Molar Formation Research Articles

Thermodynamic properties of some isomeric 5-(nitrophenyl)-furyl-2 derivatives

BackgroundThe aim of the current work was to determine thermodynamical properties of 5-(nitrophenyl)-2-furaldehyde oximes and 3-[5-(nitrolphenyl)-2-furyl]acrylic acids.ResultsThe temperature dependences of saturated vapor pressures of 5-(nitrophenyl)-2-furaldehyde oximes and 3-[5-(nitrolphenyl)-2-furyl]acrylic acids were determined by the Knudsen effusion method. The results are presented by the Clapeyron–Clausius equation in linear form, and via this form, the standard enthalpies of sublimation 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 from the corresponding standard molar combustion enthalpy, obtained using combustion bomb calorimetry. The non-nearest neighbour interactions (strain) in molecule were defined. The ideal-gas enthalpies of investigated compounds formation and the data available from the literature were used for calculation of group-additivity parameters and the correction terms useful in the application of the Benson correlation.ConclusionDetermining the thermodynamic properties for these compounds will contribute to solving practical problems pertaining to optimization processes of their synthesis, purification and application. It will also provide a more thorough insight regarding the theoretical knowledge of their nature and are necessary for the application of the Benson group-contribution correlation for calculation of Delta {}_{f}H_{{m(298.15{text{K}})}}^{o} (g)calc.

Implications of Oxygen–Sulfur Exchange on Structural, Electronic Properties, and Stability of Alkali‐Metal Hexatitanates

The structural and electronic properties and thermal stability of a new series of sulfur‐containing compounds (A2Ti6S13 [A = Li+, Na+, or K+]) are studied using density functional theory (DFT). The calculated equilibrium lattice parameters are larger compared to their oxide counterparts, Li2Ti6O13, Na2Ti6O13, and K2Ti6O13. These new compounds are thermodynamically stable with standard molar formation enthalpies of −8743, −8389, and −8386 kJ mol−1, and a cell voltage per A+ insertion/desertion process of roughly 2 V, which is comparable with the oxygen‐based systems. The electronic band structures of these systems indicate a semiconductor‐to‐metallic transition, where the metallic character is more accentuated for K2Ti6S13 and Li2Ti6S13.

The Oligocene mollusc types of Gaetano Rovereto from Santa Giustina and Sassello (NW Italy)

The present paper examines the type specimens of the bivalve and gastropod taxa described by Gaetano Rovereto in the years 1897-1914 coming from the Oligocene rocks of Santa Giustina and Sassello areas (Molare Formation, Tertiary Piedmont Basin, Central Liguria, NW Italy). These taxa are part of the Collezione BTP (BTP Collection) housed at the Dipartimento di Scienze della Terra, dell'Ambiente e della Vita DISTAV of the Universita di Genova. The collecting sites reported in the Rovereto's papers and indicated on labels have been reinvestigated in the field. 22 taxa (6 gastropods and 16 bivalves) are revised and re-documented; 6 have been recognized as younger synonyms of other species, the others are valid taxa. The majority of this fauna is restricted to the Oligocene time and to the Tertiary Piedmont Basin.

A Comparison of Later Stage Dental Maturation in a Small Group of Children from Chernobyl and British Children

The aim of this study was to investigate the dental radiographic development of a small group of children born in Chernobyl, Ukraine, around the time of the nuclear disaster with an age matched group of British children. The design was a cross sectional non random retrospective study consisting of five boys and five girls from Chernobyl (age range 10.03 to 12.37) and 20 age and sex matched British children of white Caucasian origin. Developing permanent mandibular teeth were assessed from rotational tomograms using criteria described by Demirjian, Goldstein and Tanner (1973). Third molar formation was also assessed. Dental age was calculated and compared to real age using a t-test. The difference in dental age (DA) and real age (RA) was not significant when the two groups were compared. Dental age in both groups of children was advanced compared to the standards. These results suggest that the Chernobyl disaster has not affected root formation of late forming permanent teeth of these children.

Thermodynamic and thermal properties of the C60-l-Arg derivative

The paper presents experimental and DFT simulated data on temperature dependence of heat capacity for C60-l-arginine derivative. Smoothed Cp,m∘Tvalues in the temperature range from T → 0 K to 320 K are presented along with the values of standard thermodynamic functions: Sm°, [Hm∘T-Hm∘0] and [Φm∘T-Φm∘0]. In addition, the molar third law entropy and the molar formation entropy of the C60-l-arginine derivative in crystalline state at T = 298.15 K are calculated. The data on complex thermal analysis reveal that the C60-l-arginine derivative is stable up to 340 K. Further increasing of temperature leads to destruction of l-arginine groups and oxidation of fullerene core.

Lithium Hexastannate: A Potential Material for Energy Storage

The prediction of a new lithium compound, Li2Sn6O13, is made from a combined first‐principles and classical force‐field approach. The electronic, structural, and mechanical properties of monoclinic Li2SnO3, Li2Ti6O13, and Li2Sn6O13 are explored. The calculated results for the equilibrium lattice parameters are in agreement with the available experimental data. The thermodynamic stabilities of Li2Ti6O13 and Li2Sn6O13 are evaluated. Both compounds are demonstrated to be thermodynamically stable with standard molar formation enthalpies of −5553 and −6740 kJ mol−1, respectively. Reaction energies for delithiation of 6.41 and 6.90 eV atom−1 are also determined for Li2Sn6O13 and Li2Ti6O13, respectively. The predicted voltage of Li insertion/extraction process per Li+/Li is 1.6 V for Li2Sn6O13, comparable to its isostructural counterpart Li2Ti6O13. Electronic band structure calculations indicate the insulating character of Li2SnO3 with an indirect band gap of 4.4 eV, whereas both Li2Ti6O13 and Li2Sn6O13 appear to be semiconductor compounds with band gaps of 3.1 and 3.0 eV, respectivley. The energy barriers for Li+ migration amount to ≈0.5 eV for both materials. Elastic stiffness coefficients and bulk, shear and Young's moduli were also calculated. The Li2Sn6O13 derivative is mechanically stable and can be predicted to be a brittle compound that is more resistant to volume change than Li2Ti6O13. If the Li2Sn6O13 compound could experimentally be prepared by using ion exchange, it could potentially be an efficient material for anodes in lithium‐ion batteries.

Upstream Enhancer Elements of Shh Regulate Oral and Dental Patterning

Sonic hedgehog (Shh) is important in pattern formation during development. Shh transcription is modulated by a long-range regulatory mechanism containing a number of enhancers, which are spread over nearly 850 kb in the mouse genome. Shh enhancers in the nervous system have been found between intron and 430 kb upstream of Shh. Enhancers in the oral cavity, pharynx, lung, gut, and limbs have been discovered between 610 kb and 850 kb upstream of Shh. However, the intergenic region ranging from 430 to 610 kb upstream of Shh remains to be elucidated. In the present study, we found a novel long-range enhancer located 558 kb upstream of Shh. The enhancer showed in vivo activity in oral cavity and whiskers. A targeted deletion from the novel enhancer to mammal reptile conserved sequence 1 (MRCS1), which is a known enhancer of Shh in oral cavity, resulted in supernumerary molar formation, confirming the essential role of this intergenic region for Shh transcription in teeth. Furthermore, we clarified the binding of Lef1/Tcfs to the new enhancer and MRCS1, suggesting that Wnt/β-catenin signaling regulates Shh signaling in the oral cavity via these enhancers.

The WITS Atlas: A Black Southern African dental atlas for permanent tooth formation and emergence.

To develop a population-specific atlas of permanent tooth emergence and formation for age estimation of Black Southern Africans. Using data from a cross-sectional study of 642 school children aged 5-20 years, panoramic radiographs taken during routine dental examination in a mobile treatment van were analyzed using the Demirjian method of eight (A-H) tooth formation stages. Tables of the stages of tooth development for each tooth, including the third molars, were generated separately for age cohorts and by sex. The most frequently occurring (modal) stage of tooth formation was considered the signature developmental stage for the age. The relationship of the third molar occlusal surfaces with occlusal tables on the radiographs were checked and compared with the findings recorded during intra oral examination. Comparison with the London atlas shows that at age 9.5 years, the canine and premolar emergence are at least one year ahead and the third molar formation completes four years earlier in the WITS Atlas. Similarities in advancement in tooth formation and emergence across sub-Saharan Africa suggest that the WITS Atlas can be used for those populations as well.

QSPR Prediction of Retention Times of Methylxanthines and Cotinine by Bioplastic Evolution

High-performance liquid-chromatographic retention times of methylxanthines and cotinine in human plasma and urine are modelled by structure–property relationships. Bioplastic evolution is an evolutionary perspective conjugating the effect of acquired characters, and relations that emerge among the principles of evolutionary indeterminacy, morphological determination and natural selection. It is applied to design co-ordination index, which is used to characterize retentions of methylxanthines, etc. Parameters used to calculate co-ordination index are formation enthalpy, molecular weight and surface area. Morphological and co-ordination indices provide strong correlations. Effect of different types of features like thermodynamic, fractal, etc., are analyzed. The molar formation enthalpy, fractal dimensions, etc. distinguished methylxanthines and cotinine in linear fits. Different behaviour depends on number of C+N+O atoms.

Third molar development in South Africans and the probability of being 18 years of age

Dental development is frequently used to estimate age in cases involving skeletal remains, mass disasters, children with no identification documents and asylum seekers. Limited data are available for South Africans around the critical age of 18 years. After age 14, the only available immature tooth to estimate age with is the third molar. European age estimation models are often followed and age of individuals estimated by using unrepresentative data. The aim of this study was to estimate whether a person is legally an adult, i.e., what is the probability of being younger/older than 18 years, based on third molar development. Retrospective panoramic radiographs of 1268 individuals aged 15–25 years were studied from the School of Dentistry, University of Pretoria, South Africa. Proportionate samples of males and females (633 and 635 respectively) aged 1–25 years of European and African ancestry (n = 705 and 563) were used. The developmental stage of the left upper and lower third molars for each individual was determined and scored according to the criteria developed by Solari et al. (2002). The probability of being at least 18 years of age at a given stage was determined for each population and sex, including a 95% confidence interval. The data demonstrated earlier maturation of African males and females of between 6 and 14 months compared to individuals of European origin in the last stage (stage H). Differences between males and females were noted with earlier maturation in males. The additional stages F1 and G1 improved the evaluation of third molar formation. This dental data, along with other skeletal data, will be used to develop a multifactorial model for age estimation in living South Africans.

Tooth Morphogenesis and FGF4 Expression During Development of Molar Tooth in Three Muroid Rodents: Calomyscus elburzensis (Calomyscidae), Mesocricetus auratus (Cricetidae) and Mus musculus (Muridae).

To date, no studies have examined the tooth formation during developmental stages of brush-tailed mice (Calomyscidae) and true hamsters (Cricetidae). Herein, we compared the timing of tooth morphogenesis and FGF4 expression pattern during development of the first lower molar in Goodwin's brush-tailed mouse, Calomyscus elburzensis with two other muroid rodents; the house mouse, Mus musculus (Muridae), model organism for tooth morphogenesis, and the golden hamster, Mesocricetus auratus which shares great similarities in cusp pattern with brush-tailed mice. All three species were bred in captivity and developing embryos were isolated at different embryonic days (E). Histological evaluation of lower molars was performed and spatiotemporal pattern of FGF4 expression was determined by immunohistochemistry. Results indicated that morphogenesis of the tooth cusps starts at the beginning of the cap stage of the first lower molar (E14 in house mouse, about E11.5 in golden hamster and E22 in Goodwin's brush-tailed mouse). During the cap to bell stage (E15 in house mouse, E12 in golden hamster and at about E24 in Goodwin's brush-tailed mouse), a decrease in the expression of FGF4 was observed in the mesenchyme, except for the cusp tips. According to our observations, the developmental process of the first lower molar formation in Goodwin's brush-tailed mouse began much later as compared with the other two species. Despite the differences in the temporal pattern of molar development between these three members of the same superfamily (Muroidea), the correlation in the expression of FGF4 with specific stages of tooth morphogenesis supported its regulatory function. Anat Rec, 300:2138-2149, 2017. © 2017 Wiley Periodicals, Inc.

Regulated and unregulated halogenated disinfection byproduct formation from chlorination of saline groundwater

Coastal utilities exploiting mildly saline groundwater (<150 mg/L chloride) may be challenged by disinfection byproduct (DBP) formation, a concern likely to increase with sea-level rise. Groundwater from North Carolina coastal aquifers is characterized by large variations in concentrations of halides (bromide up to 10,600 μg/L) and dissolved organic carbon (up to 5.7 mg-C/L). Formation of 33 regulated and unregulated halogenated DBPs, including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles, haloacetamides, and haloacetaldehydes, was measured after simulated chlorination of 24 coastal North Carolina groundwater samples under typical chlorination conditions. Results of chlorination simulation show that THM levels exceeded the Primary Maximum Contaminant Levels in half of the chlorinated samples. Addition of halides to a low salinity groundwater (110 mg/L chloride) indicated that elevated bromide triggered DBP formation, but chloride was not a critical factor for their formation. DBP speciation, but not overall molar formation, was strongly correlated with bromide variations in the groundwater. THMs and HAAs dominated the measured halogenated DBPs on a mass concentration basis. When measured concentrations were weighted by metrics of toxic potency, haloacetonitriles, and to a lesser degree, haloacetaldehydes and HAAs, were the predominant contributors to calculated DBP-associated toxicity. For some samples exhibiting elevated ammonia concentrations, the addition of chlorine to form chloramines in situ significantly reduced halogenated DBP concentrations and calculated toxicity. HAAs dominated the calculated toxicity of chloraminated waters. Reverse osmosis treatment of saline groundwater (chloride >250 mg/L) can reduce DBP formation by removing halides and organic precursors. However, we show that in a case where reverse osmosis permeate is blended with a separate raw groundwater, the residual bromide level in the permeate could still exceed that in the raw groundwater, and thereby induce DBP formation in the blend. DBP-associated calculated toxicity increased for certain blends in this system due to the DBPs resulting from the combination of the elevated bromide concentration in the permeate and the organic precursors from the raw coastal groundwater.

A radiographic study of permanent molar development in wild Virunga mountain gorillas of known chronological age from Rwanda.

While dental development is important to life history investigations, data from wild known-aged great apes are scarce. We report on the first radiographic examination of dental development in wild Virunga mountain gorillas, using known-age skeletal samples recovered in Rwanda. In 43 individuals (0.0-14.94 years), we collected radiographs of mandibular molars, and where possible, cone beam CT scans. Molar crown and root calcification status was assessed using two established staging systems, and age prediction equations generated using polynomial regression. Results were compared to available data from known-age captive and wild chimpanzees. Mountain gorillas generally fell within reported captive chimpanzee distributions or exceeded them, exhibiting older ages at equivalent radiographic stages of development. Differences reflect delayed initiation and/or an extended duration of second molar crown development, and extended first and second molar root development, in mountain gorillas compared to captive chimpanzees. However, differences in the duration of molar root development were less evident compared to wild chimpanzees. Despite sample limitations, our findings extend the known range of variation in radiographic estimates of molar formation timing in great apes, and provide a new age prediction technique based on wild specimens. However, mountain gorillas do not appear accelerated in radiographic assessment of molar formation compared to chimpanzees, as they are for other life history traits. Future studies should aim to resolve the influence of species differences, wild versus captive environments, and/or sampling phenomena on patterns observed here, and more generally, how they relate to variation in tooth size, eruption timing, and developmental life history.

Formation of 2,6-dichloro-1,4-benzoquinone from aromatic compounds after chlorination

Halobenzoquinones are a group of disinfection byproducts formed by chlorination of certain substances in water. However, to date, the identities of halobenzoquinone precursors remain unknown. In this study, the formation of 2,6-dichloro-1,4-benzoquinone (DCBQ), a typical halobenzoquinone, from 31 aromatic compounds was investigated after 60 min of chlorination. DCBQ was formed from 21 compounds at molar formation yields ranging from 0.0008% to 4.9%. Phenol and chlorinated phenols served as DCBQ precursors, as reported previously. Notably, DCBQ was also formed from para-substituted phenolic compounds. Compounds with alkyl and carboxyl groups as para-substituents led to relatively higher molar formation yields of DCBQ. Moreover, p-quinone-4-chloroimide, 2,6-dichloroquinone-4-chloroimide (2,6-DCQC), and para-substituted aromatic amines (e.g., aniline and N-methyl aniline) served as DCBQ precursors upon chlorination. It was deduced that DCBQ was formed from the para-substituted aromatic amines via 3,5-dichloroquinone-4-chloroimide, a structural isomer of 2,6-DCQC. These results suggested that DCBQ was formed by chlorination of natural organic matter containing para-substituted phenolic species and para-substituted aromatic amines, despite the absence of phenol in water.

Purification and thermochemical properties of dihydromyricetin

This work reports the purification of dihydromyricetin (abbreviation: DMY) by the recrystallization method, with a yield of secondary recrystallization of up to 77 %. The products were confirmed by element and spectral analysis. The results showed a sharp R-bond absorption peak located around the near-ultraviolet band, which is close to K-bond absorption, illustrating the occurrence of a large conjugation of carbonyl with adjacent phenol and hydroxyl. This was further confirmed by the infrared (IR) spectrum, i.e., the carbonyl stretching vibration peaks were red-shifted from 1700 to 1641 cm−1. The standard thermodynamic energy was determined to be ΔcUmθ[DMY(s), 298.15 K] = −(5437.44 ± 5.14) kJ mol−1 by an oxygen bomb calorimeter. Furthermore, the standard molar enthalpy of combustion was calculated to be ΔcHmθ[DMY(s), 298.15 K] = −(5434.96 ± 5.14) kJ mol−1, and the standard molar formation enthalpy of DMY was estimated to be ΔfHmθ[DMY(s), 298.15 K] = −(2182.67 ± 5.33) kJ mol−1.

Study of the Mechanical Properties of a Conglomerate

This paper is devoted to the study of a conglomerate rock formation (Molare Formation) outcropping in southern Piedmont that forms a natural arch of environmental interest. Awareness with respect to the stability of this structure emerged after some intense rains which caused small collapses at the arch foot. The need for a proper characterization of the material in its natural state and its deterioration following increased water saturation is needed. A multidisciplinary approach based on the integration of both in situ and laboratory geophysical tests for the assessment of the rock structure at different scales was performed. Geological surveys together with seismic tomography and GPR have been executed on site. Petrographical and compositional studies of the matrix, ultrasonic pulse velocity measurements, electrical resistivity determinations and standard UCS test on large specimens are under development in laboratory.

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

BackgroundThe 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.ResultsThe 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.ConclusionsDetermination 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

Continuous Neoproterozoic to Ordovician sedimentation at the East Gondwana margin — Implications from detrital zircons of the Ross Orogen in northern Victoria Land, Antarctica

The Ross–Delamerian orogenic belt was formed along the eastern side of the Australian–East Antarctic continent during west-directed subduction of the Palaeo-Pacific Ocean in the early Palaeozoic. Northern Victoria Land (NVL) in Antarctica was located at a central position of the Ross-Delamerian system. Its metamorphic basement is formed by three lithotectonic units formerly interpreted as terranes: the Wilson, Bowers and Robertson Bay terranes (from west to east). Dating of detrital zircons from 14 metasedimentary samples of these terranes combined with petrographical and whole-rock geochemical studies give new insights into the stratigraphic and tectonic evolution of NVL. All samples show very similar zircon age spectra with two main intervals, a Ross/Pan-African-age interval (470–700Ma) and a Grenville-age interval (900–1300Ma), as well as subordinate craton-related ages dispersed over the range of ca. 1600–3500Ma. The Ross/Pan-African-age zircon population tends to get more dominant from the Priestley Formation of the Wilson Terrane to the Molar Formation of the Bowers Terrane, and finally to the Robertson Bay Group, whereas the number of craton-related ages diminishes in this direction. A common East Antarctic source area is indicated for all analyzed samples. The Priestley Formation was deposited on the Palaeo-Pacific passive continental margin of East Gondwana in the late Neoproterozoic after Rodinia breakup. The sequence was subsequently metamorphosed and intruded by the Granite Harbour Intrusives during the Ross Orogeny. The Molar Formation of the Bowers Terrane is interpreted as a turbiditic sequence deposited in an accretionary setting on the active continental margin in the Late Cambrian during and after accretion of the Glasgow island arc allochthon. The thick, homogeneous sequence of the Robertson Bay Group resulted from continuous turbiditic sedimentation in an accretionary wedge in front of the Ross Orogen after docking and imbrication of the Glasgow island arc in the Early Ordovician.

Klf10 regulates odontoblast differentiation and mineralization via promoting expression of dentin matrix protein 1 and dentin sialophosphoprotein genes.

Klf10, a member of the Krüppel-like family of transcription factors, is critical for osteoblast differentiation, bone formation and mineralization. However, whether Klf10 is involved in odontoblastic differentiation and tooth development has not been determined. In this study, we investigate the expression patterns of Klf10 during murine tooth development in vivo and its role in odontoblastic differentiation in vitro. Klf10 protein was expressed in the enamel organ and the underlying mesenchyme, ameloblasts and odontoblasts at early and later stages of murine molar formation. Furthermore, the expression of Klf10, Dmp1, Dspp and Runx2 was significantly elevated during the process of mouse dental papilla mesenchymal differentiation and mineralization. The overexpression of Klf10 induced dental papilla mesenchymal cell differentiation and mineralization as detected by alkaline phosphatase staining and alizarin red S assay. Klf10 additionally up-regulated the expression of odontoblastic differentiation marker genes Dmp1, Dspp and Runx2 in mouse dental papilla mesenchymal cells. The molecular mechanism of Klf10 in controlling Dmp1 and Dspp expression is thus to activate their regulatory regions in a dosage-dependent manner. Our results suggest that Klf10 is involved in tooth development and promotes odontoblastic differentiation via the up-regulation of Dmp1 and Dspp transcription.

Enthalpy of formation of (In, Gd)-doped barium cerate

Solution enthalpies of barium cerate doped by gadolinium and indium and a mixture of BaCl2+0.7CeCl3+2GdCl3+0.1InCl3 have been measured in 1moldm−3 HCl with 0.1moldm−3 KI. For the first time the standard molar formation enthalpy of BaCe0.7Gd0.2In0.1O2.85 has been determined by solution calorimetry as follows: ΔfH° (298.15K)=−1615.84±9.01kJmol−1. The stabilization energy for above-mentioned compound has been calculated as well. It has been shown that barium cerate doped gadolinium and indium has higher stabilization energy than BaCe0.7Nd0.2In0.1O2.85 and BaCeO3. The reaction enthalpy with CO2 interaction has been calculated for BaCe0.7Gd0.2In0.1O2.85.