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Nebiha Hilal Bilge, Selin Yeşiltepe, Kübra Törenek Ağırman, Fatma Çağlayan, Osman Murat Bilge
BACKGROUND: This study was performed to evaluate the prevalence of all types and subtypes of dental anomalies among 6 to 40 year-old patients by using panoramic radiographs. MATERIALS AND METHODS: This cross-sectional study was conducted by analyzing digital panoramic radiographs of 1200 patients admitted to our clinic in 2014. Dental anomalies were examined under 5 types and 16 subtypes. Dental anomalies were divided into five types: (a) number (including hypodontia, oligodontia and hyperdontia); (b) size (including microdontia and macrodontia); (c) structure (including amelogenesis imperfecta, dentinogenesis imperfecta and dentin dysplasia); (d) position (including transposition, ectopia, displacement, impaction and inversion); (e) shape (including fusion-gemination, dilaceration and taurodontism); RESULTS: The prevalence of dental anomalies diagnosed by panoramic radiographs was 39...
September 21, 2017: Folia Morphologica (Warsz)
Justin T Barry, Daniel J Berg, David R Tyler
This study reports a method for correlating the radical recombination efficiencies (FcP) of geminate radical cage pairs to the properties of the solvent. Although bulk viscosity (macroviscosity) is typically used to predict or interpret radical recombination efficiencies, the work reported here shows that microviscosity is a much better parameter. The use of microviscosity is valid over a range of different solvent system types, including nonpolar, aromatic, polar, and hydrogen bonding solvents. In addition, the relationship of FcP to microviscosity holds for solvent systems containing mixtures of these solvent types...
September 20, 2017: Journal of the American Chemical Society
Katharina Boguslawski, Pawel Tecmer
Wave functions restricted to electron-pair states are promising models to describe static/nondynamic electron correlation effects encountered, for instance, in bond-dissociation processes and transition-metal and actinide chemistry. To reach spectroscopic accuracy, however, the missing dynamic electron correlation effects that cannot be described by electron-pair states need to be included a posteriori. In this article, we extend the previously presented perturbation theory models with an Antisymmetric Product of 1-reference orbital Geminal (AP1roG) reference function that allow us to describe both static/nondynamic and dynamic electron correlation effects...
September 18, 2017: Journal of Chemical Theory and Computation
Ewa Pastorczak, Jun Shen, Michal Hapka, Piotr Piecuch, Katarzyna Pernal
Non-covalent interactions between molecules with stretched intramonomer covalent bonds are a fascinating, yet little studied area. This shortage of information stems largely from the inability of most of the commonly used computational quantum chemistry methods to accurately describe weak long-range and strong non-dynamic correlations at the same time. In this work, we propose a geminal-based approach, abbreviated as EERPA-GVB, capable of describing such systems in a robust manner using relatively inexpensive computational steps...
September 18, 2017: Journal of Chemical Theory and Computation
Vsevolod I Borovkov
Spin correlation effects in the geminate recombination of radical ion pairs in irradiated highly polar liquids are typically believed to be negligible due to a high escape probability for the ions. This report presents the results of an exploratory study of organic polar solvents aimed at the searching for, and estimating the magnitude of, the time-resolved magnetic field effects (TR MFEs) in the delayed radiation-induced fluorescence from diluted solutions of a luminophore. It has been found that upon the high-energy irradiation of the solutions in polar liquids, such as dichloroethane (ε≈10), methanol (ε≈33), acetonitrile (ε≈37), dimethyl formamide (ε≈37), dimethyl sulfoxide (ε≈47), ethylene carbonate (ε≈89), substantial spin coherence effects in the delayed fluorescence can be observed within a time range up to ~100 ns...
September 15, 2017: Journal of Physical Chemistry. B
Frank Seela, Xiurong Guo, Peter Leonard, Sachin Asaram Ingale
The stability of silver mediated "dC-dC" base pairs relies not only on the structure of the nucleobase but also is sensitive to structural modification on the sugar moiety. 2'-Fluorinated 2'-deoxycytidines with fluorine atoms in the arabino (up) and the ribo (down) configuration, as well as with geminal fluorine substitution (anticancer drug gemcitabine) and the novel fluorescent phenylpyrrolo-gemcitabine (phPyrGem) were synthesized. All nucleosides display the recognition face of naturally occurring 2'-deoxycytidine...
September 14, 2017: Chemistry: a European Journal
A A Kipriyanov, A R Melnikov, D V Stass, A B Doktorov
Exciplex generation under optical and X-ray excitation in identical conditions is experimentally compared using a specially chosen model donor-acceptor system, anthracene (electron acceptor) and N,N-dimethylaniline (electron donor) in non-polar solution, and the results are analyzed and interpreted based on analytically calculated luminescence quantum yields. Calculations are performed on the basis of kinetic equations for multistage schemes of bulk exciplex production reaction under optical excitation and combination of bulk and geminate reactions of radical ion pairs under X-ray excitation...
September 7, 2017: Journal of Chemical Physics
Evi R M Habraken, Lars C Mens, Martin Nieger, Martin Lutz, Andreas W Ehlers, J Chris Slootweg
The reactivity of the geminal phosphinoborane tBu2PCH2BPh2 towards terminal alkynes, nitriles and nitrilium salts is investigated. Terminal alkynes react via C-H bond splitting (deprotonation) resulting in the formation of phosphonium borates. In contrast, both nitriles and nitrilium salts undergo addition reactions resulting in the formation of five-membered heterocycles. All compounds were characterized by multinuclear NMR spectroscopy, and single-crystal X-ray structure determinations. Insight into the reaction mechanisms was gained by DFT calculations...
September 28, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Klaus Banert, Christian Berndt, Kevin Weigand
α-Azido alcohols are generated by treating aldehydes with hydrazoic acid in chloroform. These adducts are transformed into geminal azido-halo compounds through the reaction with phosphorus trichloride or phosphorus tribromide, whereas α-azidoalkyl esters are isolated after interaction with acyl chlorides.
September 6, 2017: Organic Letters
Andrew M Camp, Matthew R Kita, Javier Grajeda, Peter S White, Diane A Dickie, Alexander J M Miller
A protocol for identifying ligand binding modes in a series of iridium pincer complexes bearing hemilabile aza-crown ether ligands has been developed using readily accessible NMR methods. The approach was tested on a collection of 13 structurally diverse pincer-crown ether complexes that include several newly characterized species. New synthetic routes enable facile interconversion of coordination modes and supporting ligands. Detailed structural assignments of five complexes reveal that the difference in chemical shift (Δδ) between geminal protons in the crown ether is influenced by diamagnetic anisotropy arising from halides and other ligands in the primary coordination sphere...
September 5, 2017: Inorganic Chemistry
Viktorija Glembockyte, Gonzalo Cosa
Here we report transient absorption studies on the ground-state recovery dynamics of the single-molecule fluorophore Cy3B in the presence of four different photostabilizing agents, namely β-mercaptoethanol (β-ME), Trolox (TX), n-propyl gallate (n-PG), and ascorbic acid (AA). These are triplet-state quenchers that operate via photoinduced electron transfer (PeT). While quantitative geminate recombination was recorded following PeT for β-ME (∼100%), for Trolox, n-propyl gallate, and ascorbic acid the extent of geminate recombination was >48%, >27%, and >13%, respectively...
September 8, 2017: Journal of the American Chemical Society
Rafaela S Fontenele, Natalia S Lamas, Cristiano Lacorte, Ana Luiza M Lacerda, Arvind Varsani, Simone G Ribeiro
Viruses in the family Geminiviridae have single-stranded DNA genomes encapsulated in geminate icosahedral particles. High throughput sequencing (HTS) for metagenomic approaches are being extensively used for the identification of known and novel viruses. Using a HTS approach, we identified a novel geminivirus in a tomato (Solanum lycopersicum) sample and a Cleome sp. sample collected in the midwest region of Brazil. The genomes from the two samples share 99.96% identity and ∼61-63% to genomes in the genus Capulavirus...
August 23, 2017: Virus Research
Zhongbao Jian, Gerald Kehr, Constantin G Daniliuc, Birgit Wibbeling, Gerhard Erker
The secondary aryl-P(H) phosphanyl substituted tert-butylacetylenes 7a,b (aryl: Mes or Mes*) undergo hydroboration with [HB(C6F5)2] to give the geminal vinylidene-bridged P/B Lewis pairs 8a,b. The treatment of 8a,b with benzonitrile, N-sulfinylaniline, and phenyl isothiocyanate, respectively, gives the addition products 12a,b, 13a,b, and 14 with proton transfer from the phosphorus to the more basic nitrogen site. The reaction of the FLPs 8a,b with carbon dioxide yields a doubly boron bonded addition product...
September 12, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Masahito Murai, Ryuji Taniguchi, Naoki Hosokawa, Yusuke Nishida, Hiroko Mimachi, Toshiyuki Oshiki, Kazuhiko Takai
Stabilization by a silyl group on the methylene carbon and a diamine ligand led to the isolation of gem-dichromiomethane species. X-ray crystallography confirmed the identity of the structure of this rare example of reactive gem-dimetalloalkane species. The isolated gem-dichromiomethane complex acted as a storable silylmethylidene carbene equivalent, with reactivity that could be changed dramatically upon addition of a Lewis acid (ZnCl2) and a base (TMEDA) to promote both silylalkylidenation of polar aldehydes and silylcyclopropanation of nonpolar alkenes...
September 5, 2017: Journal of the American Chemical Society
Ling Liu, Xiuhui Zhang, Zesheng Li, Yunhong Zhang, Maofa Ge
Oxocarboxylic acids are one of the most important organic species found in secondary organic aerosols and can be detected in diverse environments. But the hydration of oxocarboxylic acids in the atmosphere has still not been fully understood. Neglecting the hydration of oxocarboxylic acids in atmospheric models may be one of the most important reasons for the significant discrepancies between field measurements and abundance predictions of atmospheric models for oxocarboxylic acids. In the present paper, glyoxylic acid, as the most abundant oxocarboxylic acids in the atmosphere, has been selected as an example to study whether the hydration process can occur in the atmosphere and what the kinetic process of hydration is...
November 2017: Chemosphere
Anthony Pujol, Mathieu Lafage, Feriel Rekhroukh, Nathalie Saffon-Merceron, Abderrahmane Amgoune, Didier Bourissou, Noel Nebra, Marie Fustier-Boutignon, Nicolas Mézailles
The first Au(III) carbene complex was prepared by reacting a geminal dianion with a (P,C) cyclometalated Au(III) precursor. Its structure and bonding situation have been thoroughly investigated by experimental and computational means. The presence of a high-energy highest occupied molecular orbital (HOMO) centered at the carbene center suggests nucleophilic character for the Au(III) carbene complex. This unprecedented feature was confirmed by reactions with two electrophiles (PhNCS and CS2 ), resulting in two types of C=C coupling reactions...
August 7, 2017: Angewandte Chemie
Elisa Collado-Fregoso, Samantha N Hood, Safa Shoaee, Bob C Schroeder, Iain McCulloch, Ivan Kassal, Dieter Neher, James R Durrant
In this Letter, we study the role of the donor:acceptor interface nanostructure upon charge separation and recombination in organic photovoltaic devices and blend films, using mixtures of PBTTT and two different fullerene derivatives (PC70BM and ICTA) as models for intercalated and nonintercalated morphologies, respectively. Thermodynamic simulations show that while the completely intercalated system exhibits a large free-energy barrier for charge separation, this barrier is significantly lower in the nonintercalated system and almost vanishes when energetic disorder is included in the model...
August 16, 2017: Journal of Physical Chemistry Letters
Kishor S Gavale, Shrawan R Chavan, Navanath Kumbhar, Sonali Kawade, Pooja Doshi, Ayesha Khan, Dilip D Dhavale
A simple strategy for the synthesis of α-geminal disubstituted pyrrolidine iminosugars 3a-c and their C-4 fluorinated derivatives 4a-c has been described from d-glucose. The methodology involves the Corey-Link and Jocic-Reeve reaction with 3-oxo-α-d-glucofuranose and nucleophilic displacement reaction to get the furanose fused pyrrolidine ring skeleton with requisite CH2OH/CO2H functionalities at C-3. The fluorine substituent in target molecules was introduced by nucleophilic displacement of -OTf in 9a/9c with CsF...
July 14, 2017: Bioorganic & Medicinal Chemistry
Rocco Romagnuolo, Corey A Scipione, Santica M Marcovina, Matthew Gemin, Nabil G Seidah, Michael B Boffa, Marlys L Koschinsky
Elevated plasma concentrations of lipoprotein(a) (Lp(a)) are a causal risk factor for cardiovascular disease. The mechanisms underlying Lp(a) clearance from plasma remain unclear, which is an obvious barrier to the development of therapies to specifically lower levels of this lipoprotein. Recently, it has been documented that monoclonal antibody inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9) can lower plasma Lp(a) levels by 30%. Since PCSK9 acts primarily through the low density lipoprotein receptor (LDLR), this result is in conflict with the prevailing view that the LDLR does not participate in Lp(a) clearance...
2017: PloS One
Tim Albes, Alessio Gagliardi
In bulk-heterojunction organic solar cells the low permittivity in combination with the spatial and energetic disorder of the organic materials lead to a complex behavior of charge carriers within the active layer. Charges originate from exciton splitting at the heterojunction interface and the successive interplay between mutual Coulomb interactions and transport through the disordered organic can lead to insufficient separation from the interface, increased interface densities with respect to the bulk regions and, hence, affect recombination...
August 9, 2017: Physical Chemistry Chemical Physics: PCCP
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