgery reduces postoperative pain, trismus, and also swelling.

Perioperative bromelain reduces pain and swelling and improves quality of life measures after mandibular third molar surgery: a randomized, double-blind, placebo-controlled clinical trial.

PubMed

Majid, Omer Waleed; Al-Mashhadani, Bashar Adil

2014-06-01

The purpose of the present study was to compare the effect of oral bromelain (4 × 250 mg) versus oral diclofenac sodium (4 × 25 mg) on pain, swelling, trismus, and quality of life (QOL) after surgical removal of impacted lower third molars. A randomized, double-blind, placebo-controlled study was planned. The sample included patients requiring extraction under local anesthesia of a single partial bony impacted mandibular third molar. The patients were randomly distributed into 1 of 3 groups: bromelain, diclofenac, and placebo. Treatment started 1 day before surgery and continued for 4 days. The predictor variable was the type of the drug given to the patients. The outcome variables were pain, swelling, and trismus, which were measured at 1, 3, and 7 days postoperatively. The other study variables included QOL measures to assess the patients' perception regarding the effect of surgery on their well-being and daily activities. A validated questionnaire was used to measure QOL. The data were analyzed using analysis of variance, multiple measures analysis of variance, or Pearson's χ(2) test, as appropriate. P < .05 was considered significant. A total of 45 subjects requiring surgical removal of a single impacted mandibular third molar under local anesthesia were included in the present study. The bromelain and diclofenac groups both showed a significant reduction in pain compared with the placebo group at all intervals (P < .05). Diclofenac also resulted in a significant reduction of swelling at 3 and 7 days, and bromelain resulted in an insignificant reduction. A nonsignificant reduction in trismus occurred in both treatment groups compared with the placebo group. Both treatment groups also showed a significant difference in the effect on QOL in most subscales and total scores (P < .05). The effect was comparable between the 2 treatment groups for all parameters and at all intervals. The results of our study have shown that oral bromelain is an effective therapy to improve the QOL after surgical removal of impacted lower third molars, with an effect on the postoperative sequelae comparable to that of preemptive diclofenac sodium. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Standardization of Epitopes for Human Chorionic Gonadotropin (hCG) Immunoassays.

PubMed

Berger, Peter; Lapthorn, Adrian J

2016-01-01

hCG and its variants are markers for pregnancy tests, pregnancyrelated complications, trophoblastic diseases, pre-natal screening of Down's syndrome and doping controls. Strong demands are imposed on diagnostic methods by the dynamic changes in the absolute and relative levels of hCG protein backbone variants and glycosylation isoforms in serum and urine during development of pregnancy or the progression/remission of tumors. Observed differences in the results between commercial diagnostic immunoassays reflect the unequal molar recognition of the different metabolic hCG variants, in particular the hCG beta core fragment (hCGβcf), by the diagnostic antibodies (Abs), as their epitopes are not standardized, and the fact that suboptimal hCG standards are used. To rapidly characterize Abs by their epitope recognition and specificity to evaluate their suitability for diagnostic immunoassays a procedure of comparative epitope mapping has been developed using epitope-defined reference Abs. Comparative epitope mapping of diagnostic Abs will provide the basis for the standardization of diagnostic antigenic domains/epitopes and consequently for improved reliability of hCG measurements. Diagnostic first line assays likely consist of pairs of Abs that recognize specific epitopes at the top of the neighboring peptide loops 1 and 3 (Ł1+3) and the cystine knot (ck) of hCGβ, respectively. In future, significant improvements of reliability, robustness and comparability of the results of immunoassays for complex glycoproteins such as hCG will be achieved by the use (i) of standardized diagnostic Abs against welldefined epitopes and (ii) of the new International Standards for hCG and for five hCG variants established by WHO, that are calibrated in molar (SI) units.

Does prophylactic administration of systemic antibiotics prevent postoperative inflammatory complications after third molar surgery?

PubMed

Halpern, Leslie R; Dodson, Thomas B

2007-02-01

To estimate and compare the frequencies of inflammatory complications after third molar (M3) surgery in subjects receiving intravenous prophylactic antibiotics or saline placebo. Using a placebo-controlled, double-blind, randomized clinical trial, the investigators enrolled a sample composed of subjects who required extraction of at least 1 impacted M3 and requested intravenous sedation or general anesthesia. The predictor variable was treatment group classified as active treatment (penicillin or clindamycin for penicillin-allergic subjects) or placebo (0.9% saline). Study medications were randomly assigned. Both surgeon and subject were blinded to treatment assignment. The medication was administered intravenously prior to any incision. The outcome variable was postoperative inflammatory complication classified as present or absent and included alveolar osteitis (AO) or surgical site infection (SSI). Other variables were demographic, anatomic, or operative. Descriptive and bivariate statistics were computed. Statistical significance was set at P < or = .05, single-tailed test of hypothesis. The sample was composed of 118 subjects (n = 59 per study group). In the active treatment group, there were no postoperative inflammatory complications. In the placebo group, 5 subjects (8.5%) were diagnosed with SSI, (P = .03). No subject met the case definition for AO. All SSIs were associated with the removal of partial bony or full bony impacted mandibular M3s. In the setting of third molar removal, these results suggest that the use of intravenous antibiotics administered prophylactically decrease the frequency of SSIs. The authors cannot comment on the efficacy of intravenous antibiotics in comparison to other antibacterial treatment regimens, eg chlorhexidine mouthrinse or intrasocket antibiotics.

Replacement of a first molar and 3 second molars by the mesial inclination of 4 impacted third molars in an adult with a Class II Division 1 malocclusion.

PubMed

Tomonari, Hiroshi; Yagi, Takakazu; Kuninori, Takaharu; Ikemori, Takahiro; Miyawaki, Shouichi

2015-06-01

This case report presents the successful replacement of 1 first molar and 3 second molars by the mesial inclination of 4 impacted third molars. A woman, 23 years 6 months old, had a chief complaint of crowding of her anterior teeth and linguoclination of a second molar on the left side. The panoramic radiographic images showed that the maxillary and mandibular third molars on both sides were impacted. Root resorption on the distal surfaces of the maxillary second molars was suspected. The patient was given a diagnosis of Angle Class II Division 1 malocclusion with severe crowding of the anterior teeth and 4 impacted third molars. After we extracted the treated maxillary second premolars and the second molars on both sides, the treated mandibular second premolar and the second molar on the left side, and the root canal-filled mandibular first molar on the right side, the 4 impacted third molars were uprighted and formed part of the posterior functional occlusion. The total active treatment period was 39 months. The maxillary and mandibular third molars on both sides successfully replaced the first and second molars. The replacement of a damaged molar by an impacted third molar is a useful treatment option for using sound teeth. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Study on small molecular organic compounds pyrolysed from rubber seed oil and its sodium soap.

PubMed

Fernando, T L D; Prashantha, M A B; Amarasinghe, A D U S

2016-01-01

Rubber seed oil (RSO) and its sodium soap were pyrolysed in a batch reactor to obtain low molar mass organic substances. The pyrolitic oil of RSO was redistilled and the distillates were characterized by GC-MS and FTIR. Density, acid value, saponification value and ester values were also measured according to the ASTM standard methods. A similar analysis was done for samples taken out at different time intervals from the reaction mixture. Industrially important low molar mass alkanes, alkenes, aromatics, cyclic compounds and carboxylic acids were identified in the pyrolysis process of rubber seed oil. However, pyrolysis of the sodium soap of rubber seed oil gave a mixture of hydrocarbons in the range of C14-C17 and hence it has more applications as a fuel.

An analytical model to design circumferential clasps for laser-sintered removable partial dentures.

PubMed

Alsheghri, Ammar A; Alageel, Omar; Caron, Eric; Ciobanu, Ovidiu; Tamimi, Faleh; Song, Jun

2018-06-21

Clasps of removable partial dentures (RPDs) often suffer from plastic deformation and failure by fatigue; a common complication of RPDs. A new technology for processing metal frameworks for dental prostheses based on laser-sintering, which allows for precise fabrication of clasp geometry, has been recently developed. This study sought to propose a novel method for designing circumferential clasps for laser-sintered RPDs to avoid plastic deformation or fatigue failure. An analytical model for designing clasps with semicircular cross-sections was derived based on mechanics. The Euler-Bernoulli elastic curved beam theory and Castigliano's energy method were used to relate the stress and undercut with the clasp length, cross-sectional radius, alloy properties, tooth type, and retention force. Finite element analysis (FEA) was conducted on a case study and the resultant tensile stress and undercut were compared with the analytical model predictions. Pull-out experiments were conducted on laser-sintered cobalt-chromium (Co-Cr) dental prostheses to validate the analytical model results. The proposed circumferential clasp design model yields results in good agreement with FEA and experiments. The results indicate that Co-Cr circumferential clasps in molars that are 13mm long engaging undercuts of 0.25mm should have a cross-section radius of 1.2mm to provide a retention of 10N and to avoid plastic deformation or fatigue failure. However, shorter circumferential clasps such as those in premolars present high stresses and cannot avoid plastic deformation or fatigue failure. Laser-sintered Co-Cr circumferential clasps in molars are safe, whereas they are susceptible to failure in premolars. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

The effects of lesion baseline characteristics and different Sr:Ca ratios in plaque fluid-like solutions on caries lesion de- and remineralization.

PubMed

Lippert, Frank

2012-10-01

This study investigated the effects of lesion baseline characteristics and different strontium (Sr) to calcium (Ca) ratios in plaque fluid-like solutions (PF) on lesion de- and remineralization. Caries lesions were formed in enamel using three protocols: methylcellulose acid gel (MeC) and partially saturated lactic acid solutions containing carboxymethylcellulose (CMC) or not (SOLN). Lesions were exposed to PF with four distinct Sr:Ca molar ratios (0:1/3:1:3), but otherwise identical composition and total Sr+Ca molarity, for seven days. Lesions were characterized using transverse microradiography (TMR) at baseline and post-treatment. At baseline, MeC and CMC had similar integrated mineral loss values, whereas SOLN lesions were more demineralized. All lesions showed significant differences in their mineral distributions, with CMC and SOLN having lower R values (integrated mineral loss to lesion depth ratio) than MeC. Post-PF exposure, no interaction was found between lesion type and Sr:Ca ratio. Within lesion type, MeC demineralized, whereas CMC and SOLN exhibited some remineralization, with the differences between MeC and the other lesion types being of statistical significance. Within Sr:Ca ratio, the 1:3 ratio exhibited some remineralization whereas other groups tended to demineralize. Only the difference between groups SrCa1/3 and SrCa0 was of statistical significance. In summary, both lesion baseline characteristics and Sr:Ca ratio were shown to effect lesion de- and remineralization. Under the conditions of the study, high-R lesions are more prone to demineralize under PF-like conditions than low-R lesions. In addition, partial Sr substitution for Ca in PF was shown to enhance lesion remineralization. Copyright © 2012 Elsevier Ltd. All rights reserved.

A three-dimensional finite element analysis of molar distalization with a palatal plate, pendulum, and headgear according to molar eruption stage.

PubMed

Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Kook, Yoon-Ah; Mo, Sung-Seo

2016-09-01

This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization.

Association of infantile bruxism and the terminal relationships of the primary second molars.

PubMed

Junqueira, Tatiana Helena; Nahás-Scocate, Ana Carla Raphaelli; Valle-Corotti, Karyna Martins do; Conti, Ana Claudia de Castro Ferreira; Trevisan, Shirley

2013-01-01

The aim of this study was to analyze the association between infantile bruxism and the terminal relationships of the primary second molars. A total of 937 pre-school children (both genders), aged from 2 to 6 years, from municipal schools in São Paulo were evaluated. In this study, a questionnaire considering the bruxism habit and the presence of headaches and/or restless sleep was answered by the parents/guardians. A clinical exam of occlusion in the anteroposterior direction (vertical plane - VP, mesial step - MS and distal step - DS) was performed by the examiners in the school environment. Student's t test, Fisher's test and a logistic regression test were applied for the statistical analysis at a significance level of 5%. The prevalence of the bruxism habit was 29.3% among the total sample. Because there was no significant difference between the sides evaluated, the left side was taken as the standard. Among those children with bruxism, 25.7% presented a mesial step terminal relationship at the primary second molars, 29.1% had DS, and 30.2% had VP. Regarding the association of the parafunctional habit with the type of terminal relationship, no significant results were found. Children who slept restlessly or suffered from headaches were verified to show a higher chance of expressing the habit (OR = 2.4 and 1.6, respectively). The prevalence of bruxism in the studied sample was 29.3%, and its association with the primary second molars' terminal relationship was not statistically significant.

Laser vs bur for bone cutting in impacted mandibular third molar surgery: A randomized controlled trial

PubMed Central

Passi, Deepak; Pal, Uma Shankar; Mohammad, Shadab; Singh, Rakesh Kumar; Mehrotra, Divya; Singh, Geeta; Kumar, Manoj; Chellappa, Arul A.L.; Gupta, Chandan

2013-01-01

Background The aim of this study was to assess the feasibility of Er: YAG laser in bone cutting for removal of impacted lower third molar teeth and compare its outcomes with that of surgical bur. Materials & methods The study comprised 40 subjects requiring removal of impacted mandibular third molar, randomly categorized into two equal groups of 20 each, who had their impacted third molar removed either using Er: YAG laser or surgical bur as per their group, using standard methodology of extraction of impacted teeth. Clinical parameters like pain, bleeding, time taken for bone cutting, postoperative swelling, trismus, wound healing and complications were compared for both groups. Observation & result Clinical parameters like pain, bleeding and swelling were lower in laser group than bur group, although the difference was statistically not significant. However, postoperative swelling showed significant difference in the two groups. Laser group required almost double the time taken for bone cutting with bur. Trismus persisted for a longer period in laser group. Wound healing and complications were assessed clinically and there was no significant difference in both the groups. Conclusion Based on the results of our study, the possibility of bone cutting using lasers is pursued, the osteotomy is easily performed and the technique is better suited to minimally invasive surgical procedures. The use of Er: YAG laser may be considered as an alternative tool to surgical bur, specially in anxious patients. PMID:25737885

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

PubMed

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

2013-06-05

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

Variation in form of mandibular, light, round, preformed NiTi archwires.

PubMed

Saze, Naomi; Arai, Kazuhito

2016-09-01

To evaluate the variation in form of nickel-titanium (NiTi) archwires by comparing them with the dental arch form of normal Japanese subjects before and after placing them in the first molar tubes. The mandibular dental casts of 30 normal subjects were scanned, and the dental arch depths and widths from the canine to the first molar were measured. Standardized images of 34 types of 0.016-inch preformed NiTi archwires were also taken in a 37°C environment, and the widths were measured and then classified by cluster analysis. Images of these archwires placed in a custom jig with brackets attached at the mean locations of the normal mandibular central incisors and first molar were additionally taken. The widths of the pooled and classified archwires were then compared with the normal dental arch widths before and after placement in the jig and among the groups (P < .05). The archwires were classified into three groups: small, medium, and large. The archwire widths in the small and medium groups were narrower than those at all examined tooth widths, except in the case of the premolars of the medium group. After placement in the jig, the pooled archwire widths were found to be significantly narrower and wider at the canine and second premolar, respectively, than at the dental arch, but not in the individual comparisons between groups. The variation observed in the mandibular NiTi archwire forms significantly decreased following fitting into the normal positions of the first molars.

Occlusal status in Asian male adults: prevalence and ethnic variation.

PubMed

Soh, Jen; Sandham, Andrew; Chan, Yiong Huak

2005-09-01

The purpose of this study was to determine the occlusal status in young Asian male adults of three ethnic groups. Study models of a sample of male army recruits (N = 339, age 17-22 years) with no history of orthodontic treatment were assessed. The ethnic proportions of the sample were Chinese 76.1% (n = 258), Malay 17.7% (n = 60), and Indian 6.2% (n = 21). British Standard Institute (BSI) and Angle's classification were used to determine incisor and molar relationships, respectively. Chi-square test or Fisher's Exact test was performed to compare the occlusal traits between ethnic groups. The distribution of incisor relationships of the total sample consisted of Class I = 48.1%, Class II/1 = 26.3%, Class II/2 = 3.2%, and Class III = 22.4%. Right Angle's molar relationships were 49.9%, 24.5%, and 24.2% whereas left Angle's molar relationships were 53.1%, 25.1%, and 21.2% for Class I, II, and III, respectively. Comparison between ethnic groups found that Indian subjects were more likely to have Class II/1 malocclusions and clinically missing permanent teeth (P < .05). The study found that the overall prevalence of malocclusion (BSI) was Class I, Class II/1, Class III, and Class II/2 in descending order of proportions. Angle's Class I molar was most prevalent followed by Class II and Class III relations. A significant difference in occlusal status between the ethnic groups was found regarding incisor relationship and missing permanent teeth (P < .05).

Vertical bone measurements from cone beam computed tomography images using different software packages.

PubMed

Vasconcelos, Taruska Ventorini; Neves, Frederico Sampaio; Moraes, Lívia Almeida Bueno; Freitas, Deborah Queiroz

2015-01-01

This article aimed at comparing the accuracy of linear measurement tools of different commercial software packages. Eight fully edentulous dry mandibles were selected for this study. Incisor, canine, premolar, first molar and second molar regions were selected. Cone beam computed tomography (CBCT) images were obtained with i-CAT Next Generation. Linear bone measurements were performed by one observer on the cross-sectional images using three different software packages: XoranCat®, OnDemand3D® and KDIS3D®, all able to assess DICOM images. In addition, 25% of the sample was reevaluated for the purpose of reproducibility. The mandibles were sectioned to obtain the gold standard for each region. Intraclass coefficients (ICC) were calculated to examine the agreement between the two periods of evaluation; the one-way analysis of variance performed with the post-hoc Dunnett test was used to compare each of the software-derived measurements with the gold standard. The ICC values were excellent for all software packages. The least difference between the software-derived measurements and the gold standard was obtained with the OnDemand3D and KDIS3D (-0.11 and -0.14 mm, respectively), and the greatest, with the XoranCAT (+0.25 mm). However, there was no statistical significant difference between the measurements obtained with the different software packages and the gold standard (p> 0.05). In conclusion, linear bone measurements were not influenced by the software package used to reconstruct the image from CBCT DICOM data.

Retained asymptomatic third molars and risk for second molar pathology.

PubMed

Nunn, M E; Fish, M D; Garcia, R I; Kaye, E K; Figueroa, R; Gohel, A; Ito, M; Lee, H J; Williams, D E; Miyamoto, T

2013-12-01

Prophylactic extraction of unerupted asymptomatic third molars is the most common oral surgery procedure in the United States. However, limited evidence exists to justify its costs and associated morbidity. We analyzed data collected over 25 years from 416 adult men enrolled in the Veterans Affairs Dental Longitudinal Study to evaluate the association of retained asymptomatic third molars with risk of adjacent second molar pathology (caries and/or periodontitis), based on third molar status (i.e., absent, erupted, or unerupted). Unerupted molars were further categorized as either "soft tissue" or "bony" impacted. We found that the lowest prevalence and incidence of second molar pathology occurred when the adjacent third molar was absent. The presence of a third molar that was soft tissue impacted increased the risk of incident second molar pathology 4.88-fold (95% confidence interval: 2.62, 9.08). Having an erupted or "bony" impacted third molar increased the risk of incident second molar pathology by 1.74 (95% confidence interval: 1.34, 2.25) and 2.16 (95% confidence interval: 1.56, 2.99), respectively. The retention of third molars is associated with increased risk of second molar pathology in middle-aged and older adult men.

Retained Asymptomatic Third Molars and Risk for Second Molar Pathology

PubMed Central

Nunn, M.E.; Fish, M.D.; Garcia, R.I.; Kaye, E.K.; Figueroa, R.; Gohel, A.; Ito, M.; Lee, H.J.; Williams, D.E.; Miyamoto, T.

2013-01-01

Prophylactic extraction of unerupted asymptomatic third molars is the most common oral surgery procedure in the United States. However, limited evidence exists to justify its costs and associated morbidity. We analyzed data collected over 25 years from 416 adult men enrolled in the Veterans Affairs Dental Longitudinal Study to evaluate the association of retained asymptomatic third molars with risk of adjacent second molar pathology (caries and/or periodontitis), based on third molar status (i.e., absent, erupted, or unerupted). Unerupted molars were further categorized as either “soft tissue” or “bony” impacted. We found that the lowest prevalence and incidence of second molar pathology occurred when the adjacent third molar was absent. The presence of a third molar that was soft tissue impacted increased the risk of incident second molar pathology 4.88-fold (95% confidence interval: 2.62, 9.08). Having an erupted or “bony” impacted third molar increased the risk of incident second molar pathology by 1.74 (95% confidence interval: 1.34, 2.25) and 2.16 (95% confidence interval: 1.56, 2.99), respectively. The retention of third molars is associated with increased risk of second molar pathology in middle-aged and older adult men. PMID:24132082

Diurnal Dynamics of Gaseous and Dissolved Metabolites and Microbiota Composition in the Bovine Rumen

PubMed Central

van Lingen, Henk J.; Edwards, Joan E.; Vaidya, Jueeli D.; van Gastelen, Sanne; Saccenti, Edoardo; van den Bogert, Bartholomeus; Bannink, André; Smidt, Hauke; Plugge, Caroline M.; Dijkstra, Jan

2017-01-01

Diurnal patterns of ruminal fermentation metabolites and microbial communities are not commonly assessed when investigating variation in ruminal CH4 production. The aims of this study were to monitor diurnal patterns of: (i) gaseous and dissolved metabolite concentrations in the bovine rumen, (ii) H2 and CH4 emitted, and (iii) the rumen microbiota. Furthermore, the effect of dietary inclusion of linseed oil on these patterns was assessed. Four rumen cannulated multiparous cows were used in a cross-over design with two 17 days periods and two dietary treatments: a control diet and a linseed oil supplemented diet [40% maize silage, 30% grass silage, 30% concentrate on dry matter (DM) basis for both diets; fat contents of 33 vs. 56 g/kg of DM]. On day 11, rumen contents were sampled for 10 h after morning feeding to profile gaseous and dissolved metabolite concentrations and microbiota composition. H2 and CH4 emission (mass per unit of time) was measured in respiration chambers from day 13 to 17. A 100-fold increase in ruminal H2 partial pressure (contribution to the total pressure of rumen headspace gases) was observed at 0.5 h after feeding. This peak was followed by a decline to basal level. Qualitatively similar patterns after feeding were also observed for H2 and CH4 emission, ethanol and lactate concentrations, and propionate molar proportion, although the opposite pattern was seen for acetate molar proportion. Associated with these patterns, a temporal biphasic change in the microbial composition was observed as based on 16S ribosomal RNA with certain taxa specifically associated with each phase. Bacterial concentrations (log10 16S ribosomal RNA gene copies based) were affected by time, and were increased by linseed oil supplementation. Archaeal concentrations (log10 16S ribosomal RNA gene copies based) tended to be affected by time and were not affected by diet, despite linseed oil supplementation decreasing CH4 emission, tending to decrease the partial pressure of CH4, and tending to increase propionate molar proportion. Linseed oil supplementation affected microbiota composition, and was most associated with an uncultivated Bacteroidales taxon. In summary, our findings support the importance of diurnal dynamics for the understanding of VFA, H2, and CH4 production. PMID:28367142

An odor interaction model of binary odorant mixtures by a partial differential equation method.

PubMed

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

2014-07-09

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.

Characteristics of hydrogen produced by partial oxidation and auto-thermal reforming in a small methanol reformer

NASA Astrophysics Data System (ADS)

Horng, Rong-Fang; Chou, Huann-Ming; Lee, Chiou-Hwang; Tsai, Hsien-Te

This paper investigates experimentally, the transient characteristics of a small methanol reformer using partial oxidation (POX) and auto-thermal reforming (ATR) for fuel cell applications. The parameters varied were heating temperature, methanol supply rate, steady mode shifting temperature, O 2/C (O 2/CH 3OH) and S/C (H 2O/CH 3OH) molar ratios with the main aim of promoting a rapid response and a high flow rate of hydrogen. The experiments showed that a high steady mode shifting temperature resulted in a faster temperature rise at the catalyst outlet and vice versa and that a low steady mode shifting temperature resulted in a lower final hydrogen concentration. However, when the mode shifting temperature was too high, the hydrogen production response was not necessarily improved. It was subsequently shown that the optimum steady mode shifting temperature for this experimental set-up was approximately 75 °C. Further, the hydrogen concentration produced by the auto-thermal process was as high as 49.12% and the volume flow rate up to 23.0 L min -1 compared to 40.0% and 20.5 L min -1 produced by partial oxidation.

Impacted lower third molars and distal caries in the mandibular second molar. Is prophylactic removal of lower third molars justified?

PubMed

Marques, José; Montserrat-Bosch, Marta; Figueiredo, Rui; Vilchez-Pérez, Miguel-Angel; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2017-06-01

The objective of this study was to evaluate the association between the presence of mandibular third molars and the occurrence of carious lesions in the distal aspect of the mandibular second molar. A retrospective cohort study comprising 327 lower third molars extracted in the Oral Surgery and Implantology Master's Degree program of the School of Dentistry of the University of Barcelona (Barcelona, Spain) was carried out. A descriptive and bivariate analysis was made. The diagnosis of caries in the second molar and the position of the mandibular third molar were evaluated through panoramic radiographies. The sample included 203 patients, 94 males (46.3%) and 109 females (53.7%), with a mean age of 26,8 years and 327 lower third molars. The prevalence of second molar distal caries was 25.4% (95% CI= 20.6% to 30.2%). This pathology was significantly more frequent when the third molar was in a horizontal position (27.7%), when the contact point was at (45,8%) or below (47.0%) the cementoenamel junction (CEJ), and when the distal CEJ of the mandibular second molar and the mesial CEJ of the third molar was 7 to 12 mm apart. Horizontal lower third molars with contact points at or below the CEJ are more likely to produce distal caries in the mandibular second molars. Due to the high prevalence of this pathology (20.6% to 30.2%), a prophylactic removal of lower third molars with the above-mentioned features might be advisable. Key words: Second molar, caries, third molar, prophylactic removal.

A three-dimensional finite element analysis of molar distalization with a palatal plate, pendulum, and headgear according to molar eruption stage

PubMed Central

Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Mo, Sung-Seo

2016-01-01

Objective This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization. PMID:27668192

Efficiency of molar distalization associated with second and third molar eruption stage.

PubMed

Flores-Mir, Carlos; McGrath, Lisa; Heo, Giseon; Major, Paul W

2013-07-01

To evaluate the efficiency of molar distalization associated with the second and third molar eruption stage. A systematic computerized database search was conducted using several databases. Adaptations of the terms molar distalization and distalizing appliances were used. The reference lists of all the selected articles were also searched for any potential articles that might have been missed in the electronic search. The data provided in the selected publications were grouped and analyzed in terms of molar distalization with respect to various eruption stages of maxillary second and third molars. Out of the 13 initially identified articles only four fulfilled the final selection criteria. Three of the four studies showed no statistical significance in linear molar distalization based on the eruptive stage of the second and/or third molars, while one study found that the amount of distal movement of the first molars was significantly greater in the group with unerupted second molars. Only one study found that the amount of molar tipping that occurred as a result of distalization was related to the eruption stage of the maxillary molars. Similarly, three of the four studies found that molar distalization time was not significantly affected by eruption of the second or third molars. The effect of maxillary second and third molar eruption stage on molar distalization-both linear and angular distalization-appears to be minimal. This conclusion is only based on low-level of evidence clinical trials. The large variability in the outcomes should be considered clinically.

Radiographic evaluation of third-molar development in relation to the chronological age of Turkish children in the southwest Eastern Anatolia region.

PubMed

Karataş, Orhan H; Öztürk, Fırat; Dedeoğlu, Numan; Çolak, Cemil; Altun, Oğuzhan

2013-10-10

To study the chronological age of third-molar mineralisation of Turkish children from the southwest Eastern Anatolia region, the Demirjian staging method was used to determine the stage of the mineralisation of four third molars (18, 28, 38 and 48) and to compare third-molar development by sex and age with the results of previous studies. The study comprised 832 Turkish children from the southwest Eastern Anatolia region aged 6-16 years based on radiological evidence from digital orthopantomograms. The mean age of the 832 patients was 11.03±1.98 years, with 424 males (mean age, 10.97±1.97) and 408 females (mean age, 11.09±2.00). The orthopantomograms were scored by two observers. The Wilcoxon matched-pairs signed-rank test used to assess intra- and inter-observer assessment revealed strong agreement between both observers' measurements. Statistical analysis of the association between sex and age was performed with the Mann-Whitney U-test and the Wilcoxon test. Regression analysis was performed to obtain regression formulae for calculating the dental and the chronological age. The statistical analysis showed a strong correlation between age and third-molar development in males (R(2)=0.61) and females (R(2)=0.63). New equations (age=7.49+0.69, development stage (DS) 38+0.70, DS18) were derived for estimation of the chronological age. The results showed that there was no significant difference in mineralisation between 18 and 28 and 38 and 48 in males or females. For both sexes, the dental age was lower than the chronological age. Males reached the developmental stages earlier than females. In the whole population, the boys' and the girls' dental ages were 0.84 years and 0.16 years earlier, respectively, than their chronological ages. The use of third-molar teeth as a developmental marker is suitable, particularly when comparing the obtained standard deviation with other skeletal-age calculation techniques. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

[Enamel damage depending on the method of bracket removal].

PubMed

Fischer-Brandies, H; Kremers, L; Reicheneder, C; Kluge, G; Hüsler, K

1993-04-01

Two different methods of removing brackets, on the one side by torsion and on the other by bending, were compared for the purpose of analyzing the respective enamel lesions. Each test group consisted of 19 extracted human molars with metal brackets attached to the molars by means of the "concise etching technique". Bracket removal was standardized through the use of a Wolpert "Universalprüfmaschine TZZ 707" with modified torsion and bending mechanism. A scanning electron microscope was used to analyze the enamel surface. When using the torsion method, the mean extension of the enamel lesions was 48.3% of the adhesive free enamel surface. These lesions often reached into the deeper enamel layers and were mainly to be found on the broad side of the bonded area. On the other hand, when using the bending method, the enamel lesions were less frequent. They were mainly superficial and were confined almost exclusively to the pressure zones. The stress required to remove the brackets and the stress distribution were calculated on mechanical models and these results corresponded well with the enamel lesions observed on the molars. It can thus be concluded that the method of removing brackets is clinically relevant in relation to enamel lesions.

Anesthetic Efficacy of 4 % Articaine During Extraction of the Mandibular Posterior Teeth by Using Inferior Alveolar Nerve Block and Buccal Infiltration Techniques.

PubMed

El-Kholey, Khalid E

2017-03-01

The study was designed to evaluate the anesthetic efficacy of 4 % articaine with 1:100,000 epinephrine (A100) in infiltration and inferior alveolar nerve block (IANB) anesthetic techniques for the pain control during extraction of the mandibular posterior teeth. This prospective randomized single-blind clinical trial included 100 patients needing extraction of at least two mandibular molars. Patients received either infiltration in the buccal vestibule opposite to the first molar supplemented with lingual infiltration or standard IANB with A100. For assessment of depth of anesthesia obtained by the two anaethetic techniques, presence or absence of pain during the extraction were rated using the visual analog scale. Fifty patients received infiltration anesthesia and fifty patients were anesthetized by IANB. The success rate of pain-free extraction after buccal infiltration was 94 %, whereas by using IANB with the same anesthetic it was 92 %. No statistical differences were detected in the success rates between the two anesthetic techniques ( P  = 0.15). Buccal Infiltration can be considered a good option during extraction of the mandibular molar and premolar teeth of course, with supplemental lingual anesthesia.

Cone-beam Computed Tomographic Study of Root Anatomy and Canal Configuration of Molars in a Spanish Population.

PubMed

Pérez-Heredia, Mercedes; Ferrer-Luque, Carmen María; Bravo, Manuel; Castelo-Baz, Pablo; Ruíz-Piñón, Manuel; Baca, Pilar

2017-09-01

The aim of this study was to identify morphologic peculiarities of roots and analyze the root canal configuration in maxillary and mandibular first and second molars by means using cone-beam computed tomographic (CBCT) imaging in a Spanish population. A total of 284 maxillary molars and 242 mandibular molars from 112 patients were examined in vivo by CBCT imaging; only untreated molars with healthy and fully matured apices were included in this study. Details regarding the number of roots, number of canals, and root canal configuration were recorded. Maxillary first and second molars had 3 roots in 97.2% and 79%, respectively. In mandibular molars, the frequency of 2 roots was 94% in first molars and 83% in second molars. The canal configuration of the palatal root was 100% Vertucci type I (1-1) in first and second molars. The distobuccal root showed a Vertucci type I configuration in 97% of first and 100% of maxillary second molars. The mesiobuccal root for first molars showed a Vertucci type II configuration (2-1) in 56.5% cases and Vertucci type IV (2-2) in 23.2%. For maxillary second molars, the Vertucci type I configuration reached 52.7%. In mandibular molars, the mesial root showed higher variability. Most frequent was the presence of 2 canals, Vertucci type II for first and second molars. In the distal root, the most common configuration was Vertucci type I in both molars. The greater percentage of fused roots was observed in maxillary molars. Vertucci type II configuration was more frequent than type IV in the mesial root of mandibular molars and the mesiobuccal root of maxillary molars. A third canal in the mesial root of first mandibular molars (6.7%) was higher than expected. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

An interlaboratory study of TEX86 and BIT analysis of sediments, extracts, and standard mixtures

NASA Astrophysics Data System (ADS)

Schouten, Stefan; Hopmans, Ellen C.; Rosell-Melé, Antoni; Pearson, Ann; Adam, Pierre; Bauersachs, Thorsten; Bard, Edouard; Bernasconi, Stefano M.; Bianchi, Thomas S.; Brocks, Jochen J.; Carlson, Laura Truxal; Castañeda, Isla S.; Derenne, Sylvie; Selver, Ayça. Doǧrul; Dutta, Koushik; Eglinton, Timothy; Fosse, Celine; Galy, Valier; Grice, Kliti; Hinrichs, Kai-Uwe; Huang, Yongsong; Huguet, Arnaud; Huguet, Carme; Hurley, Sarah; Ingalls, Anitra; Jia, Guodong; Keely, Brendan; Knappy, Chris; Kondo, Miyuki; Krishnan, Srinath; Lincoln, Sara; Lipp, Julius; Mangelsdorf, Kai; Martínez-García, Alfredo; Ménot, Guillemette; Mets, Anchelique; Mollenhauer, Gesine; Ohkouchi, Naohiko; Ossebaar, Jort; Pagani, Mark; Pancost, Richard D.; Pearson, Emma J.; Peterse, Francien; Reichart, Gert-Jan; Schaeffer, Philippe; Schmitt, Gaby; Schwark, Lorenz; Shah, Sunita R.; Smith, Richard W.; Smittenberg, Rienk H.; Summons, Roger E.; Takano, Yoshinori; Talbot, Helen M.; Taylor, Kyle W. R.; Tarozo, Rafael; Uchida, Masao; van Dongen, Bart E.; Van Mooy, Benjamin A. S.; Wang, Jinxiang; Warren, Courtney; Weijers, Johan W. H.; Werne, Josef P.; Woltering, Martijn; Xie, Shucheng; Yamamoto, Masanobu; Yang, Huan; Zhang, Chuanlun L.; Zhang, Yige; Zhao, Meixun; Damsté, Jaap S. Sinninghe

2013-12-01

Two commonly used proxies based on the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) are the TEX86 (TetraEther indeX of 86 carbon atoms) paleothermometer for sea surface temperature reconstructions and the BIT (Branched Isoprenoid Tetraether) index for reconstructing soil organic matter input to the ocean. An initial round-robin study of two sediment extracts, in which 15 laboratories participated, showed relatively consistent TEX86 values (reproducibility ±3-4°C when translated to temperature) but a large spread in BIT measurements (reproducibility ±0.41 on a scale of 0-1). Here we report results of a second round-robin study with 35 laboratories in which three sediments, one sediment extract, and two mixtures of pure, isolated GDGTs were analyzed. The results for TEX86 and BIT index showed improvement compared to the previous round-robin study. The reproducibility, indicating interlaboratory variation, of TEX86 values ranged from 1.3 to 3.0°C when translated to temperature. These results are similar to those of other temperature proxies used in paleoceanography. Comparison of the results obtained from one of the three sediments showed that TEX86 and BIT indices are not significantly affected by interlaboratory differences in sediment extraction techniques. BIT values of the sediments and extracts were at the extremes of the index with values close to 0 or 1, and showed good reproducibility (ranging from 0.013 to 0.042). However, the measured BIT values for the two GDGT mixtures, with known molar ratios of crenarchaeol and branched GDGTs, had intermediate BIT values and showed poor reproducibility and a large overestimation of the "true" (i.e., molar-based) BIT index. The latter is likely due to, among other factors, the higher mass spectrometric response of branched GDGTs compared to crenarchaeol, which also varies among mass spectrometers. Correction for this different mass spectrometric response showed a considerable improvement in the reproducibility of BIT index measurements among laboratories, as well as a substantially improved estimation of molar-based BIT values. This suggests that standard mixtures should be used in order to obtain consistent, and molar-based, BIT values.

Impacted lower third molars and distal caries in the mandibular second molar. Is prophylactic removal of lower third molars justified?

PubMed Central

Marques, José; Montserrat-Bosch, Marta; Vilchez-Pérez, Miguel-Angel; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2017-01-01

Background The objective of this study was to evaluate the association between the presence of mandibular third molars and the occurrence of carious lesions in the distal aspect of the mandibular second molar. Material and Methods A retrospective cohort study comprising 327 lower third molars extracted in the Oral Surgery and Implantology Master’s Degree program of the School of Dentistry of the University of Barcelona (Barcelona, Spain) was carried out. A descriptive and bivariate analysis was made. The diagnosis of caries in the second molar and the position of the mandibular third molar were evaluated through panoramic radiographies. Results The sample included 203 patients, 94 males (46.3%) and 109 females (53.7%), with a mean age of 26,8 years and 327 lower third molars. The prevalence of second molar distal caries was 25.4% (95% CI= 20.6% to 30.2%). This pathology was significantly more frequent when the third molar was in a horizontal position (27.7%), when the contact point was at (45,8%) or below (47.0%) the cementoenamel junction (CEJ), and when the distal CEJ of the mandibular second molar and the mesial CEJ of the third molar was 7 to 12 mm apart. Conclusions Horizontal lower third molars with contact points at or below the CEJ are more likely to produce distal caries in the mandibular second molars. Due to the high prevalence of this pathology (20.6% to 30.2%), a prophylactic removal of lower third molars with the above-mentioned features might be advisable. Key words:Second molar, caries, third molar, prophylactic removal. PMID:28638558

Multivariate Quantification of the Solid State Phase Composition of Co-Amorphous Naproxen-Indomethacin.

PubMed

Beyer, Andreas; Grohganz, Holger; Löbmann, Korbinian; Rades, Thomas; Leopold, Claudia S

2015-10-27

To benefit from the optimized dissolution properties of active pharmaceutical ingredients in their amorphous forms, co-amorphisation as a viable tool to stabilize these amorphous phases is of both academic and industrial interest. Reports dealing with the physical stability and recrystallization behavior of co-amorphous systems are however limited to qualitative evaluations based on the corresponding X-ray powder diffractograms. Therefore, the objective of the study was to develop a quantification model based on X-ray powder diffractometry (XRPD), followed by a multivariate partial least squares regression approach that enables the simultaneous determination of up to four solid state fractions: crystalline naproxen, γ-indomethacin, α-indomethacin as well as co-amorphous naproxen-indomethacin. For this purpose, a calibration set that covers the whole range of possible combinations of the four components was prepared and analyzed by XRPD. In order to test the model performances, leave-one-out cross validation was performed and revealed root mean square errors of validation between 3.11% and 3.45% for the crystalline molar fractions and 5.57% for the co-amorphous molar fraction. In summary, even four solid state phases, involving one co-amorphous phase, can be quantified with this XRPD data-based approach.

Predictive model of third molar eruption after second molar extraction.

PubMed

De-la-Rosa-Gay, Cristina; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2010-03-01

Extraction of second permanent molars is an option for providing space in orthodontic treatment. Although many articles have described its impact on the outcome, there are few data on the prognosis of the eruption of the adjacent third molars. The aims of this investigation were to provide predictive models of eruption of third molars after second permanent molar extraction and to validate them. A total of 48 patients (ages, 11-23 years) who had 128 second permanent molars (54 maxillary, 74 mandibular) extracted during orthodontic treatment were followed until eruption of the third molars was complete. A lineal regression model predicted the final angle of the third molars with the permanent first molar by using the variables of initial angle, jaw, and the developmental stage of the third molar. A logistic regression model predicted the probability of correct eruption by using the variables of initial angle, jaw, sex, age, and the developmental stage of the third molar. 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Correction of a mutilated dentition with mini-implants as anchorage.

PubMed

Hyun, Jae-Man; Kim, Tae-Woo

2010-11-01

The patient was an adolescent boy, aged 15.6 years, with a mutilated dentition. He had extrusion of the maxillary left first molar because of loss of the mandibular first molar and lingual tilting and rotation of the mandibular second molars. Both left and right second molars were in scissors-bite that was more severe on the left side. By using mini-implants and a TPA with hooks, a 3-mm intrusion was successfully made on the maxillary left first molar. This provided room for mesial movement of the mandibular left second molar. The second molar was protracted into the space of the missing first molar, and the mandibular left third molar was positioned in place of the second molar. The second molars scissors-bite was corrected. Active treatment took 45 months, and the treatment result remained stable 2 years after debonding. Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Polarizability of Helium, Neon, and Argon: New Perspectives for Gas Metrology

NASA Astrophysics Data System (ADS)

Gaiser, Christof; Fellmuth, Bernd

2018-03-01

With dielectric-constant gas thermometry, the molar polarizability of helium, neon, and argon has been determined with relative standard uncertainties of about 2 parts per million. A series of isotherms measured with the three noble gases and two different experimental setups led to this unprecedented level of uncertainty. These data are crucial for scientists in the field of gas metrology, working on pressure and temperature standards. Furthermore, with the new benchmark values for neon and argon, theoretical calculations, today about 3 orders of magnitude larger in uncertainty, can be checked and improved.

Polarizability of Helium, Neon, and Argon: New Perspectives for Gas Metrology.

PubMed

Gaiser, Christof; Fellmuth, Bernd

2018-03-23

With dielectric-constant gas thermometry, the molar polarizability of helium, neon, and argon has been determined with relative standard uncertainties of about 2 parts per million. A series of isotherms measured with the three noble gases and two different experimental setups led to this unprecedented level of uncertainty. These data are crucial for scientists in the field of gas metrology, working on pressure and temperature standards. Furthermore, with the new benchmark values for neon and argon, theoretical calculations, today about 3 orders of magnitude larger in uncertainty, can be checked and improved.

Isolation and partial purification of cadmium-binding protein from roots of the grass Agrostis gigantea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rauser, W.E.

1984-04-01

A cadmium-binding protein was isolated from roots of the grass Agrostis gigantea Roth. Heat-stable proteins were chromatographed on the anion exchanger QAE-Sephadex A-25. The major cadmium fraction was purified further by gel filtration of Sephadex G-75 in 1 molar KCI buffer. The resulting protein preparation was light brown, had an apparent molecular weight of 3700, contained 29% cysteine and close to 4 gram atoms cadmium/mole. The cadmium:cysteine ratio was l:2.7. Spectroscopic measurments indicated cadmium-thiolate coordination. The roots produced the metallothionein-like protein when they were exposed to cadmium for 7 days.

Theory of anomalous critical-cluster content in high-pressure binary nucleation.

PubMed

Kalikmanov, V I; Labetski, D G

2007-02-23

Nucleation experiments in binary (a-b) mixtures, when component a is supersaturated and b (carrier gas) is undersaturated, reveal that for some mixtures at high pressures the a content of the critical cluster dramatically decreases with pressure contrary to expectations based on classical nucleation theory. We show that this phenomenon is a manifestation of the dominant role of the unlike interactions at high pressures resulting in the negative partial molar volume of component a in the vapor phase beyond the compensation pressure. The analysis is based on the pressure nucleation theorem for multicomponent systems which is invariant to a nucleation model.

Salt Potentiates Methylamine Counteraction System to Offset the Deleterious Effects of Urea on Protein Stability and Function

PubMed Central

Singh, Laishram R.; Warepam, Marina; Ahmad, Faizan; Dar, Tanveer Ali

2015-01-01

Cellular methylamines are osmolytes (low molecular weight organic compounds) believed to offset the urea’s harmful effects on the stability and function of proteins in mammalian kidney and marine invertebrates. Although urea and methylamines are found at 2:1 molar ratio in tissues, their opposing effects on protein structure and function have been questioned on several grounds including failure to counteraction or partial counteraction. Here we investigated the possible involvement of cellular salt, NaCl, in urea-methylamine counteraction on protein stability and function. We found that NaCl mediates methylamine counteracting system from no or partial counteraction to complete counteraction of urea’s effect on protein stability and function. These conclusions were drawn from the systematic thermodynamic stability and functional activity measurements of lysozyme and RNase-A. Our results revealed that salts might be involved in protein interaction with charged osmolytes and hence in the urea-methylamine counteraction. PMID:25793733

Prediction of Setschenow constants of N-heteroaromatics in NaCl solutions based on the partial charge on the heterocyclic nitrogen atom.

PubMed

Yang, Bin; Li, Zhongjian; Lei, Lecheng; Sun, Feifei; Zhu, Jingke

2016-02-01

The solubilities of 19 different kinds of N-heteroaromatic compounds in aqueous solutions with different concentrations of NaCl were determined at 298.15 K with a UV-vis spectrophotometry and titration method, respectively. Setschenow constants, Ks, were employed to describe the solubility behavior, and it is found that the higher ring numbers of N-heteroaromatics gave rise to the lower values of Ks. Moreover, Ks showed a good linear relationship with the partial charge on the nitrogen atom (QN) for either QN > 0 or QN < 0 N-heteroaromatics. It further revealed that QN was well-matched in the prediction of salting-out effect for N-heteroaromatics compared to the conventional descriptors such as molar volume (VH) and the octanol-water partition coefficient (Kow). The heterocyclic N in N-heteroaromatics may interact with Na(+) ions in NaCl solution for QN < 0 and with Cl(-) for QN > 0.

Oxygen nonstoichiometry and thermodynamic quantities in solid solution SrFe1-xSnxO3-δ

NASA Astrophysics Data System (ADS)

Merkulov, O. V.; Markov, A. A.; Leonidov, I. A.; Patrakeev, M. V.; Kozhevnikov, V. L.

2018-06-01

The oxygen content (3-δ) variations in tin substituted derivatives SrFe1-xSnxO3-δ, where x = 0.05, 0.1, 0.17 and 0.25, of perovskite-like strontium ferrite, have been studied by coulometric titration measurements within oxygen partial pressure (pO2) range 10-19-10-2 atm at 800-950 °С. The obtained dependencies of (3-δ) from pO2 and temperature are used for calculations of partial molar thermodynamic functions of oxygen in the oxide structure. It is found that a satisfactory explanation of the experimental results can be attained within frameworks of the ideal solution model with ion and electron defects appearing in the result of oxidation and disproportionation of iron cations. The increase of the oxidation reaction enthalpy with tin content is consistent with the increase of the unit cell parameter, i.e., the stretch and relaxation of Fe-O chemical bonds.

77 FR 64737 - Partial Approval and Partial Disapproval of Air Quality State Implementation Plans; Nevada...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-23

... standard was set at 15 micrograms per cubic meter ([mu]g/m\\3\\), based on the 3-year average of annual... 2.5 standard was set at 65 [mu]g/m\\3\\, based on the 3- year average of the 98th percentile of 24... partially approve the submittal based on EPA's independent evaluation of Nevada's impact on receptor states...

Antimicrobial Activity of Photodynamic Therapy Against Enterococcus faecalis Before and After Reciprocating Instrumentation in Permanent Molars.

PubMed

Pinheiro, Sérgio Luiz; Azenha, Giuliana Rodrigues; Democh, Yasmin Marialva; Nunes, Daniela Camila; Provasi, Silvia; Fontanetti, Giovana Masiero; Duarte, Danilo Antônio; Fontana, Carlos Eduardo; da Silveira Bueno, Carlos Eduardo

2016-12-01

The present study sought to evaluate the antimicrobial activity against Enterococcus faecalis of photodynamic therapy applied before and after reciprocating instrumentation of permanent molars. Apical extrusion of debris can cause flare-ups due to introduction of bacteria into the periapical tissues. Eighteen mesial roots from permanent mandibular molars were selected. The crowns were removed to obtain a standard root length of 15 mm. The included mesial roots had an angulation of 10°-40° and canals with independent foramina. The orifice of each mesiolingual canal was sealed with light-curing resin, and the working length was established visually, 1 mm short of the apical foramen. The roots were rendered impermeable and sterilized, and the mesiobuccal canals were contaminated with a standard strain of E. faecalis for 21 days. Specimens were randomly divided into three groups (n = 6): G1, photodynamic therapy performed before instrumentation and irrigation with 0.9% NaCl (saline) solution; G2, photodynamic therapy performed after instrumentation and irrigation with 0.9% NaCl; and G3 (control), instrumentation and irrigation with 2.5% NaOCl (sodium hypochlorite) solution. Canals were shaped with a WaveOne primary file (25.08) and irrigated with 0.9% NaCl. E. faecalis samples were collected before and after each procedure, and the results were analyzed using descriptive statistics and the Kruskal-Wallis and Wilcoxon tests. Significant reductions in E. faecalis were observed when photodynamic therapy was performed before and after instrumentation of the root canal system (p < 0.05). Reciprocating instrumentation significantly reduced E. faecalis colonies in experimentally contaminated root canal systems (p < 0.05). Photodynamic therapy was effective in removing E. faecalis from the root canal system, whether performed before or after reciprocating instrumentation.

AXIAL MODIFICATIONS OF PERMANENT LOWER MOLARS AFTER PREMATURE LOSSES OF TEMPORARY MOLARS.

PubMed

Cernei, E R; Mavru, R B; Zetu, Irina Nicoleta

2016-01-01

The aim of our study was to determine the impact of premature loss of temporary lower molars upon the longitudinal axis of the first and second permanent molars. The study groups included 61 patients, 6-9 year olds with premature loss of primary molars and a control group of 24 patients with intact temporary teeth. We evaluated the angle between longitudinal axis of first and second lower permanent molars and occlusal plane. It was observed that premature loss of lower second deciduous molar modifies more the vertical axis of first and second permanent molars than the premature loss of first lower primary molar. Reducing space occurs mainly through mesial inclination of molars that separates the edentulous breach. Temporary loss of both lower first molars on the same quadrant causes an accelerated eruption of both premolars increasing the prevalence of eruption sequence: "4-5-3-7". The preservation of the occlusal morpho-functional complex using space maintainers mainly when the premature loss of the second primary molars occurs is the best interceptive treatment option.

Hydro-isomerization of n-hexane on bi-functional catalyst: Effect of total and hydrogen partial pressures

NASA Astrophysics Data System (ADS)

Thoa, Dao Thi Kim; Loc, Luu Cam

2017-09-01

The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.

Early extraction of the mandibular third molar in case of eruption disturbances of the second molar.

PubMed

Kavadia, S; Antoniades, K; Kaklamanos, E; Antoniades, V; Markovitsi, E; Zafiriadis, L

2003-01-01

General consensus has been reached on extracting mandibular third molars when they are involved in pathologic processes. However, early extraction is advisable in cases of eruption disturbances of the mandibular second molar, before or during orthodontic treatment. Thirty-two patients with early extraction of the mandibular third molar before or during orthodontic treatment were examined. In these cases either the presence of the third molar presented an obstacle in the eruption path of the second, or third molar germ removal was considered beneficial to the course of orthodontic treatment. Early extraction of the mandibular third molar facilitates the eruption of the second molar, especially in cases where evidence of crowding and lack of space in the posterior mandibular region exist. Orthodontic treatment may, in some cases, aggravate eruption disturbances of the second molar.

Influence of third molar space on angulation and dental arch crowding.

PubMed

Hasegawa, Yuh; Terada, Kazuto; Kageyama, Ikuo; Tsuchimochi, Takashi; Ishikawa, Fujiro; Nakahara, Sen

2013-01-01

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding.

Use of cone beam computed tomography to assess significant imaging findings related to mandibular third molar impaction.

PubMed

Matzen, Louise Hauge; Schropp, Lars; Spin-Neto, Rubens; Wenzel, Ann

2017-11-01

The aim of the study was to identify risk factors for pathoses related to mandibular third molars observed in cone beam computed tomography. Cone beam computed tomography volumes of 410 mandibular third molars were assessed by 3 observers, according to the angulation and position of the third molar in relation to the second molar. In addition, pathoses (marginal bone loss, resorption of the second molar, increased follicular space and lingual bone perforation) were assessed. Logistic regression analyses were used to test whether the angulation and position of the third molar were risk factors for pathoses. On average, 41% of second molars had resorption; mesioangulated (odds ratio [OR] 11-107; P < .001) and horizontally positioned (OR 13-120; P < .001) third molars located cervically at the second molar (OR 2-3; P < .027) significantly increased the risk. On average, 49% of second molars had marginal bone loss; mesioangulated (OR 16-85; P < .001) and horizontally positioned (OR 61-573; P < .001) third molars increased the risk. For the third molar, an increased follicular space was seen in 25% of cases; distal (OR 5-9; P < .001) and vertical positions (OR 5; P < .002) increased the risk. Lingual bone perforation was not related to a specific angulation. Specific angulations of the mandibular third molar are risk factors for marginal bone loss and resorption of the second molar. Copyright © 2017 Elsevier Inc. All rights reserved.

A counter-intuitive approach to calculating non-exchangeable 2H isotopic composition of hair: treating the molar exchange fraction fE as a process-related rather than compound-specific variable

USGS Publications Warehouse

Landwehr, J.M.; Meier-Augenstein, W.; Kemp, H.F.

2011-01-01

Hair is a keratinous tissue that incorporates hydrogen from material that an animal consumes but it is metabolically inert following synthesis. The stable hydrogen isotope composition of hair has been used in ecological studies to track migrations of mammals as well as for forensic and archaeological purposes to determine the provenance of human remains or the recent geographic life trajectory of living people. Measurement of the total hydrogen isotopic composition of a hair sample yields a composite value comprised of both metabolically informative, non-exchangeable hydrogen and exchangeable hydrogen, with the latter reflecting ambient or sample preparation conditions. Neither of these attributes is directly measurable, and the non-exchangeable hydrogen composition is obtained by estimation using a commonly applied mathematical expression incorporating sample measurements obtained from two distinct equilibration procedures. This commonly used approach treats the fraction of exchangeable hydrogen as a mixing ratio, with a minimal procedural fractionation factor assumed to be close or equal to 1. Instead, we propose to use full molar ratios to derive an expression for the non-exchangeable hydrogen composition explicitly as a function of both the procedural fractionation factor α and the molar hydrogen exchange fraction fE. We apply these derivations in a longitudinal study of a hair sample and demonstrate that the molar hydrogen exchange fraction fE should, like the procedural fractionation factor α, be treated as a process-dependent parameter, i.e. a reaction-specific constant. This is a counter-intuitive notion given that maximum theoretical values for the molar hydrogen exchange fraction fE can be calculated that are arguably protein-type specific and, as such, fE could be regarded as a compound-specific constant. We also make some additional suggestions for future approaches to determine the non-exchangeable hydrogen composition of hair and the use of standards.

Immediate transmucosal implant placement in molar extraction sites: a 12-month prospective multicenter cohort study.

PubMed

Cafiero, C; Annibali, S; Gherlone, E; Grassi, F R; Gualini, F; Magliano, A; Romeo, E; Tonelli, P; Lang, N P; Salvi, G E

2008-05-01

To assess the clinical and radiographic outcomes of immediate transmucosal placement of implants into molar extraction sockets. Twelve-month multicenter prospective cohort study. Following molar extraction, tapered implants with an endosseous diameter of 4.8 mm and a shoulder diameter of 6.5 mm were immediately placed into the sockets. Molars with evidence of acute periapical pathology were excluded. After implant placement and achievement of primary stability, flaps were repositioned and sutured allowing a non-submerged, transmucosal healing. Peri-implant marginal defects were treated according to the principles of guided bone regeneration (GBR) by means of deproteinized bovine bone mineral particles in conjunction with a bioresrobable collagen membrane. Standardized radiographs were obtained at baseline and 12 months thereafter. Changes in depth and width of the distance from the implant shoulder (IS) and from the alveolar crest (AC) to the bottom of the defect (BD) were assessed. Eighty-two patients (42 males and 40 females) were enrolled and followed for 12 months. They contributed with 82 tapered implants. Extraction sites displayed sufficient residual bone volume to allow primary stability of all implants. Sixty-four percent of the implants were placed in the areas of 36 and 46. GBR was used in conjunction with the placement of all implants. No post-surgical complications were observed. All implants healed uneventfully yielding a survival rate of 100% and healthy soft tissue conditions after 12 months. Radiographically, statistically significant changes (P<0.0001) in mesial and distal crestal bone levels were observed from baseline to the 12-month follow-up. The findings of this 12-month prospective cohort study showed that immediate transmucosal implant placement represented a predictable treatment option for the replacement of mandibular and maxillary molars lost due to reasons other than periodontitis including vertical root fractures, endodontic failures and caries.

Specific and total N-nitrosamines formation potentials of nitrogenous micropollutants during chloramination.

PubMed

Piazzoli, Andrea; Breider, Florian; Aquillon, Caroline Gachet; Antonelli, Manuela; von Gunten, Urs

2018-05-15

N-nitrosamines are a group of potent human carcinogens that can be formed during oxidative treatment of drinking water and wastewater. Many tertiary and quaternary amines present in consumer products (e.g., pharmaceuticals, personal care and household products) are known to be N-nitrosodimethylamine (NDMA) precursors during chloramination, but the formation of other N-nitrosamines has been rarely studied. This study investigates the specific and total N-nitrosamine (TONO) formation potential (FP) of various precursors from nitrogen-containing micropollutants (chlorhexidine, metformin, benzalkonium chloride and cetyltrimethylammonium chloride) and tertiary and quaternary model amines (trimethyl amine, N,N-dimethylbutyl amine, N,N-dimethylbenzyl amine and tetramethyl ammonium). All the studied nitrogenous micropollutants displayed quantifiable TONO FP, with molar yields in the range 0.04-11.92%. However, the observed TONO pools constituted mostly of uncharacterized species, not included in US-EPA 8270 N-nitrosamines standard mix. Only the quaternary ammonium compound benzalkonium chloride showed quantifiable NDMA FP (0.56% molar yield), however, explaining only a minor fraction of the observed TONO FP. The studied model amines showed molar NDMA yields from 0.10% (trimethyl amine) to 5.05% (N,N-dimethylbenzyl amine), very similar to the molar TONO yields. The comparison of the FPs of micropollutants and model compounds showed that the presence of electron donating functional groups (such as a benzyl group) in tertiary and quaternary amine precursors leads to a higher formation of NDMA and uncharacterized N-nitrosamines, respectively. LC-qTOF screening of a list of proposed N-nitrosamine structures has enabled to identify a novel N-nitrosamine (N-nitroso-N-methyldodecylamine) from the chloramination of benzalkonium chloride. This finding supports the hypothesis that different functional groups in quaternary amines can act as leaving groups during chloramination and form differing N-nitrosamine structures at significant yield. Molar TONO yields determined for micropollutants were finally validated under experimental conditions closer to real water matrices, confirming their representativeness also for lower concentration ranges. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oral Health-Related Quality of Life Following Third Molar Surgery in an African Population

PubMed Central

Ibikunle, Adebayo Aremu; Adeyemo, Wasiu Lanre

2017-01-01

Introduction: Surgical extraction of impacted mandibular third molars is often associated with sequelae such as postoperative pain, facial edema, and limitation in mouth opening ability. These sequelae may result in changes in the patients’ lifestyle and quality of life (QoL). Aim: The aim of this study was to evaluate the effect of surgical extraction of impacted mandibular third molars on patients’ QoL in the immediate postoperative period (7 days). Materials and Methods: Ethical approval for this study was obtained from the Health Research and Ethics committee of the Lagos University Teaching Hospital. A total of 124 individuals with impacted mandibular third molars, who satisfied the inclusion criteria and consented to participate in this study, were included. The Oral Health Impact Profile-14 (OHIP-14) QoL questionnaire was used to assess QoL. QoL was assessed preoperatively (baseline) and on postoperative days (PODs) 1, 3, and 7. Maximal interincisal mouth opening, facial width, and pain were also reviewed at all evaluation points. Data analysis was done using the Statistical Package for Social Sciences (SPSS) for Windows (version 16.0, Chicago, IL, USA). Results: A total of 124 individuals were included in the final analysis. An age range of 18–51 years with a mean (±standard deviation) of 28.5 (7.4) years was observed. A male to female ratio of 1:1.5 was observed. The most frequently encountered type of impaction was the mesioangular impaction 51 (41.1%) and recurrent pericoronitis was the principal reason for extraction 53 (42.7%). The severity of the sequelae (pain, trismus, and facial edema) was maximal on the first POD. Patients’ overall QoL deteriorated sharply on the first POD and subsequently improved. Conclusion: Surgical extraction of mandibular third molars is associated with worsening of patients’ postoperative QoL in the immediate postoperative period. Prospective patients should be informed about this, and ways of reducing this untoward effect should be explored. PMID:29326504

Taking advantage of an unerupted third molar: a case report.

PubMed

Pereira, Igor Figueiredo; Santiago, Fernando Zander Mucci; Sette-Dias, Augusto Cesar; Noronha, Vladimir Reimar Augusto de Souza

2017-01-01

Treatments with dental surgery seek to displace tooth to the correct position within the dental arch. To report a clinical case that took advantage of an unerupted third molar. A male patient, 18 years of age, was referred by his dentist to evaluate the third molars. The clinical exam revealed no visible lower third molars. The computed tomography (CT) exam showed the presence of a supernumerary tooth in the region of the mandibular ramus, on the left side, and impaction of the third molar, which was causing root resorption on the second molar, thus making it impossible to remain in the buccal cavity. The preferred option, therefore, was to remove both second molar and the supernumerary tooth, in addition to attaching a device to the third molar during surgery for further traction. After 12 months, the third molar reached the proper position. When a mandibular second permanent molar shows an atypical root resorption, an impacted third molar can effectively substitute the tooth by using an appropriate orthodontic-surgical approach.

Bilateral maxillary fused second and third molars: a rare occurrence

PubMed Central

Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

2012-01-01

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months. PMID:23222992

Bilateral maxillary fused second and third molars: a rare occurrence.

PubMed

Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

2012-12-01

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months.

Endodontic management of a mandibular third molar fused with a fourth molar.

PubMed

Turell, I L; Zmener, O

1999-05-01

Developmental anomalies in permanent molars frequently require surgical intervention. A case of a mandibular third molar fused with a fourth molar which was successfully treated with conservative endodontic therapy is reported.

Digitized morphometric analysis of dental pulp of permanent mandibular second molar for age estimation of Davangere population.

PubMed

Kumar, Nerella Narendra; Panchaksharappa, Mamatha Gowda; Annigeri, Rajeshwari G

2016-04-01

The aim of the present study is to estimate the age of Davangere population by evaluating the pulp to tooth area ratio (PTR) by using digitized intraoral periapical radiographs of permanent mandibular second molar. 400 intraoral periapical radiograph (IOPA) of permanent mandibular 2nd molar of both the sexes aged 14-60 years were used. Digital camera was used to image the radiographs. Images were computed and PTR was calculated by AUTOCAD software. Intra and Inter observer variability was also assessed. Regression analysis was used to estimate the age of an individual by taking PTR as dependent variable. The mean PTR of males and females was 0.10 ± 0.02 and 0.09 ± 0.02 respectively. Negative correlation was observed, when age was compared with PTR {r = -0.441, -0.406 & -0.419 among males, females and total subjects (p < 0.001)}. Regression analysis showed a Standard Error of Estimate (SEE) of 12 years. The Kappa coefficient value for the intra and inter examiner variability was 0.85 & 0.83 respectively. Our results showed that permanent mandibular 2(nd) molar can be taken as an index tooth for estimating the age of the adults using digitized periapical radiograph and AUTOCAD software. Also high differences were observed between estimated and chronological age of 12 years which is not in the acceptable range. But it provides a new window for research in the forensic sciences in estimating the adult age. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques.

PubMed

Abu-Alhaija, Elham; Jaradat, Mohammad; Alwahadni, Ahed

2017-03-01

Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18% hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes. The bond strength testing was performed using a computer control electromechanical universal testing machine. The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and 13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and the addition of silane (group 4) produced bond strength values comparable to the control. Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups. Key words: Molar, shear strength, tensile strength, orthodontic appliances.

An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques

PubMed Central

Alwahadni, Ahed

2017-01-01

Background Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. Material and Methods The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18% hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes. The bond strength testing was performed using a computer control electromechanical universal testing machine. Results The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and 13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and the addition of silane (group 4) produced bond strength values comparable to the control. Conclusions Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups. Key words:Molar, shear strength, tensile strength, orthodontic appliances. PMID:28298990

Relationship between mandibular condyle and angle fractures and the presence of mandibular third molars.

PubMed

Mah, Deuk-Hyun; Kim, Su-Gwan; Moon, Seong-Yong; Oh, Ji-Su; You, Jae-Seek

2015-02-01

We retrospectively evaluated the impact of mandibular third molars on the occurrence of angle and condyle fractures. This was a retrospective investigation using patient records and radiographs. The sample set consisted of 440 patients with mandibular fractures. Eruption space, depth and angulation of the third molar were measured. Of the 144 angle fracture patients, 130 patients had third molars and 14 patients did not. The ratio of angle fractures when a third molar was present (1.26 : 1) was greater than when no third molar was present (0.19 : 1; odds ratio, 6.58; P<0.001). Of the 141 condyle fractures patients, the third molar was present in 84 patients and absent in 57 patients. The ratio of condyle fractures when a third molar was present (0.56 : 1) was lower than when no third molar was present (1.90 : 1; odds ratio, 0.30; P<0.001). The increased ratio of angle fractures with third molars and the ratio of condyle fractures without a third molar were statistically significant. The occurrence of angle and condyle fractures was more affected by the continuity of the cortical bone at the angle than by the depth of a third molar. These results demonstrate that a third molar can be a determining factor in angle and condyle fractures.

The influence of premature loss of temporary upper molars on permanent molars.

PubMed

Cernei, E R; Maxim, Dana Cristiana; Zetu, Irina Nicoleta

2015-01-01

Premature loss of primary molars due to dental caries and their complications has been associated with space loss and eruptive difficulties, especially when the loss occurs early. The aim of our study was to determine the impact of premature loss of temporary upper molars upon the longitudinal axis of the first and second upper permanent molar. The study group included 64 patients 6-9 years old with premature loss of primary molars and a control group of 48 patients with intact temporary teeth. It was evaluated the angle between longitudinal axis of first and second upper permanent molars and occlusal plane. The sofware used is Easy Dent 4 Viewer®.The data were analyzed by using the Statistical Package for the Social Sciences (version 20.0; SPSS, Chicago, III). It was observed that premature loss of upper second deciduous molars modifies greater the vertical axis of the permanent molars than the premature loss of first upper primary molar. First upper primary molar loss cause an acceleration eruption of first premolar, which will produce a distal inclintion of the both permanent molars. The use of space maintainers after premature loss of the second upper temporary molar is a last solution in preventing tridimensional lesions in the dental arch and occlusion.

Pattern of mandibular third molar impaction and its association to caries in mandibular second molar: A clinical variant.

PubMed

Prajapati, V K; Mitra, Ruchi; Vinayak, K M

2017-01-01

Caries in second molar is common and prophylactic removal of the impacted teeth may be considered appropriate. Caries detection and restoration can be difficult and a restored second molar can undergo recurrent caries if the third molar is not removed prophylactically. In this study, the clinical findings related to impaction and its association with angular position and depth of impacted third molar were evaluated. A retrospective descriptive study was carried out among the patients visiting the outpatient, department of Dentistry, RIMS, Ranchi. The clinical examination, periapical radiographs and Pre-op OPG were taken. Teeth positions were analyzed by Pell and Gregory and Winter classification. The angulation and depth of mandibular third molar impaction and caries in the second molar with the eruption status of the mandibular third molar was determined. A total of 200 patients were included in the study between age group 17-45 years. Majority of the Patients reported to the hospital with complaints of decayed tooth (66%) and pain (59%). The most common third molar impaction was mesioangular followed by distoangular. A statistically highly significant difference ( P = 0.001) was obtained with the presence of caries in second molar adjacent to mesioangular third molar in class I and level B. According to this study, pattern of mandibular third molar impaction is in association to caries in mandibular second molar. More future studies are needed. In addition, the results of the present study can be used to screen and inform the patients about the possibility of caries in relation to third molar mandibular impaction.

Use of cone-beam computed tomography to evaluate root and canal morphology of mandibular first and second molars in Turkish individuals

PubMed Central

Sekerci, Ahmet E.; Dinçer, Asiye N.; Cayabatmaz, Muhammed; Zorba, Yahya O.

2013-01-01

Objective: The aim of this study was to investigate the root and canal morphology of mandibular first and second molars in a Turkish population by using cone beam computed tomography (CBCT). Study design: CBCT images of mandibular first (n = 823) and second molar (n = 925) teeth from 605 Turkish patients were analyzed. The root canal configurations were classified according to the method of Vertucci. Results: The majority of mandibular molars (95.8% of first molars, 85.4% of second molars) had two separate roots; however, three roots were identified in 2.06% of first molars and 3.45% of second molars. C-shaped canals occurred 0.85% of first molars and 4.1% of second molars. Three canals were found in 79.9% of first molars and 72.8% of second molars. Most distal roots had a simple type I configuration, whereas mesial roots had more complex canal systems, with more than one canal. The most common root morphology of first and second molars is the two rooted morphology with three canals. Both the mesial and distal roots showed wide variations in canal anatomy with type IV and type I canal configuration predominating in the mesial and distal roots, respectively. Conclusion: Vertucci type I and IV canal configurations were the most prevalent in the distal and mesial roots, respectively, of both the mandibular first and second permanent molar teeth. Key words:Cone-beam CT, Turkish, mandibular molars, root and canal morphology. PMID:23524421

Investigation of cloud condensation nuclei properties and droplet growth kinetics of the water-soluble aerosol fraction in Mexico City

NASA Astrophysics Data System (ADS)

Padró, Luz T.; Tkacik, Daniel; Lathem, Terry; Hennigan, Chris J.; Sullivan, Amy P.; Weber, Rodney J.; Huey, L. Greg; Nenes, Athanasios

2010-05-01

We present hygroscopic and cloud condensation nuclei (CCN) relevant properties of the water-soluble fraction of Mexico City aerosol collected upon filters during the 2006 Megacity Initiative: Local and Global Research Observations (MILAGRO) campaign. Application of κ-Köhler theory to the observed CCN activity gave a fairly constant hygroscopicity parameter (κ = 0.28 ± 0.06) regardless of location and organic fraction. Köhler theory analysis was used to understand this invariance by separating the molar volume and surfactant contributions to the CCN activity. Organics were found to depress surface tension (10-15%) from that of pure water. Daytime samples exhibited lower molar mass (˜200 amu) and surface tension depression than nighttime samples (˜400 amu); this is consistent with fresh hygroscopic secondary organic aerosol (SOA) condensing onto particles during peak photochemical hours, subsequently aging during nighttime periods of high relative humidity. Changes in surface tension partially compensate for shifts in average molar volume to give the constant hygroscopicity observed, which implies the amount (volume fraction) of soluble material in the parent aerosol is the key composition parameter required for CCN predictions. This finding, if applicable elsewhere, may explain why CCN predictions are often found to be insensitive to assumptions of chemical composition and provides a very simple way to parameterize organic hygroscopicity in atmospheric models (i.e., κorg = 0.28ɛWSOC). Special care should be given, however, to surface tension depression from organic surfactants, as its nonlinear dependence with organic fraction may introduce biases in observed (and predicted) hygroscopicity. Finally, threshold droplet growth analysis suggests the water-soluble organics do not affect activation kinetics.

Regenerative Needs Following Alveolar Ridge Preservation Procedures in Compromised and Noncompromised Extraction Sockets: A Cone Beam Computed Tomography Study.

PubMed

Koutouzis, Theofilos; Lipton, David

2016-01-01

The aim of this study was to evaluate the necessity for additional regenerative procedures following healing of compromised and noncompromised extraction sockets with alveolar ridge preservation procedures through the use of virtual implant imaging software. The cohort was comprised of 87 consecutive patients subjected to a single maxillary tooth extraction with an alveolar ridge preservation procedure for subsequent implant placement. Patients were divided into two main groups based on the integrity of the buccal bone plate following teeth extraction. Patients in the compromised socket (CS) group (n = 52) had partial or complete buccal bone plate loss, and patients in the noncompromised socket (NCS) group (n = 35) exhibited no bone loss of their socket walls following tooth extraction. Following 4 to 6 months of healing, all patients had a cone beam computed tomography (CBCT) study. Root-formed implants were placed virtually in an ideal prosthetic position. The number of implants per group and location (anterior, premolar, molar) exhibiting exposed buccal implant surface was calculated. In the CS group, 5 out of 19 anterior implants (26.3%), 4 out of 14 premolar implants (28.5%), and 7 out of 19 molar implants (36.8%) had exposed buccal surfaces. In the NCS group, 4 out of 9 anterior implants (44.4%), 2 out of 9 premolar implants (22.2%), and 4 out of 17 molar implants (23.5%) had exposed buccal surfaces. There were no statistically significant differences for intragroup and intergroup comparisons (χ² test, P > .05). This study failed to find statistically significant differences in the frequency of implants with exposed buccal surfaces placed virtually, following treatment of compromised and noncompromised sockets. A high proportion (22% to 44%) of sites had implants that potentially needed additional regenerative procedures.

PCDD/Fs' suppression by sulfur-amine/ammonium compounds.

PubMed

Fu, Jian-Ying; Li, Xiao-Dong; Chen, Tong; Lin, Xiao-Qing; Buekens, Alfons; Lu, Sheng-Yong; Yan, Jian-Hua; Cen, Ke-Fa

2015-03-01

Three distinct -S and -NH2 or NH4(+) containing compounds, including ammonium thiosulfate, aminosulfonic acid and thiourea, were studied as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) inhibitors. All these three -S and -N containing compounds tested show strong suppression of PCDD/Fs formation, especially for thiourea which has not been studied before. With a (S+N)/Cl molar ratio of only 0.47, thiourea could inhibit 97.3% of PCDD/Fs and even 99.8% of I-TEQ. At an unusually high de novo test temperature (650 °C), the PCDD/Fs' formation was still very low but also the inhibition capacity of thiourea was weak, with an efficiency of 59% for PCDD/Fs when with a (S+N)/Cl molar ratio of 1.40. The results also revealed that the inhibition capability of the combined -S/-NH2 or -S/NH4(+) suppressant was strongly influenced by both the nature of the functional group of nitrogen and the value of the molar ratio (S+N)/Cl. The amine functional group -NH2 tends to be more efficient than ammonium NH4(+) and within a certain range a higher (S+N)/Cl value leads to a higher inhibition efficiency. Moreover, the emission of gases was continuously monitored: the Gasmet results revealed that SO2, HCN and NH3 were the most important decomposition products of thiourea. Thiourea is non-toxic, environment-friendly and can be sprayed into the post-combustion zone in form of powder or aqueous solution. The cost of thiourea at least can be partially compensated by its high inhibition efficiency. Therefore, the application of thiourea in a full-scale incinerator system is promising and encouraging. Copyright © 2014 Elsevier Ltd. All rights reserved.

Gestational trophoblastic neoplasia after spontaneous human chorionic gonadotropin normalization following molar pregnancy evacuation.

PubMed

Braga, Antonio; Maestá, Izildinha; Matos, Michelle; Elias, Kevin M; Rizzo, Julianna; Viggiano, Maurício Guilherme Campos

2015-11-01

To evaluate the risk of gestational trophoblastic neoplasia (GTN) after spontaneous human chorionic gonadotropin normalization in postmolar follow-up. Retrospective chart review of 2284 consecutive cases of hydatidiform mole with spontaneous normalization of hCG following uterine evacuation treated at one of five Brazilian reference centers from January 2002 to June 2013. After hCG normalization, GTN occurred in 10/2284 patients (0.4%; 95% CI 0.2%-0.8%). GTN developed in 9/1424 patients (0.6%; 95% CI 0.3%-1.2%) after a complete hydatidiform mole, in 1/849 patients (0.1%; 95% CI<0.01%-0.7%) after a partial hydatidiform mole, and in 0/13 patients (0%; 95% CI 0%-27%) after a twin molar pregnancy. The median time to GTN diagnosis after hCG normalization was 18months, and no diagnoses were made before six months of postmolar surveillance. Patients who required more than 56days to achieve a normal hCG value had a ten-fold increased risk of developing GTN after hCG normalization (9/1074; 0.8%; 95% CI 0.4%-1.6%) compared to those who reached a normal hCG level in fewer than 56days (1/1210;0.08%; 95% CI<0.01%-0.5%; p=0.008). All patients presented with symptoms at the time of GTN diagnosis. GTN after spontaneous hCG normalization following molar pregnancy is exceedingly rare, and the few patients who do develop GTN after achieving a normal hCG value are likely to be diagnosed after completing the commonly recommended six months of postmolar surveillance. Current recommendations for surveillance after hCG normalization should be revisited. Copyright © 2015 Elsevier Inc. All rights reserved.

The heat capacity of hydrous cordierite above 295 K

NASA Astrophysics Data System (ADS)

Carey, J. William

1993-04-01

The heat capacity of synthetic hydrous cordierite (Mg2Al4Si5O18·nH2O) has been determined by differential scanning calorimetry (DSC) from 295 to 425 K as a function of H2O content. Six samples with H2O contents ranging from 0 to 0.82 per formula unit were examined. The partial molar heat capacity of H2O in cordierite over the measured temperature interval is independent of composition and temperature within experimental uncertainty and is equal to 43.3 ±0.8 J/mol/ K. This value exceeds the molar heat capacity of gaseous H2O by 9.7 J/mol/K, but is significantly smaller than the heat capacity of H2O in several zeolites and liquid H2O. A statistical-mechanical model of the heat capacity of adsorbed gas species (Barrer 1978) is used to extrapolate the heat capacity of hydrous cordierite to temperatures greater than 425 K. In this model, the heat capacity of hydrous cordierite (Crd·nH2O) is represented as follows: Cp(Crd · nH2O) = Cp(Crd)+ n{Cp(H2O, gas)+ R(gas constant)} (1) An examination of calorimetric data for hydrous beryl, analcime, mordenite, and clinoptilolite (Hemingway et al. 1986; Johnson et al. 1982, 1991, 1992) demonstrates the general applicability of the statistical-mechanical model for the extrapolation of heat capacity data of zeolitic minerals. The heat capacity data for cordierite are combined with the data of Carey and Navrotsky (1992) to obtain the molar enthalpy of formation and enthalpy of hydration of hydrous cordierite as a function of temperature.

An orthodontic technique for minimally invasive extraction of impacted lower third molar.

PubMed

Ma, Zhi-Gui; Xie, Qian-Yang; Yang, Chi; Xu, Guang-Zhou; Cai, Xie-Yi; Li, Jie-Yan

2013-08-01

To present a novel orthodontic approach for minimally invasive extraction of impacted mandibular third molars (M3s) close to the inferior alveolar nerve (IAN). Eight patients (8 M3s) requiring extraction of M3s were included in this study; there were 2 cases of horizontal impaction, 4 of mesioangular impaction, and 2 of vertical impaction. Cone-beam computed tomogram showed that the roots of impacted M3s in 2 cases interrupted the cortices of the mandibular canal, and those in the other 6 cases were very close to the IAN. Orthodontic treatment was performed in this study. The crowns of 5 impacted teeth were surgically exposed before the application of the orthodontic device, whereas bonding was performed directly to the occlusal surface of the other 3 M3s, which had partially erupted. The opposing maxillary M3s were removed in 3 cases. One-step orthodontic extraction was applied to vertically impacted M3s and 2-step treatment was applied to horizontally or mesioangularly impacted M3s. Success was defined as the separation of the impacted tooth from the IAN as visualized on cone-beam computed tomogram. After orthodontic treatment, all impacted M3s were extruded and separated from the IAN (mean, 6.6 months; range, 4 to 10 months), without any neurologic consequences. The average time of extraction was 5 minutes. In all 8 cases, new bone formation occurred distal to the adjacent second molar. This orthodontic technique may be a minimally invasive approach for the extraction of impacted M3s adjacent to the IAN, with a decreased risk of paresthesias and with osteoperiodontal advantages. Copyright © 2013 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Solvation molar enthalpies and heat capacities of n-alkanes and n-alkylbenzenes on stationary phases of wide-ranging polarity.

PubMed

Lebrón-Aguilar, Rosa; Quintanilla-López, Jesús Eduardo; Santiuste, José María

2010-12-03

A comparison of the most usual gas chromatographic methods for the calculation of partial molar enthalpies of solvation (Δ(sol)H(o)) has been carried out. Those methods based on the fitting of lnV(g) or ln(k/T) vs. 1/T and ln(k/T) vs. (1/T and the temperature arrangement, T(a)) are the most adequate ones for obtaining Δ(sol)H(o) values. However, the latter is the only reliable option for Δ(sol)H(o) estimation when commercial WCOT capillary columns are used, since in this case the estimation of some variables involved in the V(g) determination is less accurate or even impossible. Consequently, in this paper, Δ(sol)H(o) obtained from ln(k/T) vs. (1/T+T(a)) fitting at 373.15 and 298.15K for n-alkanes and n-alkylbenzenes on 12 commercial capillary columns coated with stationary phases covering the 203-3608 McReynolds polarity range are reported. Moreover, molar heat capacities of solvation at constant pressure (Δ(sol)C(p)(o)) have also been calculated using this method. A clear influence on Δ(sol)H(o) of the type and content of the substitution group in the stationary phase was observed. In addition, a linear relationship of Δ(sol)C(p)(o) with the van der Waals volume of the n-alkanes and the temperature gradient of density of the stationary phase was found. The effect of the size of the hydrocarbon on both thermodynamic variables was also investigated. Copyright © 2010 Elsevier B.V. All rights reserved.

Quantitative analysis of glycerol in dicarboxylic acid-rich cutins provides insights into Arabidopsis cutin structure.

PubMed

Yang, Weili; Pollard, Mike; Li-Beisson, Yonghua; Ohlrogge, John

2016-10-01

Cutin is an extracellular lipid polymer that contributes to protective cuticle barrier functions against biotic and abiotic stresses in land plants. Glycerol has been reported as a component of cutin, contributing up to 14% by weight of total released monomers. Previous studies using partial hydrolysis of cuticle-enriched preparations established the presence of oligomers with glycerol-aliphatic ester links. Furthermore, glycerol-3-phosphate 2-O-acyltransferases (sn-2-GPATs) are essential for cutin biosynthesis. However, precise roles of glycerol in cutin assembly and structure remain uncertain. Here, a stable isotope-dilution assay was developed for the quantitative analysis of glycerol by GC/MS of triacetin with simultaneous determination of aliphatic monomers. To provide clues about the role of glycerol in dicarboxylic acid (DCA)-rich cutins, this methodology was applied to compare wild-type (WT) Arabidopsis cutin with a series of mutants that are defective in cutin synthesis. The molar ratio of glycerol to total DCAs in WT cutins was 2:1. Even when allowing for a small additional contribution from hydroxy fatty acids, this is a substantially higher glycerol to aliphatic monomer ratio than previously reported for any cutin. Glycerol content was strongly reduced in both stem and leaf cutin from all Arabidopsis mutants analyzed (gpat4/gpat8, att1-2 and lacs2-3). In addition, the molar reduction of glycerol was proportional to the molar reduction of total DCAs. These results suggest "glycerol-DCA-glycerol" may be the dominant motif in DCA-rich cutins. The ramifications and caveats for this hypothesis are presented. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Petition for Partial Supplemental Waiver of the 2016 Cellulosic Biofuel Volumetric Requirements

EPA Pesticide Factsheets

January 13, 2017, EPA sent a letter to the American Petrochemical and Fuel Manufacturers (“AFPM”) denying its petition for a partial supplemental waiver of the 2016 cellulosic biofuel standard established under the Renewable Fuel Standard.

Positional changes of the third molar in orthodontically treated patients.

PubMed

Mihai, A M; Lulache, I R; Grigore, R; Sanabil, A S; Boiangiu, S; Ionescu, E

2013-06-15

Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions. This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured. Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student's t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions.

Relationship between mandibular condyle and angle fractures and the presence of mandibular third molars

PubMed Central

Mah, Deuk-Hyun; Moon, Seong-Yong; Oh, Ji-Su; You, Jae-Seek

2015-01-01

Objectives We retrospectively evaluated the impact of mandibular third molars on the occurrence of angle and condyle fractures. Materials and Methods This was a retrospective investigation using patient records and radiographs. The sample set consisted of 440 patients with mandibular fractures. Eruption space, depth and angulation of the third molar were measured. Results Of the 144 angle fracture patients, 130 patients had third molars and 14 patients did not. The ratio of angle fractures when a third molar was present (1.26 : 1) was greater than when no third molar was present (0.19 : 1; odds ratio, 6.58; P<0.001). Of the 141 condyle fractures patients, the third molar was present in 84 patients and absent in 57 patients. The ratio of condyle fractures when a third molar was present (0.56 : 1) was lower than when no third molar was present (1.90 : 1; odds ratio, 0.30; P<0.001). Conclusion The increased ratio of angle fractures with third molars and the ratio of condyle fractures without a third molar were statistically significant. The occurrence of angle and condyle fractures was more affected by the continuity of the cortical bone at the angle than by the depth of a third molar. These results demonstrate that a third molar can be a determining factor in angle and condyle fractures. PMID:25741462

[Lead adsorption and arsenite oxidation by cobalt doped birnessite].

PubMed

Yin, Hui; Feng, Xiong-Han; Qiu, Guo-Hong; Tan, Wen-Feng; Liu, Fan

2011-07-01

In order to study the effects of transition metal ions on the physic-chemical properties of manganese dioxides as environmental friendly materials, three-dimensional nano-microsphere cobalt-doped birnessite was synthesized by reduction of potassium permanganate by mixtures of concentrated hydrochloride and cobalt (II) chloride. Powder X-ray diffraction, chemical analysis, N2 physical adsorption, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectra (XPS) were used to characterize the crystal structure, chemical composition and micro-morphologies of products. In the range of molar ratios from 0.05 to 0.20, birnessite was fabricated exclusively. It was observed that cobalt incorporated into the layers of birnessite and had little effect on the crystal structure and micromorpholgy, but crystallinity decreased after cobalt doping. Both chemical analysis and XPS results showed that manganese average oxidation state decreased after cobalt doping, and the percentage of Mn3+ increased. Co(III) OOH existed mainly in the structure. With the increase of cobalt, hydroxide oxygen percentage in molar increased from 12.79% for undoped birnessite to 13.05%, 17.69% and 17.79% for doped samples respectively. Adsorption capacity for lead and oxidation of arsenite of birnessite were enhanced by cobalt doping. The maximum capacity of Pb2+ adsorption increased in the order HB (2 538 mmol/kg) < CoB5 (2798 mmol/kg) < CoB10 (2932 mmol/kg) < CoB20 (3 146 mmol/kg). Oxidation percentage of arsenite in simulated waste water by undoped birnessite was 76.5%, those of doped ones increased by 2.0%, 12.8% and 18.9% respectively. Partial of Co3+ substitution for Mn4+ results in the increase of negative charge of the layer and the content of hydroxyl group, which could account for the improved adsorption capacity of Pb2+. After substitution of manganese by cobalt, oxidation capacity of arsenite by birnessite increases likely due to the higher standard redox potential of Co3+/Co2+ than those of Mn4+/Mn3+/Mn2+. Therefore, Co-doped birnessite is more applicable for the remediation of water polluted with heavy metal ions, implying new methods of modification of manganese dioxides in practice.

Root and Root Canal Morphology of Human Third Molar Teeth.

PubMed

Mohammadi, Zahed; Jafarzadeh, Hamid; Shalavi, Sousan; Bandi, Shilpa; Patil, Shankargouda

2015-04-01

Successful root canal treatment depends on having comprehensive information regarding the root(s)/canal(s) anatomy. Dentists may have some complication in treatment of third molars because the difficulty in their access, their aberrant occlusal anatomy and different patterns of eruption. The aim of this review was to review and address the number of roots and root canals in third molars, prevalence of confluent canals in third molars, C-shaped canals, dilaceration and fusion in third molars, autotransplantation of third molars and endodontic treatment strategies for third molars.

Prevalence of Distal Caries in Mandibular Second Molar Due to Impacted Third Molar

PubMed Central

Alshahrani, Fatima Saeed; Alabsi, Wejdan Saad; Alqahtani, Zainab Ali; Hameed, Mohammad Shahul; Mustafa, Abdel Bagi; Alam, Tanveer

2017-01-01

Introduction A tooth is said to be impacted if it does not reach the occlusal plane even after two-thirds root formation. The aetiology of impacted teeth is varied and multi-factorial. Significant problems associated with impacted teeth include trismus, infection, cervical caries of second molars. Aim This study was aimed to assess the prevalence of distal caries in second molar teeth due to impacted third molars and to compare with similar studies conducted elsewhere. Materials and Methods Study included assessment of patients reporting between 2009 to 2014 for dental care at College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia. This is a retrospective cross-sectional study which included a total of 6000 Orthopantomograms (OPGs). The data collected was decoded and entered into excel spread sheet. Descriptive analysis of the data was done and results were displayed as frequency table and graphs. Results A total of 979 patients had impacted third molars (16.31%). A total of 39% patient’s with impacted third molars had distal cervical caries in second molar. Mesioangular impaction was the most prominent type. This was closely followed by horizontal impaction causing distal caries in second molars. Age group between 21-28 years and male gender had the higher prevalence of distal caries in second molar teeth due to impacted third molars. Conclusion A total of 39% of the patients with impacted mandibular third molars had distal cervical caries in second molars. Mesioangular type, male gender, age group 21-28 years were the prominent factors associated with distal caries in second molar teeth due to impacted third molars. PMID:28511504

Pattern of mandibular third molar impaction and its association to caries in mandibular second molar: A clinical variant

PubMed Central

Prajapati, V. K.; Mitra, Ruchi; Vinayak, K. M.

2017-01-01

Background: Caries in second molar is common and prophylactic removal of the impacted teeth may be considered appropriate. Caries detection and restoration can be difficult and a restored second molar can undergo recurrent caries if the third molar is not removed prophylactically. In this study, the clinical findings related to impaction and its association with angular position and depth of impacted third molar were evaluated. Materials and Methods: A retrospective descriptive study was carried out among the patients visiting the outpatient, department of Dentistry, RIMS, Ranchi. The clinical examination, periapical radiographs and Pre-op OPG were taken. Teeth positions were analyzed by Pell and Gregory and Winter classification. The angulation and depth of mandibular third molar impaction and caries in the second molar with the eruption status of the mandibular third molar was determined. Results: A total of 200 patients were included in the study between age group 17-45 years. Majority of the Patients reported to the hospital with complaints of decayed tooth (66%) and pain (59%). The most common third molar impaction was mesioangular followed by distoangular. A statistically highly significant difference (P = 0.001) was obtained with the presence of caries in second molar adjacent to mesioangular third molar in class I and level B. Conclusion: According to this study, pattern of mandibular third molar impaction is in association to caries in mandibular second molar. More future studies are needed. In addition, the results of the present study can be used to screen and inform the patients about the possibility of caries in relation to third molar mandibular impaction. PMID:28584538

[Effects of the first premolar extraction on the third molar angulation].

PubMed

He, Yu-hong; Duan, Yin-zhong; Pan, Ji-jun; Xi, Lan-lan

2008-08-01

To analyze the effects about inclinations of the second and the third molars in patients treated with or without premolar extractions. Fifty-six adolescents were chosen and divided into the first premolar extraction and non-extraction groups, 30 and 26 patients respectively. The pre-treatment and post-treatment panoramic radiographs were made. Angles between long axis of the third molar and the occlusal plane (the second molar alike), and long axis of the second and the third molar were measured and evaluated. The maxillary and mandibular third molar angulations were all improved after treatment in two groups. Compared with non-extraction group, the average changes of angle between long axis of the third molar and the occlusal plane increased significantly in maxilla and mandible (P < 0.05). Average changes of angles between long axis of the second and the third molar decreased and had statistically significant difference (P < 0.05). The change of angle between long axis of mandibular second molar and the occlusal plane had statistically significant difference (P < 0.05), but there was no statistically significant difference in maxillary second molar (P > 0.05). The first premolar extraction in orthodontic treatment could improve the third molar angulations and it would promote the eruption of the third molar.

Risk of osteoradionecrosis after extraction of impacted third molars in irradiated head and neck cancer patients.

PubMed

Oh, Hee-Kyun; Chambers, Mark S; Garden, Adam S; Wong, Pei-Fong; Martin, Jack W

2004-02-01

This study was performed to compare the risk of osteoradionecrosis (ORN) in head and neck cancer patients in whom 1 or more impacted third molars were extracted before radiotherapy with patients whose impacted third molars were left intact. Eighty-one patients were selected from the medical records from 1989 to 1998. Patients had at least 1 impacted third molar and received radiotherapy for a head and neck cancer. These patients were divided into 2 groups on the basis of preirradiation extraction: group 1, patients who had impacted third molars extracted before radiotherapy (n = 55), and group 2, patients whose impacted third molars were left intact before radiotherapy (n = 38). In 12 patients of combined groups 1 and 2, at least 1 but not all of the impacted third molars were extracted before radiotherapy. Before radiotherapy, a total of 99 impacted third molars were extracted from the 55 patients in group 1 and a total of 55 impacted third molars were left intact in the 38 patients in group 2. After radiotherapy, a total of 7 impacted third molars were removed from 5 patients as treatment for infection (5 lower molars) or discomfort (2 upper molars). A total of 4 patients (2 from group 1 and 2 from group 2) developed ORN in the mandible. Of these 4 cases of ORN, 1 from group 1 appeared to be related to a dry socket that developed after preirradiation extraction of a lower impacted third molar, 1 from group 2 seemed to be related to infection of a lower impacted third molar after radiotherapy, and the remaining 2 cases appeared to be unrelated to an impacted third molar. Because few patients in this study developed ORN, the study failed to demonstrate whether preirradiation extraction versus retention of impacted third molars affects the risk for ORN.

Analysis of body mass index, the mandible, and dental alveolar arch factors in prediction of mandibular third molar impaction: a pilot study.

PubMed

Akinbami, Babatunde O; Didia, Blessing C

2010-12-01

The aim of this study was to determine how some physical characteristics can be used to predict the occurrence of impacted mandibular third molars. While the concept of prophylactic removal of the asymptomatic erupting or impacted mandibular third molar has generated much controversy over the years, new theories of therapeutic surgical removal of the erupting tooth and therapeutic agenesis of the tooth bud are emerging. However, there are a few studies that address the anthropometric factors that could predict an impacted mandibular third molar. The study included Nigerian patients of both genders who were at least 16 years of age. A total of 83 subjects participated in the study; there were 44 (53 percent) females and 39 (47 percent) males. Eighty-one (97.6 percent) of the participants were between 16 and 23 years old, while 2 (2.4 percent) were between 30 and 39 years old, of which 44 (53 percent) were women and 39 (47 percent) were men. There were 38 (45.8 percent) cases of impaction and 45 (54.2 percent) cases of unimpacted third molar. The mean and standard deviation values of BMI for the two groups in males and females were 21.10±1.90, 22.40±2.70 and 22.00±2.40, 22.30±1.99 respectively, with no significant difference, p>0.05, CI 95%. The two determinant factors of impaction were mandibular length and the difference between alveolar arch length (p=0.04) and total teeth size. Both of these variables had significant inverse correlations with impaction values of p=0.04 and p=0.003, respectively. The prediction values were 59 percent for mandibular length and 81.9 percent for differences between mandibular length and teeth sizes, respectively. The synthesized prediction value by the two determinant factors is 75.6 percent.The subjects were divided into two categories: presence of impaction (Group 1) and absence of impaction (Group 2). Impaction of the mandibular third molar was assessed by clinical and radiographic evaluation. Body mass index (BMI) of each subject was determined by measuring the body weight (BW) and body height (BH), then dividing the weight of the body by the square of the height. The mandibular index (MI) was assessed by measuring the length and width of the mandible (MW). It was calculated by dividing the width of the mandible by the length of the mandible. The mandibular length (ML) consisted of the total teeth sizes of the three anterior teeth, the two premolars, and the first and second molars. These dimensions were measured with a divider/ruler and recorded. The anterior-posterior distance of the arch from the midline to the retromolar pad (alveolar arch length) also was measured. The prediction of mandibular third molar impaction was mainly dependent on two factors: the length of the mandible and the difference between arch length and total teeth size. Small mandible, small dental arch, and large teeth are risk factors that are strongly associated with the occurrence of impacted third molars.

Vapor pressures, thermodynamic stability, and fluorescence properties of three 2,6-alkyl naphthalenes.

PubMed

Santos, Ana Filipa L O M; Oliveira, Juliana A S A; Ribeiro da Silva, Maria D M C; Monte, Manuel J S

2016-03-01

This work reports the experimental determination of relevant thermodynamic properties and the characterization of luminescence properties of the following polycyclic aromatic hydrocarbons (PAHs): 2,6-diethylnaphthalene, 2,6-diisopropylnaphthalene and 2,6-di-tert-butylnaphthalene. The standard (p(o) = 0.1 MPa) molar enthalpies of combustion, ΔcHm(o), of the three compounds were determined using static bomb combustion calorimetry. The vapor pressures of the crystalline phase of 2,6-diisopropylnaphthalene and 2,6-di-tert-butylnaphthalene were measured at different temperatures using the Knudsen effusion method and the vapor pressures of both liquid and crystalline phases of 2,6-diethylnaphthalene were measured by means of a static method. The temperatures and the molar enthalpies of fusion of the three compounds were determined using differential scanning calorimetry. The gas-phase molar heat capacities and absolute entropies of the three 2,6-dialkylnaphthalenes studied were determined computationally. The thermodynamic stability of the compounds in both the crystalline and gaseous phases was evaluated by the determination of the Gibbs energies of formation and compared with the ones reported in the literature for 2,6-dimethylnaphthalene. From fluorescence spectroscopy measurements, the optical properties of the compounds studied and of naphthalene were evaluated in solution and in the solid state. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Influence of Dimensionality on Estimation in the Partial Credit Model.

ERIC Educational Resources Information Center

De Ayala, R. J.

1995-01-01

The effect of multidimensionality on partial credit model parameter estimation was studied with noncompensatory and compensatory data. Analysis results, consisting of root mean square error bias, Pearson product-moment corrections, standardized root mean squared differences, standardized differences between means, and descriptive statistics…

Experience with the use of a partial ossicular replacement prosthesis with a ball-and-socket joint between the plate and the shaft.

PubMed

Birk, Stephanie; Brase, Christoph; Hornung, Joachim

2014-08-01

In the further development of alloplastic prostheses for use in middle ear surgery, the Dresden and Cologne University Hospitals, working together with a company, introduced a new partial ossicular replacement prosthesis in 2011. The ball-and-socket joint between the prosthesis and the shaft mimics the natural articulations between the malleus and incus and between the incus and stapes, allowing reaction to movements of the tympanic membrane graft, particularly during the healing process. Retrospective evaluation To reconstruct sound conduction as part of a type III tympanoplasty, partial ossicular replacement prosthesis with a ball-and-socket joint between the plate and the shaft was implanted in 60 patients, with other standard partial ossicular replacement prosthesis implanted in 40 patients and 64 patients. Pure-tone audiometry was carried out, on average, 19 and 213 days after surgery. Results of the partial ossicular replacement prosthesis with a ball-and-socket joint between the plate and the shaft were compared with those of the standard prostheses. Early measurements showed a mean improvement of 3.3 dB in the air-bone gap (ABG) with the partial ossicular replacement prosthesis with a ball-and-socket joint between the plate and the shaft, giving similar results than the standard implants (6.6 and 6.0 dB, respectively), but the differences were not statistically significant. Later measurements showed a statistically significant improvement in the mean ABG, 11.5 dB, compared with 4.4 dB for one of the standard partial ossicular replacement prosthesis and a tendency of better results to 6.9 dB of the other standard prosthesis. In our patients, we achieved similarly good audiometric results to those already published for the partial ossicular replacement prosthesis with a ball-and-socket joint between the plate and the shaft. Intraoperative fixation posed no problems, and the postoperative complication rate was low.

Metal-organic complexes in geochemical processes: Estimation of standard partial molal thermodynamic properties of aqueous complexes between metal cations and monovalent organic acid ligands at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Shock, Everetr L.; Koretsky, Carla M.

1995-04-01

Regression of standard state equilibrium constants with the revised Helgeson-Kirkham-Flowers (HKF) equation of state allows evaluation of standard partial molal entropies ( overlineSo) of aqueous metal-organic complexes involving monovalent organic acid ligands. These values of overlineSo provide the basis for correlations that can be used, together with correlation algorithms among standard partial molal properties of aqueous complexes and equation-of-state parameters, to estimate thermodynamic properties including equilibrium constants for complexes between aqueous metals and several monovalent organic acid ligands at the elevated pressures and temperatures of many geochemical processes which involve aqueous solutions. Data, parameters, and estimates are given for 270 formate, propanoate, n-butanoate, n-pentanoate, glycolate, lactate, glycinate, and alanate complexes, and a consistent algorithm is provided for making other estimates. Standard partial molal entropies of association ( Δ -Sro) for metal-monovalent organic acid ligand complexes fall into at least two groups dependent upon the type of functional groups present in the ligand. It is shown that isothermal correlations among equilibrium constants for complex formation are consistent with one another and with similar correlations for inorganic metal-ligand complexes. Additional correlations allow estimates of standard partial molal Gibbs free energies of association at 25°C and 1 bar which can be used in cases where no experimentally derived values are available.

Cervicofacial subcutaneous air emphysema after dental extraction.

PubMed

Reznick, J B; Ardary, W C

1990-04-01

A patient was seen by a general practitioner for surgical removal of his third molar. A standard high-speed handpiece was used to remove the tooth. During the procedure, subcutaneous emphysema developed. Later the same day, the patient's swelling increased and his airway was compromised. The patient's condition, the differential diagnosis, etiological factors, and treatment of this condition are all detailed within this clinical report.

Contribution of acidic components to the total acid number (TAN) of bio-oil

DOE PAGES

Park, Lydia K-E.; Liu, Jiaojun; Yiacoumi, Sotira; ...

2017-03-28

Bio-oil or pyrolysis oil — a product of thermochemical decomposition of biomass under oxygen-limited conditions — holds great potential to be a substitute for nonrenewable fossil fuels. But, its high acidity, which is primarily due to the degradation of hemicelluloses, limits its applications. For the evaluation of bio-oil production and treatment, it is essential to accurately measure the acidity of bio-oil. The total acid number (TAN), which is defined as the amount of potassium hydroxide needed to titrate one gram of a sample and has been established as an ASTM method to measure the acidity of petroleum products, has beenmore » employed to investigate the acidity of bio-oil. The TAN values of different concentrations of bio-oil components such as standard solutions of acetic acid, propionic acid, vanillic acid, hydroxybenzoic acid, syringic acid, hydroxymethylfurfural, and phenol were analyzed according to the ASTM D664 standard method. Our method showed the same linear relationship between the TAN values and the molar concentrations of acetic, propionic, and hydroxybenzoic acids. A different linear relationship was found for vanillic acid, due to the presence of multiple functional groups that can contribute to the TAN value. Furthermore, the influence of the titration solvent on the TAN values has been determined by comparing the TAN values and titration curves obtained from the standard method with results from the TAN analysis in aqueous environment and with equilibrium modeling results. Aqueous bio-oil samples with a known amount of acetic acid added were also analyzed. The additional acetic acid in bio-oil samples caused a proportional increase in the TAN values. These results of this research indicate that the TAN value of a sample with acids acting as monoprotic acids in the titration solvent can be converted to the molar concentration of total acids. For a sample containing acids that act as diprotic and polyprotic acids, however, its TAN value cannot be simply converted to the molar concentration of total acids because these acids have a stronger contribution to the TAN values than the contribution of monoprotic acids.« less

Contribution of acidic components to the total acid number (TAN) of bio-oil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Lydia K-E.; Liu, Jiaojun; Yiacoumi, Sotira

Bio-oil or pyrolysis oil — a product of thermochemical decomposition of biomass under oxygen-limited conditions — holds great potential to be a substitute for nonrenewable fossil fuels. But, its high acidity, which is primarily due to the degradation of hemicelluloses, limits its applications. For the evaluation of bio-oil production and treatment, it is essential to accurately measure the acidity of bio-oil. The total acid number (TAN), which is defined as the amount of potassium hydroxide needed to titrate one gram of a sample and has been established as an ASTM method to measure the acidity of petroleum products, has beenmore » employed to investigate the acidity of bio-oil. The TAN values of different concentrations of bio-oil components such as standard solutions of acetic acid, propionic acid, vanillic acid, hydroxybenzoic acid, syringic acid, hydroxymethylfurfural, and phenol were analyzed according to the ASTM D664 standard method. Our method showed the same linear relationship between the TAN values and the molar concentrations of acetic, propionic, and hydroxybenzoic acids. A different linear relationship was found for vanillic acid, due to the presence of multiple functional groups that can contribute to the TAN value. Furthermore, the influence of the titration solvent on the TAN values has been determined by comparing the TAN values and titration curves obtained from the standard method with results from the TAN analysis in aqueous environment and with equilibrium modeling results. Aqueous bio-oil samples with a known amount of acetic acid added were also analyzed. The additional acetic acid in bio-oil samples caused a proportional increase in the TAN values. These results of this research indicate that the TAN value of a sample with acids acting as monoprotic acids in the titration solvent can be converted to the molar concentration of total acids. For a sample containing acids that act as diprotic and polyprotic acids, however, its TAN value cannot be simply converted to the molar concentration of total acids because these acids have a stronger contribution to the TAN values than the contribution of monoprotic acids.« less

Thermally induced gelling of oil-in-water emulsions comprising partially crystallized droplets: the impact of interfacial crystals.

PubMed

Thivilliers, Florence; Laurichesse, Eric; Saadaoui, Hassan; Leal-Calderon, Fernando; Schmitt, Véronique

2008-12-02

We produced triglyceride-in-water emulsions comprising partially crystallized droplets, stabilized by a mixture of protein and low molecular weight surfactant. The emulsions were emulsified in the melted state of the oil phase and stored at low temperature (4 degrees C) right after fabrication to induce oil crystallization. The systems were then warmed to room temperature for a short period of time and cooled again to 4 degrees C. Owing to this treatment referred to as temperature cycling or "tempering", the initially fluid emulsions turned into hard gels. We followed the bulk rheological properties of the materials during and after tempering. The storage modulus, G', exhibited a dramatic increase when tempering was applied. We showed that the systems evolved following two distinct regimes that depend on the average droplet size and on the surfactant-to-protein molar ratio. Gelling may involve partial coalescence of the droplets, i.e., film rupturing with no further shape relaxation because of the solid nature of the droplets. Alternatively, gelling may occur without film rupturing, and is reminiscent of a jamming transition induced by surface roughness. We discussed the origin of these two mechanisms in terms of the properties (size and protuberance) of the interfacial oil crystals.

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

PubMed Central

Souki, Bernardo Q.; Cheib, Paula L.; de Brito, Gabriela M.; Pinto, Larissa S. M. C.

2015-01-01

Maxillary second molar impaction in the adjacent ectopic third molar is a rare condition that practitioners might face in the field of pediatric dentistry and orthodontics. The early diagnosis and extraction of the adjacent ectopic third molar have been advocated, and prior research has reported a high rate of spontaneous eruption following third molar removal. However, some challenges in the daily practice are that the early diagnosis of this type of tooth impaction is difficult with conventional radiographic examination, and sometimes the early surgical removal of the maxillary third molar must be postponed because of the risks of damaging the second molar. The objective of this study is to report a case series of five young patients with maxillary second molar impaction and to discuss the difficulty of early diagnosis with the conventional radiographic examination, and unpredictability of self-correction. PMID:26321848

Maxillary molar intrusion with micro-implant anchorage (MIA).

PubMed

Park, Hyo-Sang; Jang, Bong-Kyu; Kyung, Hee-Moon

2005-11-01

Intrusion of the maxillary molars is difficult to accomplish using traditional methods of anchorage. To describe methods of maxillary molar intrusion with the aid of micro-implants. Micro-implants provide stable intra-oral anchorage and enable the maxillary molars to be intruded without the usual side effects. Three adult patients are presented showing how micro-implants can be used to intrude the maxillary molars. In the first patient micro-implants were placed in the alveolar process between the second premolar and first molar, in the second patient micro-implants were placed in the palatal alveolar process between the first and second molars, and in the third patient a micro-implant was placed in the palate paramedially. A transpalatal bar was used to prevent bucco- or linguoversion of the molars during intrusion. The maxillary molars can be intruded with intra-oral anchorage derived from microscrew implants.

Positional changes of the third molar in orthodontically treated patients

PubMed Central

Mihai, AM; Lulache, IR; Grigore, R; Sanabil, AS; Boiangiu, S; Ionescu, E

2013-01-01

Objective and Rationale. Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions. Method. This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured. Results. Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student’s t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions. PMID:23904878

The indications for third-molar extractions.

PubMed

Steed, Martin B

2014-06-01

Defining the indications for third-molar extraction continues to be a topic of controversy. The dentist's management of third molars commonly hinges on identifying the presence of symptoms or disease that clearly is attributable to the third molar. Use of a guide that serves as a systematic and unambiguous way to classify third molars has been advocated. Patients' symptoms are designated as present and attributable to the third molar (Sx+) or as absent (Sx-). In addition, clinical or radiographic evidence of disease is evaluated and designated as present (D+) or absent (D-). Evidence-based clinical data developed from prospective investigations have shown that an asymptomatic third molar does not necessarily reflect the absence of disease. Current data are not sufficient to refute or support prophylactic extraction versus active surveillance for the routine management of third molars that are asymptomatic and free of disease (group D). Although decisions regarding third-molar management usually are straightforward, the evidence supporting extraction versus retention of asymptomatic disease-free (group D) third molars is lacking. Active surveillance, a prescribed program of follow-up and reassessment at regular intervals are recommended for retained third molars rather than waiting for the onset of symptoms.

Effects of Lower Third Molar Angulation and Position on Lower Arch Crowding.

PubMed

Selmani, Mimoza E; Gjorgova, Julijana; Selmani, Manushaqe E; Shkreta, Mirsad; Duci, Shkelzen B

2016-01-01

The role of the third molars in lower arch crowding has been debated for more than a century. The aim of this study was to determine the relationship between lower arch crowding and the presence of angulation and position of lower third molar. The measurements of the dental arch were made in 120 subjects aged 16 to 21 years, with average age to 18 years. The subjects were divided into two groups: Class I normal occlusion comprised 35 male and 25 female with mean age 18.87years, whereas Class I crowding comprised 27 males and 33 females with mean age 18.5 years. The dental pantomogram (DPT) were used to calculate the ratio of retromolar space (Ganss ratio), angulation of third molar to second molar and third molar to the base of the mandible. The results showed that measurements of Ganss ratio, third molar angulation to the base of the mandible, and third molar to second molar inclination, was statistically significant between crowded and normal groups. It can be concluded that there was a strong relationship between angulation and position of third molars and lower arch crowding. Key words: Third molars, angulation, lower arch, crowding

Patient with oligodontia treated with a miniscrew for unilateral mesial movement of the maxillary molars and alignment of an impacted third molar.

PubMed

Maeda, Aya; Sakoguchi, Yoko; Miyawaki, Shouichi

2013-09-01

This report describes the treatment of a 20-year-old woman with a dental midline deviation and 7 congenitally missing premolars. She had retained a maxillary right deciduous canine and 4 deciduous second molars, and she had an impacted maxillary right third molar. The maxillary right deciduous second molar was extracted, and the space was nearly closed by mesial movement of the maxillary right molars using an edgewise appliance and a miniscrew for absolute anchorage. The miniscrew was removed, and the extraction space of the maxillary right deciduous canine was closed, correcting the dental midline deviation. After the mesial movement of the maxillary right molars, the impacted right third molar was aligned. To prevent root resorption, the retained left deciduous second molars were not aligned by the edgewise appliance. The occlusal contact area and the maximum occlusal force increased over the 2 years of retention. The miniscrew was useful for absolute anchorage for unilateral mesial movement of the maxillary molars and for the creation of eruption space and alignment of the impacted third molar in a patient with oligodontia. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Effect of premolar extraction on mandibular third molar impaction in young adults.

PubMed

Türköz, Cağrı; Ulusoy, Cağrı

2013-07-01

To test the null hypothesis that orthodontic therapy with or without premolar extraction does not result in any difference in third molar impaction. Two groups were formed: 22 patients in one group with first premolar extractions and 22 patients in the other group without extractions. All patients were nongrowing subjects who had normal gonial angles and were skeletal Class I at the beginning of treatment. The available space for third molars, inclination of second and third molars, and angle between the second and third molars were evaluated. Also, the correlation of measured parameters and type of orthodontic therapy with the eruption of third molars was evaluated. Of the third molars, 81.8% were impacted in the nonextraction group and 63.6% were impacted in the extraction group. Impaction of mandibular third molars was significantly correlated to the pretreatment and posttreatment inclination of third molars and the angle between the second and third molars. In the extraction therapy group, the retromolar distance increased significantly with a mean of 1.30 ± 1.25 mm. When the inclination of the third molar is inconvenient, the tooth may remain impacted even if there is enough retromolar space.

The effects of a topical gel containing chitosan, 0,2% chlorhexidine, allantoin and despanthenol on the wound healing process subsequent to impacted lower third molar extraction

PubMed Central

Madrazo-Jiménez, Marta; Rodríguez-Caballero, Ángela; Serrera-Figallo, María-Ángeles; Garrido-Serrano, Roberto; Gutiérrez-Corrales, Aida; Gutiérrez-Pérez, José-Luis

2016-01-01

Background Despite efforts to prevent postoperative discomfort, there are still many immediate side effects associated with the surgical extraction of impacted lower third molars. Cicatrization is a physiological process through which the loss of integrity of oral mucosa is recovered and damaged tissues are repaired. Bexident Post (ISDIN, Spain) is a topical gel that contains chitosan, 0.2% chlorhexidine, allantoin and dexpanthenol. While this gel has many clinical indications, there are no published clinical trials evaluating its use in impacted mandibular third molar surgery. This study aims to clinically evaluate the efficacy of a gel containing chitosan, 0.2% chlorhexidine, allantoin and dexpanthenol on wound healing and reduction of postoperative side effects and complications after extraction of an impacted mandibular third molar. Material and Methods A split-mouth design study was carried out on a total of 50 bilaterally and symmetrically impacted third molar extractions, which were randomly placed into either a control group (CG=25) or an experimental group (EG=25). Patients were all informed of the purpose of the study and provided written consent. All procedures were carried out by the same dental practitioner, in accordance with standard surgical protocol. A different dental practitioner, unaware of which treatment had been applied, provided follow-up care. The EG applied 10 ml of topical gel composed of chitosan, 0.2% chlorhexidine, allantoin and dexpanthenol to the surgical wound three times a day for 10 days, patients in the CG did not apply any gel. Results The groups were homogeneous insofar as potentially confounding variables. No significant findings were found regarding postoperative swelling and pain. Neither of the groups displayed poor healing or infectious complications of the wound during the postoperative period. In all the recorded follow-ups (Day 7 p=0.001, and Day 14 p=0.01), the wound’s aesthetic appearance was better in the EG. Overall treatment tolerance was satisfactory and similar in both groups. Conclusions The gel composed of chitosan, 0.2% chlorhexidine, allantoin and dexpanthenol did not aid in patients’ postoperative comfort; however, improved wound healing was observed. Key words:Impacted lower third molar, postoperative wound healing, chitosan, chlorhexidine, allantoin, dexpanthenol, postoperative period. PMID:27475700

Concentration and density changes at an electrode surface and the principle of unchanging total concentration

DOE PAGES

Stephen W. Feldberg; Lewis, Ernie R.

2016-02-17

In this study, the principle of unchanging total concentration as described by Oldham and Feldberg [J. Phys. Chem. B, 103, 1699 (1999)] is invoked to analyze systems comprising a redox pair (X z1 1 and X z2 2) plus one or more non-electroactive species (X z3 3,X z4 4...X zjmax jmax) where X zj j is the j th species with charge z j and concentration; c j. The principle states that if the diffusion coefficients for all species are identical and mass transport is governed by the Nernst-Planck expression, the total concentration does not change during any electrochemical perturbation,more » i.e.: Σ jmax j=1[X zj j]=Σ jmax j=1 c j = S P With this principle we deduce the electrochemically induced difference between the surface and bulk concentrations for each species. Those concentration differences are translated into density differences which are a function of the density of the solvent and of the concentration differences, molecular masses and the standard partial molar volumes of all species. Those density differences in turn can induce convection that will ultimately modify the observed current. However, we did not attempt to quantify details of the natural convection and current modification produced by those density differences.« less

Application of a chitosan-immobilized Talaromyces thermophilus lipase to a batch biodiesel production from waste frying oils.

PubMed

Romdhane, Ines Belhaj-Ben; Romdhane, Zamen Ben; Bouzid, Maha; Gargouri, Ali; Belghith, Hafedh

2013-12-01

Waste frying oil, which not only harms people's health but also causes environmental pollution, can be a good alternative to partially substitute petroleum diesel through transesterification reaction. This oil contained 8.8 % of free fatty acids, which cause a problem in a base-catalyzed process. In this study, synthesis of biodiesel was efficiently catalyzed by the covalently immobilized Talaromyces thermophilus lipase and allowed bioconversion yield up to 92 % after 24 h of reaction time. The optimal molar ratio was four to six parts of methanol to one part of oil with a biocatalyst loaded of 25 wt.% of oil. Further, experiments revealed that T. thermophilus lipase, immobilized by a multipoint covalent liaison onto activated chitosan via a short spacer (glutaraldehyde), was sufficiently tolerant to methanol. In fact, using the stepwise addition of methanol, no significant difference was observed from the one-step whole addition at the start of reaction. The batch biodiesel synthesis was performed in a fixed bed reactor with a lipase loaded of 10 g. The bioconversion yield of 98 % was attained after a 5-h reaction time. The bioreactor was operated successfully for almost 150 h without any changes in the initial conversion yield. Most of the chemical and physical properties of the produced biodiesel meet the European and USA standard specifications of biodiesel fuels.

Structure-activity correlation in transfection promoted by pyridinium cationic lipids.

PubMed

Parvizi-Bahktar, P; Mendez-Campos, J; Raju, L; Khalique, N A; Jubeli, E; Larsen, H; Nicholson, D; Pungente, M D; Fyles, T M

2016-03-21

The efficiency of the transfection of a plasmid DNA encoding a galactosidase promoted by a series of pyridinium lipids in mixtures with other cationic lipids and neutral lipids was assessed in CHO-K1 cells. We identify key molecular parameters of the lipids in the mixture - clog P, lipid length, partial molar volume - to predict the morphology of the lipid-DNA lipoplex and then correlate these same parameters with transfection efficiency in an in vitro assay. We define a Transfection Index that provides a linear correlation with normalized transfection efficiency over a series of 90 different lipoplex compositions. We also explore the influence of the same set of molecular parameters on the cytotoxicity of the formulations.

Continuous-flow free acid monitoring method and system

DOEpatents

Strain, J.E.; Ross, H.H.

1980-01-11

A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

New constraints on Northern Hemisphere growing season net flux

NASA Astrophysics Data System (ADS)

Yang, Z.; Washenfelder, R. A.; Keppel-Aleks, G.; Krakauer, N. Y.; Randerson, J. T.; Tans, P. P.; Sweeney, C.; Wennberg, P. O.

2007-06-01

Observations of the column-averaged dry molar mixing ratio of CO2 above both Park Falls, Wisconsin and Kitt Peak, Arizona, together with partial columns derived from aircraft profiles over Eurasia and North America are used to estimate the seasonal integral of net ecosystem exchange (NEE) between the atmosphere and the terrestrial biosphere in the Northern Hemisphere. We find that NEE is ~25% larger than predicted by the Carnegie Ames Stanford Approach (CASA) model. We show that the estimates of NEE may have been biased low by too weak vertical mixing in the transport models used to infer seasonal changes in Northern Hemisphere CO2 mass from the surface measurements of CO2 mixing ratio.

Continuous-flow free acid monitoring method and system

DOEpatents

Strain, James E.; Ross, Harley H.

1981-01-01

A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

External root resorption of the second molar associated with third molar impaction: comparison of panoramic radiography and cone beam computed tomography.

PubMed

Oenning, Anne Caroline Costa; Neves, Frederico Sampaio; Alencar, Phillipe Nogueira Barbosa; Prado, Rodrigo Freire; Groppo, Francisco Carlos; Haiter-Neto, Francisco

2014-08-01

The aim of the present study was to compare panoramic radiography and cone beam computed tomography (CBCT) for the assessment of external root resorption (ERR) of second molars associated with impacted third molars. In addition, the prevalence of ERR in second molars and the inclinations of the third molars more associated with ERR were investigated in both imaging methods. The sample consisted of 66 individuals with maxillary and mandibular impacted third molars (n = 188) seen on panoramic radiographs and CBCT images. The presence of ERR on the adjacent second molar was investigated, and the position of the third molar was determined using Winter's classification (vertical, horizontal, mesioangular, distoangular, and transverse). Statistical analysis was performed using the χ(2) test, Fisher exact test, and 2-proportion Z test (the significance level was set at 5%). A significantly greater number of cases of ERR (P < .0001) was diagnosed from CBCT images (n = 43, 22.88%) than panoramic radiographs (n = 10, 5.31%). The agreement between the panoramic radiographs and CBCT scans for diagnosing ERR was 4.3%. Mandibular third molars in mesioangular and horizontal inclinations were more likely to cause resorption of the adjacent teeth. CBCT should be indicated for the diagnosis of ERR in second molars when direct contact between the mandibular second and third molars has been observed on panoramic radiographs, especially in mesioangular or horizontal impactions. Furthermore, considering the propensity of these teeth to cause ERR in second molars, third molar prophylactic extraction could be suggested. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Banding versus bonding of first permanent molars: a multi-centre randomized controlled trial.

PubMed

Nazir, Mariyah; Walsh, Tanya; Mandall, Nicky A; Matthew, Susie; Fox, Dee

2011-06-01

To assess the effectiveness of banding versus bonding of first permanent molars during fixed appliance treatment; in terms of attachment failure, patient discomfort and post-treatment enamel demineralization. Multi-centre randomized clinical trial. One District General Hospital Orthodontic Department and two Specialist Orthodontic Practices. Orthodontic patients aged between 10 and 18 years old, randomly allocated to either receive molar bands (n=40) or molar bonds (n=40). Bands were cemented with a conventional glass ionomer cement and tubes were bonded with light-cured composite to all four first permanent molar teeth for each subject. Attachments were reviewed at each recall appointment to assess loosening or loss. The clinical end point of the trial was the day of appliance debond. Enamel demineralization at debond was assessed using the modified International Caries Assessment and Detection System (ICDAS). The first time failure rate for molar bonds was 18·4% and 2·6% for molar bands (P=0·0002). Survival analysis demonstrated molar bonds were more likely to fail compared with molar bands. First permanent molars with bonded tubes experienced more demineralization than those with cemented bands (P=0·027). There was no statistically significant difference in discomfort experienced by patients after banding or bonding first permanent molars (P>0·05). This study shows that as part of fixed appliance therapy, American Orthodontics photoetched first permanent molar bands cemented with 3M ESPE Ketac-Cem perform better than American Orthodontics low profile photo-etched and mesh-based first permanent molar tubes bonded with 3M Unitek Transbond XT in terms of failure behaviour and molar enamel demineralization.

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

PubMed

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

2014-09-01

We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 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.

Endodontic treatment of an unusual connation of permanent mandibular molars: a case report.

PubMed

Liu, Shengbo; Fan, Bing; Peng, Bin; Fan, Mingwen; Bian, Zhuan

2006-10-01

A 27-year-old patient with an anomalous mandibular molar was referred for endodontic therapy. Clinical and radiographic examination revealed the connation of a second mandibular molar with a third molar. Challenging endodontic therapy was performed in the unusual connated molars. A 2-year recall showed good treatment result.

Third molar development: measurements versus scores as age predictor.

PubMed

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

2011-10-01

Human third molar development is widely used to predict chronological age of sub adult individuals with unknown or doubted age. For these predictions, classically, the radiologically observed third molar growth and maturation is registered using a staging and related scoring technique. Measures of lengths and widths of the developing wisdom tooth and its adjacent second molar can be considered as an alternative registration. The aim of this study was to verify relations between mandibular third molar developmental stages or measurements of mandibular second molar and third molars and age. Age related performance of stages and measurements were compared to assess if measurements added information to age predictions from third molar formation stage. The sample was 340 orthopantomograms (170 females, 170 males) of individuals homogenously distributed in age between 7 and 24 years. Mandibular lower right, third and second molars, were staged following Gleiser and Hunt, length and width measurements were registered, and various ratios of these measurements were calculated. Univariable regression models with age as response and third molar stage, measurements and ratios of second and third molars as predictors, were considered. Multivariable regression models assessed if measurements or ratios added information to age prediction from third molar stage. Coefficients of determination (R(2)) and root mean squared errors (RMSE) obtained from all regression models were compared. The univariable regression model using stages as predictor yielded most accurate age predictions (males: R(2) 0.85, RMSE between 0.85 and 1.22 year; females: R(2) 0.77, RMSE between 1.19 and 2.11 year) compared to all models including measurements and ratios. The multivariable regression models indicated that measurements and ratios added no clinical relevant information to the age prediction from third molar stage. Ratios and measurements of second and third molars are less accurate age predictors than stages of developing third molars. Copyright © 2011 Elsevier Ltd. All rights reserved.

Monitoring for periodontal inflammatory disease in the third molar region.

PubMed

Golden, Brent A; Baldwin, Carrie; Sherwood, Colin; Abdelbaky, Omar; Phillips, Ceib; Offenbacher, Steven; White, Raymond P

2015-04-01

To assess changes at 2-year intervals in the periodontal status of the third molar region in participants enrolled with asymptomatic third molars and no clinical evidence of third molar region periodontal pathology. The included participants who presented with a healthy periodontal status (all probing depths [PDs], <4 mm) in the third molar region, defined as distal of second molars and around adjacent third molars, were from a larger longitudinal study of participants with asymptomatic third molars. Full-mouth periodontal PD data from 6 sites per tooth were obtained clinically at enrollment and at subsequent 2-year intervals. Data were aggregated to the patient level. Outcome variables were the presence or absence of periodontal pathology, defined as at least 1 PD of at least 4 mm in the third molar region. One hundred twenty-nine participants had a third molar region PD shallower than 4 mm at enrollment. Most participants were Caucasian (85%), women (60%), younger than 25 years (62%), educated beyond high school (84%), and with good oral health habits. At 6 years, excluding the 61 participants lost to follow-up, 47% participants had had third molars removed, 21% had developed at least 1 PD of at least 4 mm in the third molar region since enrollment, and 32% retained the periodontal status at enrollment (all PDs in third molar region, <4 mm). Demographic characteristics were not statistically different for participants followed for 6 years compared with those lost to follow-up. Although not all participants could be followed for 6 years after enrollment or chose to retain third molars, one third of participants maintained the third molar region periodontal status assessed at baseline for 6 years after enrollment; no clinical evidence of pathology developed over time. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

42 CFR 488.715 - Partial extended surveys.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 5 2013-10-01 2013-10-01 false Partial extended surveys. 488.715 Section 488.715... (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Home Health Agencies § 488.715 Partial extended surveys. A partial extended survey is conducted...

42 CFR 488.715 - Partial extended surveys.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 5 2014-10-01 2014-10-01 false Partial extended surveys. 488.715 Section 488.715... (CONTINUED) STANDARDS AND CERTIFICATION SURVEY, CERTIFICATION, AND ENFORCEMENT PROCEDURES Survey and Certification of Home Health Agencies § 488.715 Partial extended surveys. A partial extended survey is conducted...

Radiographic assessment of third molars development and it's relation to dental and chronological age in an Iranian population.

PubMed

Monirifard, Mohamad; Yaraghi, Navid; Vali, Ava; Vali, Asana; Vali, Amrita

2015-01-01

The aim of the present study was to estimate chronological age based on third molar development and to determine the association between dental age and third molar calcification stages. In this cross-sectional study, 505 digital panoramic radiographs of 223 males (44.2%) and 282 females (55.8%) between the age of 6 and 17 were selected from patients who were treated in Departments of Pediatrics and Orthodontics of Isfahan University of Medical Sciences between the years of 2009 and 2013. Correlation between chronological age and third molar development was analyzed with SPSS 21 using Spearman's Rank correlation coefficient, Chi-square test and multiple regression statistical tests (P < 0.05). All third molars demonstrated a highly significant correlation with dental age (P < 0.001). The teeth showing the highest relationship with dental age were mandibular left third molar in males and mandibular right third molar in females (r s = 0.072). When multiple regression was used to predict dental age based on molar calcification stage, the only significant correlation was between maxillary left third molar in males (P < 0.05). There was no statistically significant correlation for any of third molars in females. Relationship between chronological age and molars development stage was significant in all age subgroups and in both gender (P < 0.001). Strong correlation was observed between left third molars and dental age in males. Results showed that third molar calcification stage can be used as an age predictor and in general mandibular teeth seems to be more reliable for this purpose in both genders and in all ages.

External root resorption of the second molar associated with mesially and horizontally impacted mandibular third molar: evidence from cone beam computed tomography.

PubMed

Wang, Dongmiao; He, Xiaotong; Wang, Yanling; Li, Zhongwu; Zhu, Yumin; Sun, Chao; Ye, Jinhai; Jiang, Hongbing; Cheng, Jie

2017-05-01

The aim of the present study was to assess the incidence and risk factors of ERR in second molars with mesially and horizontally impacted mandibular third molars using cone beam computed tomography (CBCT) images from patients in a Chinese tertiary referral hospital. A total number of 216 patients with 362 mesially and horizontally impacted mandibular third molars who were treated at our institution from 2014 to 2015 was retrospectively included. The ERR in second molars was identified on CBCT multiplanar images. The associations between incidence of ERR and multiple clinical parameters were statistically analyzed by Chi-square test. Moreover, the risk factors for ERR in second molars were further assessed by multivariate regression analysis. The overall incidence of ERR in second molars was 20.17 % (73/362) as detected on CBCT images. The presence of ERR significantly associated with patients age and impaction depth of mandibular third molars. However, no significant relationship was found between ERR severity and impaction depth or ERR location. Multivariate regression analyses further revealed age over 35 years and impaction depth as important risk factors affecting the ERR incidence caused by mesial and horizontal impaction of mandibular third molar. ERR in second molar resulted from mesially and horizontally impacted mandibular third molar is not very rare and can be reliably identified via CBCT scan. Given the possibility of ERR associated with third molar impaction, the prophylactic removal of these impacted teeth could be considered especially for those patients with over 35 years and mesially and horizontally impacted teeth.

Effects of feeding crude glycerin on performance and ruminal kinetics of lactating Holstein cows fed corn silage- or cottonseed hull-based, low-fiber diets.

PubMed

Shin, J H; Wang, D; Kim, S C; Adesogan, A T; Staples, C R

2012-07-01

The objective was to determine whether crude glycerin could partially replace concentrate ingredients in corn silage- or cottonseed hull-based diets formulated to support minimal milk fat production without reducing milk production. Multiparous, lactating Holstein cows (n=24; 116 ± 13d in milk) were assigned to dietary treatments arranged in a 2 × 3 factorial design; namely, 2 dietary roughage sources (cottonseed hulls or corn silage) and 3 dietary concentrations of glycerin [0, 5, or 10% on a dry matter (DM) basis]. Four different cows received each dietary treatment in each of 3 periods such that each diet was evaluated using 12 cows. Crude glycerin, produced using soybean oil, contained 12% water, 5% oil, 6.8% sodium chloride, and 0.4% methanol. Glycerin partially replaced ground corn, corn gluten feed, and citrus pulp. Diets of minimum fiber concentrations were fed to lactating dairy cows and resulted in low concentrations of milk fat (averaging 3.12% for cows fed diets without glycerin). The effects of glycerin on cow performance and ruminal measurements were the same for both dietary roughage sources with the exception of feed efficiency. Replacing concentrate with crude glycerin at 5% of dietary DM increased DM intake without increasing milk yield. Concentration and yield of milk fat were reduced when glycerin was fed at 10% of dietary DM. This was accompanied by a 30% reduction in apparent total-tract digestion of dietary neutral detergent fiber. Crude glycerin affected the microbial population in the rumen as evidenced by increased molar proportions of propionic, butyric, and valeric acids and decreased molar proportions of acetic acid. Efficiency of N utilization was improved as evidenced by lower concentrations of blood urea nitrogen and ruminal ammonia-N. Cows fed cottonseed hull-based diets consumed 5.3 kg/d more DM but produced only 1.7 kg/d more milk, resulting in reduced efficiency. Increased production of ruminal microbial protein, molar proportion of propionic acid, and passage of ruminal fluid resulted from feeding the cottonseed hull- versus corn silage-based diets, although apparent digestibilities of DM and neutral detergent fiber were reduced. Replacing 5 and 10% of concentrate ingredients with crude glycerin improved efficiency of 4% fat-corrected milk production when corn silage-based diets were fed but decreased it when cottonseed hull-based diets were fed. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Spectrum of excess partial molar absorptivity. Part II: a near infrared spectroscopic study of aqueous Na-halides.

PubMed

Sebe, Fumie; Nishikawa, Keiko; Koga, Yoshikata

2012-04-07

Our earlier thermodynamic studies suggested that F(-) and Cl(-) form hydration shells with the hydration number 14 ± 2 and 2.3 ± 0.6, respectively, and leave the bulk H(2)O away from hydration shells unperturbed. Br(-) and I(-), on the other hand, form hydrogen bonds directly with the momentarily existing hydrogen bond network of H(2)O, and retard the degree of entropy-volume cross fluctuation inherent in liquid H(2)O. The effect of the latter is stronger for I(-) than Br(-). Here we seek additional information about this qualitative difference between Cl(-) and (Br(-) and I(-)) pair by near infrared (NIR) spectroscopy. We analyze the ν(2) + ν(3) band of H(2)O in the range 4600-5500 cm(-1) of aqueous solutions of NaCl, NaBr and NaI, by a new approach. From observed absorbance, we calculate excess molar absorptivity, ε(E), excess over the additive contributions of solute and solvent. ε(E) thus contains information about the effect of inter-molecular interactions in the ν(2) + ν(3) spectrum. The spectrum of ε(E) shows three bands; two negative ones at 5263 and 4873 cm(-1), and the positive band at 5123 cm(-1). We then define and calculate the excess partial molar absorptivity of each salt, ε(E)(salt). From the behaviour of ε(E)(salt) we suggest that the negative band at 5263 cm(-1) represents free H(2)O without much hydrogen bonding under the influence of local electric field of ions. Furthermore, from a sudden change in the x(salt) (mole fraction of salt) dependence of ε(E)(salt), we suggest that there is an ion-pairing in x(salt) > 0.032, 0.036, and 0.04 for NaCl, NaBr and NaI respectively. The positive band of ε(E) at 5123 cm(-1) is attributed to a modestly organized hydrogen bond network of H(2)O (or liquid-likeness), and the x(salt) dependence of ε indicated a qualitative difference in the effect of Cl(-) from those of Br(-) and I(-). Namely, the values of ε(E)(salt) stay constant for Cl(-) but those for Br(-) and I(-) decrease smoothly on increasing the salt mole fraction. The mole fraction dependence of ε(E)(salt) at the 4873 cm(-1) band, due to ice-likeness in H(2)O, shows a subtle difference between Cl(-) and (Br(-), I(-)) pair.

Solubility enhancement of simvastatin by arginine: thermodynamics, solute-solvent interactions, and spectral analysis.

PubMed

Meor Mohd Affandi, M M R; Tripathy, Minaketan; Shah, Syed Adnan Ali; Majeed, A B A

2016-01-01

We examined the solubility of simvastatin in water in 0.01 mol·dm(-3), 0.02 mol·dm(-3), 0.04 mol·dm(-3), 0.09 mol·dm(-3), 0.18 mol·dm(-3), 0.36 mol·dm(-3), and 0.73 mol·dm(-3) arginine (ARG) solutions. The investigated drug is termed the solute, whereas ARG the cosolute. Phase solubility studies illustrated a higher extent of solubility enhancement for simvastatin. The aforementioned system was subjected to conductometric and volumetric measurements at temperatures (T) of 298.15 K, 303.15 K, 308.15 K, and 313.15 K to illustrate the thermodynamics involved and related solute-solvent interactions. The conductance values were used to evaluate the limiting molar conductance and association constants. Thermodynamic parameters (ΔG (0), ΔH (0), ΔS (0), and E s) for the association process of the solute in the aqueous solutions of ARG were calculated. Limiting partial molar volumes and expansibilities were evaluated from the density values. These values are discussed in terms of the solute-solvent and solute-cosolute interactions. Further, these systems were analyzed using ultraviolet-visible analysis, Fourier-transform infrared spectroscopy, and (13)C, (1)H, and two-dimensional nuclear overhauser effect spectroscopy nuclear magnetic resonance to complement thermophysical explanation.

Synthesis, spectroscopic and antimicrobial studies of La(III), Ce(III), Sm(III) and Y(III) Metformin HCl chelates.

PubMed

Refat, Moamen S; Al-Azab, Fathi M; Al-Maydama, Hussein M A; Amin, Ragab R; Jamil, Yasmin M S; Kobeasy, Mohamed I

2015-05-05

Metal complexes of Metformin hydrochloride were prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes were discussed and synthesized to serve as potential insulin-mimetic. Some physical properties and analytical data of the four complexes were checked. The elemental analysis shows that La(III), Ce(III) Sm(III) and Y(III) formed complexes with Metformin in 1:3 (metal:MF) molar ratio. All the synthesized complexes are white and possess high melting points. These complexes are soluble in dimethylsulfoxide and dimethylformamide, partially soluble in hot methanol and insoluble in water and some other organic solvents. From the spectroscopic (infrared, UV-vis and florescence), effective magnetic moment and elemental analyses data, the formula structures are suggested. The results obtained suggested that Metformin reacted with metal ions as a bidentate ligand through its two imino groups. The molar conductance measurements proved that the Metformin complexes are slightly electrolytic in nature. The kinetic thermodynamic parameters such as: E(∗), ΔH(∗), ΔS(∗) and ΔG(∗) were estimated from the DTG curves. The antibacterial evaluations of the Metformin and their complexes were also performed against some gram positive, negative bacteria as well as fungi. Copyright © 2015 Elsevier B.V. All rights reserved.

Volume properties and refraction of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids lysine, threonine, and oxyproline (C60(C6H13N2O2)2, C60(C4H8NO3)2, and C60(C5H9NO2)2) at 25°C

NASA Astrophysics Data System (ADS)

Semenov, K. N.; Ivanova, N. M.; Charykov, N. A.; Keskinov, V. A.; Kalacheva, S. S.; Duryagina, N. N.; Garamova, P. V.; Kulenova, N. A.; Nabieva, A.

2017-02-01

Concentration dependences of the density of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids are studied by pycnometry. Concentration dependences of the average molar volumes and partial volumes of components (H2O and corresponding bisadducts) are calculated for C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems at 25°C. Concentration dependences of the indices of refraction of C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems are determined at 25°C. The concentration dependences of specific refraction and molar refraction of bisadducts and aqueous solutions of them are calculated.

A case of squamous cell carcinoma presenting as localized severe periodontitis in the maxillary gingiva.

PubMed

Kim, Ok-Su; Uhm, So-Won; Kim, Sang-Chul; Lee, Bo-Ah; Kim, Ok-Joon; Kim, Young-Joon; Chung, Hyun-Ju

2012-06-01

Squamous cell carcinoma (SCC) is the most common malignant neoplasm of the oral cavity. The clinical features of gingival SCC include alveolar bone loss and erythematous lesion. Therefore, gingival SCC sometimes presents as advanced periodontitis. This case report describes a patient diagnosed with gingival SCC after the extraction of molars presenting as being affected by localized severe periodontitis. The patient was a 61-year-old man whose chief complaint was pain in the left maxillary area. Clinical and radiographic examinations revealed common findings of a periodontal abscess on the left maxillary first and second molars. These teeth were extracted based on a diagnosis of a periodontal abscess. Three months later, a rapidly growing exophytic soft tissue mass was observed, and a biopsy of the mass was performed. According to the biopsy, the final diagnosis was a well-differentiated SCC. The patient was treated with a partial maxillectomy of the left maxilla and split-thickness skin graft. Two years after treatment, the patient remained free of recurrence. Gingival SCC is quite different from other forms of SCC, mimicking localized periodontal disease. Therefore, it can be misdiagnosed as localized periodontal disease and is generally discovered after extracting teeth. Therefore, clinicians must diagnose these lesions carefully and follow up with the patient after tooth extraction.

Periodontal Regenerative Therapy in Patient with Chronic Periodontitis and Type 2 Diabetes Mellitus: A Case Report.

PubMed

Seshima, Fumi; Nishina, Makiko; Namba, Takashi; Saito, Atsushi

2016-01-01

We report a case of generalized chronic periodontitis and type 2 diabetes mellitus requiring periodontal treatment including regenerative therapy. The patient was a 66-year-old man who presented with the chief complaint of gingival inflammation and mobile teeth in the molar region. He had been being treated for type 2 diabetes mellitus since 1999. His glycated hemoglobin (HbA1c) level was 7.8%. An initial examination revealed sites with a probing depth of ≥7 mm in the molar region, and radiography revealed angular bone defects in this area. Based on a clinical diagnosis of generalized chronic periodontitis, the patient underwent initial periodontal therapy. An improvement was observed in periodontal conditions on reevaluation, and his HbA1c level showed a reduction to 6.9%. Periodontal regenerative therapy with enamel matrix derivative was then performed on #16, 26, and 27. Following another reevaluation, a removable partial denture was fabricated for #47 and the patient placed on supportive periodontal therapy (SPT). To date, periodontal conditions have remained stable and the patient's HbA1c level has increased to 7.5% during SPT. The results show the importance of collaboration between dentist and physician in managing periodontal and diabetic conditions in such patients.

Solubility enhancement of simvastatin by arginine: thermodynamics, solute–solvent interactions, and spectral analysis

PubMed Central

Meor Mohd Affandi, MMR; Tripathy, Minaketan; Shah, Syed Adnan Ali; Majeed, ABA

2016-01-01

We examined the solubility of simvastatin in water in 0.01 mol·dm−3, 0.02 mol·dm−3, 0.04 mol·dm−3, 0.09 mol·dm−3, 0.18 mol·dm−3, 0.36 mol·dm−3, and 0.73 mol·dm−3 arginine (ARG) solutions. The investigated drug is termed the solute, whereas ARG the cosolute. Phase solubility studies illustrated a higher extent of solubility enhancement for simvastatin. The aforementioned system was subjected to conductometric and volumetric measurements at temperatures (T) of 298.15 K, 303.15 K, 308.15 K, and 313.15 K to illustrate the thermodynamics involved and related solute–solvent interactions. The conductance values were used to evaluate the limiting molar conductance and association constants. Thermodynamic parameters (ΔG0, ΔH0, ΔS0, and Es) for the association process of the solute in the aqueous solutions of ARG were calculated. Limiting partial molar volumes and expansibilities were evaluated from the density values. These values are discussed in terms of the solute–solvent and solute–cosolute interactions. Further, these systems were analyzed using ultraviolet–visible analysis, Fourier-transform infrared spectroscopy, and 13C, 1H, and two-dimensional nuclear overhauser effect spectroscopy nuclear magnetic resonance to complement thermophysical explanation. PMID:27041998

Efficacy of resin infiltration of proximal caries in primary molars: 1-year follow-up of a split-mouth randomized controlled clinical trial.

PubMed

Ammari, Michelle Mikhael; Jorge, R C; Souza, I P R; Soviero, V M

2018-04-01

The main purpose of this split month, randomized, controlled clinical trial was evaluate the efficacy of caries infiltration in controlling the progression of non-cavitated proximal lesions in primary molars. Anxiety and time required for the caries infiltration was also evaluated. Fifty healthy children, 5 to 9 years, presenting two primary molars with proximal caries lesions (1/2 of the enamel or outer 1/3 of dentin), were included. Lesions were randomly allocated to the test group (fluoridated toothpaste + flossing + infiltration) or to the control group (fluoridated toothpaste + flossing). Caries risk was based on the Cariogram model. The main outcome after 1-year radiographic follow up was assessed by an independent blinded examiner A facial image scale (FIS) was applied to assess dental anxiety and time required to perform the infiltration was recorded. Of the sample, 92.9% corresponded to high or medium caries risk. In 42 patients (1-year follow up), caries progression was observed in 11.9% (5/42) of the test lesions compared with 33.3% (14/42) of the control lesions (p < 0.05). Five control and three test lesions progressed to the middle 1/3 of dentin and were restored. No side effects were observed. Anxiety was both low before and after the treatment, and mean time required for the infiltration was 11.29 min (± 1.16 min). Caries infiltration of proximal caries lesions in primary molars is significantly more efficacious than standard therapy alone (fluoride toothpaste + flossing). Caries infiltration is an applicable and well-accepted method be used in children, representing a promising micro-invasive approach.

Neurosensoric disturbances after surgical removal of the mandibular third molar based on either panoramic imaging or cone beam CT scanning: A randomized controlled trial (RCT)

PubMed Central

Vaeth, Michael; Wenzel, Ann

2016-01-01

Objective: Pre-surgical CBCT has been suggested before removal of the mandibular third molar. Currently, the standard-of-care is two-dimensional (2D) panoramic imaging. The aim of this randomized controlled trial was to analyse possible differences in neurosensoric disturbances of the inferior alveolar nerve between patients undergoing either panoramic imaging or CBCT before surgical removal of the mandibular third molar. Furthermore, the aim was to perform a sensitivity analysis to assess the statistical significance of different assumptions related to sample size calculations. Methods: 230 patients were randomized to a scan group and a non-scan group. All patients were referred from practicing dentists in the Copenhagen area. Inclusion criteria were overlap of the root complex and the mandibular canal on a 2D radiographic image. Central allocation of the randomization code and double blind settings were established. The surgical removal was performed in a specialized surgical practice geographically and personally separated from the study practice. Registration of neurosensoric anomalies was performed with a Semmes–Weinstein test and a visual analogue scale questionnaire pre- and post-surgically. Results: In the scan group (n = 114), 21 episodes of neurosensoric disturbances were registered and in the non-scan group (n = 116), 13 episodes of neurosensoric disturbances were registered. There was no statistically significant difference between the two groups (p = 0.14). Performing a sensitivity analysis confirmed that CBCT was not superior to panoramic imaging in avoiding neurosensoric disturbances. Conclusions: The use of CBCT before removal of the mandibular third molar does not seem to reduce the number of neurosensoric disturbances. PMID:26648386

Neurosensoric disturbances after surgical removal of the mandibular third molar based on either panoramic imaging or cone beam CT scanning: A randomized controlled trial (RCT).

PubMed

Petersen, Lars B; Vaeth, Michael; Wenzel, Ann

2016-01-01

Pre-surgical CBCT has been suggested before removal of the mandibular third molar. Currently, the standard-of-care is two-dimensional (2D) panoramic imaging. The aim of this randomized controlled trial was to analyse possible differences in neurosensoric disturbances of the inferior alveolar nerve between patients undergoing either panoramic imaging or CBCT before surgical removal of the mandibular third molar. Furthermore, the aim was to perform a sensitivity analysis to assess the statistical significance of different assumptions related to sample size calculations. 230 patients were randomized to a scan group and a non-scan group. All patients were referred from practicing dentists in the Copenhagen area. Inclusion criteria were overlap of the root complex and the mandibular canal on a 2D radiographic image. Central allocation of the randomization code and double blind settings were established. The surgical removal was performed in a specialized surgical practice geographically and personally separated from the study practice. Registration of neurosensoric anomalies was performed with a Semmes-Weinstein test and a visual analogue scale questionnaire pre- and post-surgically. In the scan group (n = 114), 21 episodes of neurosensoric disturbances were registered and in the non-scan group (n = 116), 13 episodes of neurosensoric disturbances were registered. There was no statistically significant difference between the two groups (p = 0.14). Performing a sensitivity analysis confirmed that CBCT was not superior to panoramic imaging in avoiding neurosensoric disturbances. The use of CBCT before removal of the mandibular third molar does not seem to reduce the number of neurosensoric disturbances.

Taxonomic differences in deciduous upper second molar crown outlines of Homo sapiens, Homo neanderthalensis and Homo erectus.

PubMed

Bailey, Shara E; Benazzi, Stefano; Souday, Caroline; Astorino, Claudia; Paul, Kathleen; Hublin, Jean-Jacques

2014-07-01

A significant number of Middle to Late Pleistocene sites contain primarily (and sometimes only) deciduous teeth (e.g., Grotta del Cavallo, Mezmaiskaya, Blombos). Not surprisingly, there has been a recent renewed interest in deciduous dental variation, especially in the context of distinguishing Homo neanderthalensis and Homo sapiens. Most studies of the deciduous dentition of fossil hominins have focused on standard metrical variation but morphological (non-metric and morphometric) variation also promises to shed light on long standing taxonomic questions. This study examines the taxonomic significance of the crown outline of the deciduous upper second molar through principal components analysis and linear discriminant analysis. We examine whether or not the crown shape of the upper deciduous second molar separates H. neanderthalensis from H. sapiens and explore whether it can be used to correctly assign individuals to taxa. It builds on previous studies by focusing on crown rather than cervical outline and by including a large sample of geographically diverse recent human populations. Our samples include 17 H. neanderthalensis, five early H. sapiens, and 12 Upper Paleolithic H. sapiens. In addition, we include two Homo erectus specimens in order to evaluate the polarity of crown shape differences observed between H. neanderthalensis and H. sapiens. Our results show that crown outline shape discriminates H. sapiens and H. neanderthalensis quite well, but does not do well at distinguishing H. erectus from H. sapiens. We conclude that the crown outline shape observed in H. sapiens is a primitive retention and that the skewed shape observed in H. neanderthalensis is a derived condition. Finally, we explore the phylogenetic implications of the results for the H. erectus molars. Copyright © 2014 Elsevier Ltd. All rights reserved.

Size of the lower third molar space in relation to age in Serbian population.

PubMed

Zelić, Ksenija; Nedeljković, Nenad

2013-10-01

It is considered that the shortage of space is the major cause of the third molar impaction. The aim of this study was to establish the frequency of insufficient lower third molar eruption space in Serbian population, to question the differences in this frequency in the subjects of different age, to determine the influence of the lower third molar space (retromolar space) size on third molar eruption, and to investigate a possible correlation between the size of gonial angle and the space/third molar width ratio. Digital orthopantomograms were taken from 93 patients divided into two groups: early adult (16-18 years of age) and adult (18-26) patients. Retromolar space, mesiodistal third molar crown width, gonial angle and eruption levels were measured. The space/third molar width in early adult subjects was smaller (p < 0.0001) and insufficient space was significantly more frequent (p = 0.0003) than in adult patients. Considerably more third molars erupted in case of enough space in both age groups (p < 0.0001). There was no difference between the means of gonial angle size in relations to the available space. The retromolar space/third molar width ratio is more favorable in adult subjects. Gonial angle is not in correlation with the retromolar space/third molar width ratio.

Clinical significance of computed tomography assessment for third molar surgery

PubMed Central

Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

2014-01-01

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

Comparative evaluation of molar distalization therapy with erupted second molar: Segmented versus Quad Pendulum appliance.

PubMed

Caprioglio, Alberto; Cozzani, Mauro; Fontana, Mattia

2014-01-01

There are controversial opinions about the effect of erupted second molars on distalization of the first molars. Most of the distalizing devices are anchored on the first molars, without including second molars; so, differences between sequentially distalize maxillary molars (second molar followed by the first molar) or distalize second and first molars together are not clear. The aim of the study was to compare sequential versus simultaneous molar distalization therapy with erupted second molar using two different modified Pendulum appliances followed by fixed appliances. The treatment sample consisted of 35 class II malocclusion subjects, divided in two groups: group 1 consisted of 24 patients (13 males and 11 females) with a mean pre-treatment age of 12.9 years, treated with the Segmented Pendulum (SP) and fixed appliances; group 2 consisted of 11 patients (6 males and 5 females) with a mean pre-treatment age of 13.2 years, treated with the Quad Pendulum (QP) and fixed appliances. Lateral cephalograms were obtained before treatment (T1), at the end of distalization (T2), and at the end of orthodontic fixed appliance therapy (T3). A Student t test was used to identify significant between-group differences between T1 to T2, T2 to T3, and T1 to T3. QP and SP were equally effective in distalizing maxillary molars (3.5 and 4 mm, respectively) between T1 and T2; however, the maxillary first molar showed less distal tipping (4.6° vs. 9.6°) and more extrusion (1.1 vs. 0.2 mm) in the QP group than in the SP group, as well as the vertical facial dimension, which increased more in the QP group (1.2°) than in the SP group (0.7°). At T3, the QP group maintained greater increase in lower anterior facial height and molar extrusion and decrease in overbite than the SP group. Quad Pendulum seems to have greater increase in vertical dimension and molar extrusion than the Segmented Pendulum.

Development of Argon Isotope Reference Standards for the U.S. Geological Survey

PubMed Central

Miiller, Archie P.

2006-01-01

The comparison of physical ages of geological materials measured by laboratories engaged in geochronological studies has been limited by the accuracy of mineral standards or monitors for which reported ages have differed by as much as 2 %. In order to address this problem, the U.S. Geological Survey is planning to calibrate the conventional 40Ar/40K age of a new preparation of an international hornblende standard labeled MMhb-2. The 40K concentration in MMhb-2 has already been determined by the Analytical Chemistry Division at NIST with an uncertainty of 0.2 %. The 40Ar concentration will be measured by the USGS using the argon isotope reference standards that were recently developed by NIST and are described in this paper. The isotope standards were constructed in the form of pipette/reservoir systems and calibrated by gas expansion techniques to deliver small high-precision aliquots of high-purity argon. Two of the pipette systems will deliver aliquots of 38Ar having initial molar quantities of 1.567 × 10−10 moles and 2.313 × 10−10 moles with expanded (k = 2) uncertainties of 0.058 % and 0.054 %, respectively. Three other pipette systems will deliver aliquots (nominally 4 × 10−10 moles) of 40Ar:36Ar artificial mixtures with similar accuracy and with molar ratios of 0.9974 ± 0.06 %, 29.69 ± 0.06 %, and 285.7 ± 0.08 % (k = 2). These isotope reference standards will enable the USGS to measure the 40Ar concentration in MMhb-2 with an expanded uncertainty of ≈ 0.1 %. In the process of these measurements, the USGS will re-determine the isotopic composition of atmospheric Ar and calculate a new value for its atomic weight. Upon completion of the USGS calibrations, the MMhb-2 mineral standard will be certified by NIST for its K and Ar concentrations and distributed as a Standard Reference Material (SRM). The new SRM and the NIST-calibrated transportable pipette systems have the potential for dramatically improving the accuracy of interlaboratory calibrations and thereby the measured ages of geological materials, by as much as a factor of ten. PMID:27274937

Effect of Endocrown Pulp Chamber Extension Depth on Molar Fracture Resistance.

PubMed

Hayes, A; Duvall, N; Wajdowicz, M; Roberts, H

The purpose of this study was to evaluate the effect of endocrown pulp chamber extension on mandibular molar fracture resistance. A total of 36 recently extracted mandibular third molars of approximate equal size were sectioned at the facial lingual height of contour followed by endodontic access into the pulp chamber. The specimens were then randomly divided into three groups (n=12) and pulpal and root canal contents removed. Pulp chamber floors were established at 2, 3, and 4 mm from the occlusal table using a three-step etch-and-rinse adhesive and a flowable resin composite. The prepared specimens were then embedded in auto-polymerizing denture base resin with surface area available for adhesive bonding determined using a digital recording microscope. Specimens were restored using a standardized template with a chairside computer-aided design/computer-aided manufacturing unit with the endocrown milled from a lithium disilicate glass-ceramic material. Restoration parameters of occlusal table anatomy and thickness were standardized with the only parameter difference being the pulp chamber extension depth. The endocrown restorations were luted with a self-adhesive resin luting agent and tested to failure after 24 hours on a universal testing machine, with force applied to the facial cusps at a 45° angle to the long axis of the tooth. The failure load was converted into stress for each specimen using the available surface area for bonding. Mean failure load and stress among the three groups was first subjected to the Shapiro-Wilk and Bartlett tests and then analyzed with an analysis of variance with the Tukey post hoc test at a 95% confidence level (p=0.05). The 2- and 4-mm chamber extension groups demonstrated the highest fracture resistance stress, with the 3-mm group similar to the 2-mm group. The 3- and 4-mm chamber extension group specimens demonstrated nearly universal catastrophic tooth fracture, whereas half the 2-mm chamber extension group displayed nonrestorable root fractures. Under the conditions of this study, mandibular molars restored with the endocrown technique with 2- and 4-mm pulp chamber extensions displayed greater tooth fracture resistance force as well as stress. All groups demonstrated a high number of catastrophic fractures, but these results may not be clinically significant because the fracture force results are higher than normal reported values of masticatory function.