Molar Formation Research Articles

Coordination Reaction of Alanine with Neodymium(III) and Erbium(III) Nitrate. Thermochemical study

The solid-state coordination reaction: Nd(NO3)3·6H2O(s)+4Ala(s) → Nd(Ala)4(NO3)3·H2O(s)+5H2O(l) and Er(NO3)3·6H2O(s)+4Ala(s) → Er(Ala)4(NO3)3·H2O(s)+5H2O(l) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in 2 mol L–1 HCl solvent of these two solid-solid coordination reactions have been measured using a calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpies of [Nd(Ala)4(NO3)3·H2O, s, 298.2 K] and[Er(Ala)4(NO3)3·H2O, s,298.2 K] at 298.2 K have been determined to be ΔfHm0 [Nd(Ala)4(NO3)3·H2O,s, 298.2 K]=–3867.2 kJ mol–1, and ΔfHm0 [Er(Ala)4(NO3)3·H2O, s, 298.2 K]=–3821.5 kJ mol–1.

NEW OBSERVATIONS ON THE ANATOMY OF THE FOSSIL CALCAREOUS ALGA SUBTERRANIPHYLLUM ELLIOTT

New specimens of Subterraniphyllum thomasii Elliott collected from the Oligocene Molare Formation outcropping close to Alessandria (northern Italy) and studied in thin sections and by SEM showed that primary pit-connections, cell fusions, uniporate conceptacles and geniculate branches were present. These new observations collectively confirm the placement of S. thomasii within the geniculate Corallinaceae. Although S. thomasii share many diagnostic characters with the Corallinoideae, in particular with the tribe Corallineae (apical position of uniporate conceptacles, number of medullary cell layers) and some similarity with the Metagoniolithoideae (medullary cells gradually merging into the cortical cells) the lack of information on genicula and the observed details of insertion of branches do not allow to determine the suprageneric disposition of S. thomasii .

A thermochemical study of the reaction of CuCl 2·2H 2O with 8-hydroxyquinoline

The solid-state coordination reaction of CuCl 2·2H 2O with 8-hydroxyquinoline (HQ): HQ(s)+CuCl 2·2H 2O(s)→Cu(HQ)Cl 2(s)+2H 2O(l) has been studied by solution calorimetry. The molar dissolution enthalpies of the reactants and the products in 3 mol l −1 HCl of the solid–solid coordination reaction have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpy of [Cu(HQ)Cl 2,s,298.15 K] at 298.15 K has been derived: Δ f H m Θ(Cu(HQ)Cl 2,s,298.15 K)=−340.12 kJ mol −1.

Study on thermodynamic properties of a double salt, K 2Mg(IO 3) 4·2H 2O

The standard molar enthalpy of solution of double salts, K 2Mg(IO 3) 4·2H 2O(s), in water has been measured by solution calorimetry. From that value, combined with auxiliary values, the standard molar formation enthalpy has been derived: Δ f H m Θ (K 2Mg(IO 3) 4·2H 2O,s,298.2 K = −2510.69 kJ mol −1. The standard free energy {Δ f G m Θ (K 2Mg(IO 3) 4·2H 2O,s,298.2 K) = −2061.72 J K mol −1} and the absolute entropy ( S m Θ(K 2Mg(IO 3) 4·2H 2O,s,298.2 K) = 258.36 J K −1 mol −1 were also calculated.

Products of the gas‐phase reactions of the OH radical with n‐butyl methyl ether and 2‐isopropoxyethanol: Reactions of ROC(??) < radicals

The products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol in the presence of NO have been investigated at 298 ± 2 K and 740 Torr total pressure of air by gas chromatography and in situ atmospheric pressure ionization tandem mass spectrometry. The products observed from n-butyl methyl ether were methyl formate, propanal, butanal, methyl butyrate, and CH3C(O)CH2CH2OCH3 and/or CH3CH2C(O)CH2OCH3, with molar formation yields of 0.51 ± 0.11, 0.43 ± 0.06, 0.045 ± 0.010, ∼0.016, and 0.19 ± 0.04, respectively. Additional products of molecular weight 118, 149 and 165 were observed by API-MS/MS analyses, with those of molecular weight 149 and 165 being identified as organic nitrates. The products observed and quantified from 2-isopropoxyethanol were isopropyl formate and 2-hydroxyethyl acetate, with molar formation yields of 0.57 ± 0.05 and 0.44 ± 0.05, respectively. For both compounds, the majority of the reaction products and reaction pathways are accounted for, and detailed reaction mechanisms are presented. The results of this product study are combined with previous literature product data to investigate the tropospheric reactions of R1R2C(Ȯ)OR radicals formed from ethers and glycol ethers, leading to a revised estimation method for the calculation of reaction rates of alkoxy radicals. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 501–513, 1999

FT-IR product study of the photo-oxidation of dimethyl sulfide: Temperature and O2 partial pressure dependence

The products of the OH-radical initiated oxidation of dimethyl sulfur (DMS) have been investigated under NOx free conditions using the photolysis of H2O2 as the OH radical source and FT-IR spectroscopy to monitor reactants and products at 1000 mbar total pressure (N2+O2). The products were investigated as a function of the temperature (284, 295 and 306±2 K) and the O2 partial pressure (20, 200 and 500 mbar). Dimethyl sulfoxide (DMSO), SO2 and methane sulfonic acid (MSA: CH3SO3H) were the major sulfur-containing products and evidence has been found for the formation of methane sulfinic acid (MSIA: CH3S(O)OH) in considerable yield. The variation of the formation of DMSO and SO2 with temperature and O2 partial pressure is consistent with a mechanism involving both addition and abstraction channels. The molar formation yields of DMSO support that a major fraction of the OH-DMS adduct formed in the addition channel reacts with O2 to form DMSO. Due to the uncertainty in the literature rate coefficients used for the corrections in the formation yield of DMSO the possibility of other channels cannot be completely excluded. High overall molar formation yields of SO2 have been measured, suggesting that further oxidation of the products in both the addition and abstraction channels result mainly in SO2 production under the NOx free conditions employed in the experiments. Consideration is made of the implications of the results for the atmospheric oxidation of DMS under conditions of low NOx such as occur in the remote marine boundary layer.

Products of the gas-phase reactions of the OH radical withn-butyl methyl ether and 2-isopropoxyethanol: Reactions of ROC(??) < radicals

The products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol in the presence of NO have been investigated at 298 ± 2 K and 740 Torr total pressure of air by gas chromatography and in situ atmospheric pressure ionization tandem mass spectrometry. The products observed from n-butyl methyl ether were methyl formate, propanal, butanal, methyl butyrate, and CH3C(O)CH2CH2OCH3 and/or CH3CH2C(O)CH2OCH3, with molar formation yields of 0.51 ± 0.11, 0.43 ± 0.06, 0.045 ± 0.010, ∼0.016, and 0.19 ± 0.04, respectively. Additional products of molecular weight 118, 149 and 165 were observed by API-MS/MS analyses, with those of molecular weight 149 and 165 being identified as organic nitrates. The products observed and quantified from 2-isopropoxyethanol were isopropyl formate and 2-hydroxyethyl acetate, with molar formation yields of 0.57 ± 0.05 and 0.44 ± 0.05, respectively. For both compounds, the majority of the reaction products and reaction pathways are accounted for, and detailed reaction mechanisms are presented. The results of this product study are combined with previous literature product data to investigate the tropospheric reactions of R1R2C(Ȯ)OR radicals formed from ethers and glycol ethers, leading to a revised estimation method for the calculation of reaction rates of alkoxy radicals. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 501–513, 1999

Thermochemistry of Hf-Zirconolite, CaHf Ti2O7

AbstractThe formation enthalpy, - 3752.3 ± 4.7 kJ·mol−1, of Hf-zirconolite, CaHfTi2O7, was obtained using high temperature oxide-melt solution calorimetry. Combined with heat capacity data obtained using low temperature adiabatic calorimetry we report the heat capacity (Cp) and the standard molar formation energetics (ΔH°f. elements, Δ S°T, and ΔG°f. elements)for Hf-zirconolite from T = 298.15 K to T = 1500 K. Comparison of Hf-zirconolite with Zr-zirconolite is made.

Products of the Gas-Phase Reactions of the OH Radical with 1-Methoxy-2-propanol and 2-Butoxyethanol

Glycol ethers are used as solvents and are hence liable to be released to the atmosphere, where they react and contribute to the formation of photochemical air pollution. In this work, products of the gas-phase reactions of the OH radical with 1-methoxy-2-propanol and 2-butoxyethanol in the presence of NO have been investigated at 298 {+-} 2K and 740 Torr total pressure of air by gas chromatography, in situ Fourier transform infrared spectroscopy, and in situ atmospheric pressure ionization tandem mass spectrometry. The products observed from 1-methoxy-2-propanol were methyl formate, methoxyacetone, and acetaldehyde with molar formation yields of 0.59 {+-} 0.05, 0.39 {+-} 0.04, and 0.56 {+-} 0.07, respectively. The products observed and quantified from 2-butoxyethanol were n-butyl formate, 2-hydroxyethyl formate, propanal, 3-hydroxybutyl formate, and an organic nitrate with molar formation yields of 0.57 {+-} 0.05, 0.22 {+-} 0.05, 0.21 {+-} 0.02, 0.07 {+-} 0.03, and 0.10 {+-} 0.03, respectively. An additional product of molecular weight 132, attributed to one or more hydroxycarbonyl products, was also observed from the 2-butoxyethanol reaction by atmospheric pressure ionization mass spectrometry. For both glycol ethers, the majority of the reaction products and reaction pathways are accounted for, and detailed reaction mechanisms are presented which accountmore » for the observed products.« less

The Reactions of Selected Acetates with the OH Radical in the Presence of NO: Novel Rearrangement of Alkoxy Radicals of Structure RC(O)OCH(Ȯ)Ŕ

Products of the gas-phase reactions of the OH radical with ethyl acetate, isopropyl acetate, tert-butyl acetate in the presence of NO were investigated using in situ Fourier transform infrared spectroscopy and gas chromatography. The products identified and their molar formation yields (corrected for secondary reactions with the OH radical) were acetic acid (0.96 ± 0.08) from ethyl acetate; acetic acid (0.09 ± 0.03), acetic anhydride (0.76 ± 0.07), and acetone (0.24 ± 0.02) from isopropyl acetate; and acetic anhydride (0.49 ± 0.05) and acetone (0.20 ± 0.02) from tert-butyl acetate. Consideration of the potential reaction pathways of the intermediate alkoxy radicals leads to the conclusion that alkoxy radicals of structure RC(O)OCH(Ȯ)Ŕ can undergo a rapid rearrangement and decomposition (α-ester rearrangement) to RC(O)OH plus ŔĊO, presumably via a five-membered ring transition state. However, our product studies provided no evidence for the analogous β-ester rearrangement proceeding via a six-membered tran...

Expression of GDNF and its receptors in developing tooth is developmentally regulated and suggests multiple roles in innervation and organogenesis.

Glial cell line-derived neurotrophic factor (GDNF) is a recently identified survival factor for several populations of neurons in the central and peripheral nervous system that also regulates kidney development. To study the roles of GDNF in the regulation of tooth innervation and formation, we analyzed by in situ hybridization the expression patterns of GDNF and its receptors Ret, GDNF family receptor alpha-1 (GFRalpha-1), and GFRalpha-2 from the initiation of first molar formation to the completion of crown morphogenesis. At the time of trigeminal axon ingrowth, GDNF mRNAs were expressed in the mesenchyme around the tooth germ (i.e., target field of the dental innervation), suggesting that it is involved in the regulation of the embryonic tooth innervation. This hypothesis was supported by the ability of GDNF to induce neurite outgrowth from embryonic day 12 (E12) to E15 trigeminal ganglia. This timing correlated with the appearance of Ret in the subset of cells in the trigeminal ganglion at E12, whereas GFRalpha-1 and GFRalpha-2 receptors were constantly expressed in trigeminal ganglion during E11-E15. After birth, GDNF expression showed apparent correlation with the ingrowth and presence of trigeminal nerve fibers in the tooth, suggesting that GDNF is involved in the regulation of innervation of the dental papilla and dentin postnatally. Ret, GFRalpha-1, and GFRalpha-2 mRNAs were expressed in the dental epithelial and mesenchymal cells at stages when epithelial-mesenchymal signalling regulates critical steps of tooth morphogenesis. Ret and GFRalpha-2 were colocalized in the dental mesenchyme during bud and cap stages. Expression of GFRalpha-1 associated with the formation of the epithelial enamel knot, which is a putative embryonic signalling center regulating tooth shape. During postnatal development, GDNF and its receptors were expressed in dental papilla mesenchyme. In addition, GDNF and GFRalpha-1 transcripts were seen in the preodontoblasts and odontoblasts, suggesting that they may be involved in differentiation and maintenance of functional properties of the odontoblasts. Taken together, these results suggest that GDNF acts as a target-derived neurotrophic factor during tooth innervation. In addition, GDNF and its receptors may have nonneuronal organogenetic functions during tooth morphogenesis.

Neurotrophin mRNA expression in the developing tooth suggests multiple roles in innervation and organogenesis.

To analyze the roles of neurotrophins during early development of rat teeth, we studied the expression of neurotrophin mRNAs from the initiation of first molar formation to the completion of crown morphogenesis. With RNAase protection assay all neurotrophin mRNAs were detected in embryonic teeth. In situ hybridization analysis revealed developmentally changing, distinct expression patterns for nerve growth factor (NGF) and neurotrophin-3 (NT-3), which were shown not to be regulated by or dependent on peripheral innervation. NGF mRNAs appeared in the mesenchymal target field of the tooth at the time of the trigeminal axon ingrowth (embryonic days 14-15: E14-E15), and they were also present along the pathway taken by growing trigeminal axons. NT-4/5 mRNAs were uniformly expressed in all epithelial cells, but brain-derived neurotrophic factor (BDNF) transcripts were not detected. All neurotrophins induced neurite outgrowth from E13-E16 trigeminal ganglion explants. These results suggest that NGF is involved in the guidance of trigeminal axons to embryonic teeth. In postnatal teeth, expression of NGF mRNAs, but not other neurotrophins, correlated with trigeminal axon ingrowth, proposing that NGF is involved in local sprouting and establishment of the final innervation pattern of the dental papilla and dentin. These results suggest that NGF is required for tooth innervation and that other neurotrophins may also have regulatory roles. In addition, the expression patterns of NGF, NT-3, and NT-4/5 as well as of neurotrophin receptors suggest that the neurotrophin system may also serve non-neuronal functions during tooth development.

A thermochemical study of Cs 2MCl 4 complexes

The standard molar formation enthalpies of Cs 2MCl 4 (M is Zn(II) and Cu(II) are determined from the enthalpies of dissolution ( Δ s H ⊖ m ) of [2CsCl(s) + MCl 2(s)] and Cs 2MCl 4(s) in 0.03 mol l −1 H 2SO 4 solvent, respectively, at 298.2 K, as: Δ fH⊖ m( Cs 2ZnCl 4, s , 298.2 K=−1340.46 kJ mol− Δ fH⊖ m( Cs 2ZnCl 4, s , 298.2 K=−1129.04 kJ mol−

A thermochemical study of the reaction of salicylaldoxime with anhydrous nickel(II) and cobalt(II) acetate

The solid-state coordination reaction: 2HSAO(s) + Ni(Ac) 2(s) → Ni(SAO) 2(s) + 2HAc(g) 2HSAO(s) + Co(Ac) 2·4H 2O(s) → Co(SAO) 2·2H 2O(s) + 2HAc(g) + 2H 2O(g) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in a certain solvent (for one reaction is in 6 mol l −1 HCl and another in a mixed solution consisting of DMSO and DMF) of this two solid-solid coordination reactions have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpies of [Co(SAO) 2·2H 2O, s, 298.2 K] and [Ni(SAO) 2, s, 298.2 K] at 298.2 K have been determined to be Δ f H θ m [Co(SAO) 2·2H 2O, s, 298.2 K] = −957.205 kJ mol −1 and Δ f H θ m [Ni(SAO) 2, s, 298.2 K] = −403.336 kJ mol −1.

Scalar-relativistic effects in solids in the framework of a Douglas-Kroll transformed Dirac-Coulomb Hamiltonian

The Douglas-Kroll transformed Dirac-Coulomb Hamiltonian is used to described scalar-relativistic effects in solids. A Hartree-Fock approximation with periodic boundary conditions makes it feasible to use methods originally developed for atoms and molecules to solve the corresponding equations for crystalline systems. The implementation is realized within the CRYSTAL program. Scalar-relativistic effects in silver compounds of FCC structure such as AgF, AgCl, AgBr and Ag are investigated for the molar formation energy, the lattice parameter, the isothermal bulk modulus and the pressure derivative.

Tropospheric Degradation Products of Novel Hydrofluoropolyethers

The Cl atom-initiated photooxidations of the hydrofluoropolyethers (HFPEs) HCF 2 OCF 2 OCF 2 CF 2 OCF 2 H, HCF 2 OCF 2 CF 2 -OCF 2 H, and HCF 2 OCF 2 OCF 2 H in air produced C(O)F 2 as the only carbon-containing product, with observed average C(O)F 2 molar formation yields of 4.73, 3.77, and 2.82, respectively. The C(O)F 2 molar formation yields during the early stages of the reactions were observed to be closer to the number of C atoms in each parent HFPE. On the basis of current knowledge concerning the degradation pathways of hydrofluorocarbons and hydrochlorofluorocarbons, it is expected that C(O)F 2 will also be produced with near unit yield per C atom from the above HFPEs in the troposphere, where loss processes would be initiated primarily by reaction with OH radicals. The rate constants for reaction with the Cl atom at 298 ± 2 K were determined for the HFPEs by a relative rate method that employed CF 3 CF 2 H as the reference compound [k(Cl + CF 3 CF 2 H) = (2.4 ± 0.51 x 10 -16 cm 3 molecule -1 s -1 ], with measured values of (in units of 10 -17 cm 3 molecule -1 s -1 ) HCF 2 OCF 2 OCF 2 CF 2 -OCF 2 H, 3.6 ± 0.8; HCF 2 OCF 2 CF 2 OCF 2 H, 4.5 ± 1.0; and HCF 2 -OCF 2 OCF 2 H, 5.0 ± 1.1.

Cambrian trilobites from Northern Victoria Land, Antarctica, and their stratigraphic implications

Abstract Fifty‐four trilobite taxa from 15 new localities in the Bowers Terrane of Northern Victoria Land, including the first fossils from Molar Formation, are described. The fossils indicate an age range from late Middle Cambrian (Boomerangian or older) to mid Late Cambrian (late Idamean). At Reilly Ridge, the Spurs Formation crops out in a number of fault‐bounded slices; the new fossils indicate marked lateral facies contrasts between slices and suggest considerable lateral displacement along the bounding faults. At Houliston Glacier, trilobites of Mindyallan age in Molar Formation imply that the boundary between the Molar and Spurs Formations is strongly time transgressive. New species described in this paper are Reillopleura braddocki gen. et sp. nov. and Notoaphelaspis horizontalis sp. nov. Faunal affinities are mainly with the Ellsworth Mountains (West Antarctica), western Queensland, and China.

OLIGOCENE CORAL AND ALGAL REEF AND RELATED FACIES OF VALZEMOLA (SAVONA, NW ITALY)

The terrigenous and carbonate sediments of the transgressive Oligocene cycle of the Tertiary Piedmont Basin outcropping in the area of Valzemola(Savona, western Liguria, Northwest Italy) and which are referable to the Molare Formation are analysed. The terrigenous sequence, represented by breccias, conglomerates and sandstones, overlies with an angular unconformity dolomitic or calcareous-dolomitic lithologies referable to the San Pietro dei Monti Dolomite Formation. These sequences are locally characterized by rich associations of coralline algae and corals, which by providing a stable substrate allowed the development of a true build up. Subsequently the bioherm was suffocated by fluvial sandstone and conglomerate. This may be associated with an intensification in the amount of terrigenous material being brought into the basin. A progressive shallowing continues until the introduction of conditions suitable for calcareous deposition in an intertidal or supratidal environment. The analysis of this deposit was carried out by examining seven stratigraphic sections. The paleoecological study of the coral fauna and the algal assemblage, the latter characterized by the significant presence either of the genus Lithophyllum , or of Lithothamnion , allowed some hypothesis on the environmental conditions which characterized this sector during the Late Oligocene. Nine different facies could be shown, from those seven directly connected to the and two to nearshore environments proving a regressive phase. Facies I: conglomeratic-sandstone representing a stage of colonization in a dominantly terrigenous environment. Facies II: coral framestone, representing a stage of diversification (an front near to the reef crest). Facies III: coral bafflestone representing a colonization stage in an inner slope. Facies IV: coral bindstone representing a stage of domination in a reef crest environment. Facies V: coral bindstone alternating with floatstone, gives evidence of a colonization stage in a carbonate environment. Facies VI: coral and algae floatstone, representing a facies of accumulated debris. Facies VII: coral rudstone, representing an accumulation facies comparable with that of the rubble & pavement zone of the back reef. Facies VIII: conglomerates and sands of a shallow marine environment, represent a regressive sequence. Facies IX: massive limestones with undulated-zoned structures, rhizoliths, calcite veins and pisoliths, evidence of an intertidal or supratidal environment.

LITHOPHYLLUM IPPOLITOI . A NEW SPECIES OF CORALLINE ALGAE FROM TERTIARY PIEDMONT BASIN

A new species of the genus Lithophyllum ( Lithophyllum ippolitoi ) was discovered in the Oligocene section of Toleto (Molare Formation, Tertiary Piedmont Basin). The holotype overgrows a coral colony, and is characterised by morphological features and dimensions of cells that are clearly different from those of the other recorded species of Lithophyllum .

Expression of growth hormone receptor by immunocytochemistry in rat molar root formation and alveolar bone remodeling.

Growth hormone (GH) may regulate tooth formation and bone remodeling associated with tooth eruption. This study reports the distribution of growth hormone receptor/binding protein in developing rat molars and adjacent alveolar bone by immunocytochemistry using well-characterized anti-growth hormone receptor monoclonal antibodies. These tissues represent an excellent model for studying the ontogenic changes that occur in odontogenic and osteogenic cells, as these cells are found in linear arrays displaying the various stages of morphological and functional differentiation, and differentiated function. Immunoreactivity was first seen in precementoblasts in contact with the epithelial root sheath, and preodontoblasts. However, growth hormone receptor immunoreactivity was associated primarily with the cytoplasm of odontogenic and osteogenic cells forming their respective matrices. Thus, cementoblasts and odontoblasts at sites of new matrix formation showed intense immunoreactivity whereas cementocytes and mature odontoblasts at later stages of tooth development were nonreactive. Osteoblasts engaged in intramembranous ossification in the alveolar bone were positive, although osteocytes and endosteal cells were immunonegative. Osteoclasts at sites of alveolar bone remodeling resorption were also immunopositive. These patterns of receptor expression parallel the ontogenic sequences of odontogenic and osteogenic cells and suggest that GH promotes the functional state of these cells. Our results also imply that GH may influence differentiation or differentiated functions associated with odontogenesis, osteogenesis, and bone remodeling independent of systemic insulin-like GF-I.