Biometric Analysis of C-shaped Root Canals in Mandibular Second Molars Using Cone-Beam Computed Tomography

Introduction: The configuration of C-shaped root canals, root canal wall thickness and orientation of the thinnest area using CBCT in mandibular second molars were assessed.  Methods and Materials: Seventy five CBCT scans were evaluated. Axial sections were evaluated to determine the configuration of C-shaped canals in the coronal, middle and apical regions. The root canal path from the orifice to the apex, the thinnest root canal wall and its orientation were all determined. Data were analyzed using one-way ANOVA and post hoc Tukey’s test. Results: The most common configurations were Melton's type I in the coronal and middle and types I and IV in the apical region. The mean thicknesses of the thinnest root canal wall were 1.94±0.43, 1.42±0.57 and 1.10±0.52 mm in the coronal, middle and apical regions, respectively. The lingual wall was the thinnest wall in the coronal, middle and apical regions and it was thinner in the apical than in the middle and coronal regions. The lingual wall was thinner in the middle third of the mesial root compared to the distal root (P<0.05). Conclusion: The lingual wall was the thinnest in C-shaped root canals of mandibular second molars of an Iranian population. Type, number and pathway of canals may vary from the orifice to the apex.Keywords: Biometric Identification; C-shape Root Canal; Cone-Beam Computed Tomograph

Molecular structure retrieval directly from laboratory-frame photoelectron spectra in laser-induced electron diffraction

Ubiquitous to most molecular scattering methods is the challenge to retrieve bond distance and angle from the scattering signals since this requires convergence of pattern matching algorithms or fitting methods. This problem is typically exacerbated when imaging larger molecules or for dynamic systems with little a priori knowledge. Here, we employ laser- induced electron diffraction (LIED) which is a powerful means to determine the precise atomic configuration of an isolated gas-phase molecule with picometre spatial and attose- cond temporal precision. We introduce a simple molecular retrieval method, which is based only on the identification of critical points in the oscillating molecular interference scattering signal that is extracted directly from the laboratory-frame photoelectron spectrum. The method is compared with a Fourier-based retrieval method, and we show that both methods correctly retrieve the asymmetrically stretched and bent field-dressed configuration of the asymmetric top molecule carbonyl sulfide (OCS), which is confirmed by our quantum- classical calculations.J.B. and group acknowledge financial support from the European Research Council for ERC Advanced Grant “TRANSFORMER” (788218), ERC Proof of Concept Grant “miniX” (840010), FET-OPEN “PETACom” (829153), FET-OPEN “OPTOlogic” (899794), Laserlab- Europe (EU-H2020 654148), MINECO for Plan Nacional FIS2017-89536-P; AGAUR for 2017 SGR 1639, MINECO for “Severo Ochoa” (SEV-2015-0522), Fundació Cellex Barce- lona, CERCA Programme/Generalitat de Catalunya, the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314, and the Alexander von Humboldt Foundation for the Friedrich Wilhelm Bessel Prize. J.B. and K.A. acknowledge the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314, B.B. acknowledges Severo Ochoa” (SEV-2015-0522), and A.S. acknowledges funding from the Marie Sklodowska-Curie grant agreement No. 641272. S.J.W. and C.D.L. are supported in part by Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy under Grant No. DE-FG02- 86ER13491. M.R. and S.G. highly acknowledges support from the European Research Council (ERC) for the ERC Consolidator Grant QUEM-CHEM (772676).Peer ReviewedPostprint (published version

Laser-induced electron diffraction of the ultrafast umbrella motion in ammonia

Visualizing molecular transformations in real-time requires a structural retrieval method with Ångström spatial and femtosecond temporal atomic resolution. Imaging of hydrogen-containing molecules additionally requires an imaging method that is sensitive to the atomic positions of hydrogen nuclei, with most methods possessing relatively low sensitivity to hydrogen scattering. Laser-induced electron diffraction (LIED) is a table top technique that can image ultrafast structural changes of gas-phase polyatomic molecules with sub-Ångström and femtosecond spatiotemporal resolution together with relatively high sensitivity to hydrogen scattering. Here, we image the umbrella motion of an isolated ammonia molecule (NH3) following its strong field ionization. Upon ionization of a neutral ammonia molecule, the ammonia cation (NH+3) undergoes an ultrafast geometrical transformation from a pyramidal (FHNH=107°) to planar (FHNH=120°) structure in approximately 8 femtoseconds. Using LIED, we retrieve a near-planar (FHNH=117±5°) field-dressed NH+3 molecular structure 7.8-9.8 femtoseconds after ionization. Our measured field-dressed NH+3 structure is in excellent agreement with our calculated equilibrium field dressed structure using quantum chemical ab initio calculations.J.B. and group acknowledge financial support from the European Research Council for ERC Advanced Grant “TRANSFORMER” (788218), ERC Proof of Concept Grant “miniX” (840010), FET-OPEN “PETACom” (829153), FET-OPEN “OPTOlogic” (899794), Laserlab- Europe (EU-H2020 654148), MINECO for Plan Nacional FIS2017-89536-P; AGAUR for 2017 SGR 1639, MINECO for “Severo Ochoa” (SEV- 2015-0522), Fundació Cellex Barcelona, CERCA Programme / Generalitat de Catalunya, and the Alexander von Humboldt Foundation for the Friedrich Wilhelm Bessel Prize. J.B., K.A. and R.Moszynski. acknowledge the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314. J.B and B.B. acknowledge Severo Ochoa” (SEV- 2015-0522). J.B. and A.S. acknowledge funding from the Marie Sklodowska-Curie grant agreement No. 641272. C.D.L is supported in part by Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy under Grant No. DE-FG02-86ER13491. J.S. and S.G. highly acknowledges support from the European Research Council (ERC) for the ERC Consolidator Grant QUEM-CHEM (772676). The authors thank Alejandro Saenz for helpful discussions.Peer ReviewedPostprint (author's final draft

キノロン系抗菌剤 Ofloxacinにより誘発されたイヌ関節症の臨床病理学的研究

Veranda as one of the main elements of spatial hierarchy in the traditional Iranian architecture is responsible for providing visual and thermal comfort and energy saving, in the interior and to some extent exterior besides enhancing both the privacy and accessibility as a transition space all around the building. In the Solar Decathlon China 2013 (SDC 2013) house of Team Iran, the roof of veranda has been designed to be a functional part of the above goals. It is composed of several reflector pieces gathered in each veranda frame forming a traditional Iranian pattern. In the southern veranda roof, the reflector pieces are able to rotate on a daily basis, based on the amount of interior light intensity and optimal function of the water wall located in the southern facade. Through the current article this particular veranda design and its detailed mechanisms are thoroughly discussed. Lighting simulations have been performed for the interior of the house, with and without the veranda, in addition to covering different states through the day during distinct seasonal conditions for five specified geometrical layouts in the former case. Meanwhile, a data reduction procedure has been applied and validated by the obtained data in order to get an overall numerical interpretation of each case. The results confirm that the original width between the pattern elements in the traditional layout forms the optimum configuration and the rotation mechanism in the southern veranda roof further enhances the interior visual comfort

Imaging an Isolated Water Molecule using a Single Electron Wave Packet

Observing changes in molecular structure requires atomic-scale Ångstrom and femtosecond spatio-temporal resolution. We use the Fourier transform (FT) variant of laser-induced electron diffraction (LIED), FT-LIED, to directly retrieve the molecular structure of H2O+ with picometer and femtosecond resolution without a priori knowledge of the molecular structure nor the use of retrieval algorithms or ab initio calculations. We identify a symmetrically stretched H2O+ field-dressed structure that is most likely in the ground electronic state. We subsequently study the nuclear response of an isolated water molecule to an external laser field at four different field strengths. We show that upon increasing the laser field strength from 2.5 to 3.8 V/Å, the O-H bond is further stretched and the molecule slightly bends. The observed ultrafast structural changes lead to an increase in the dipole moment of water and, in turn, a stronger dipole interaction between the nuclear framework of the molecule and the intense laser field. Our results provide important insights into the coupling of the nuclear framework to a laser field as the molecular geometry of H2O+ is altered in the presence of an external field

Imaging the Renner-Teller effect using laser-induced electron diffraction

Structural information on electronically excited neutral molecules can be indirectly retrieved, largely through pump-probe and rotational spectroscopy measurements with the aid of calculations. Here, we demonstrate the direct structural retrieval of neutral carbonyl disulfide (CS$_2$) in the B$^1$B$_2$ excited electronic state using laser-induced electron diffraction (LIED). We unambiguously identify the ultrafast symmetric stretching and bending of the field-dressed neutral CS$_2$ molecule with combined picometer and attosecond resolution using intrapulse pump-probe excitation and measurement. We invoke the Renner-Teller effect to populate the B$^1$B$_2$ excited state in neutral CS$_2$, leading to bending and stretching of the molecule. Our results demonstrate the sensitivity of LIED in retrieving the geometric structure of CS$_2$, which is known to appear as a two-center scatterer

Imaging an isolated water molecule with an attosecond electron wave packet

We use laser-induced electron diffraction (LIED) to self-image the molecular structure of an isolated water molecular ion using its own retuning attosecond electron wave packet (EWP). Using LIED’s sub-femtosecond and picometre spatio-temporal resolution imaging capabilities, we observe the symmetric stretching of the O-H and H-H internuclear distances with increasing laser field strength.Postprint (published version

Ultrafast imaging of the Renner-Teller effect in a field-dressed molecule

We present experimental results of linear-to-bent transition of field-dressed molecules, mediated by Renner-Teller effect. Using the state-of-the-art laser-induced electron diffraction (LIED) technique, we image a bent and symmetrically stretched carbon disulfide (CS2) molecule populating an excited electronic state under the influence of strong laser field. Our findings are well-supported by ab initio quantum mechanical calculations.Peer ReviewedPostprint (published version

Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser

In pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene (C6H3F2I) molecules performed at the FLASH FEL that takes advantage of recent upgrades of the FLASH timing and synchronization system to obtain high-quality data that are not limited by the FEL arrival-time jitter. We discuss in detail the necessary data analysis steps and describe the origin of the time-dependent effects in the yields and kinetic energies of the fragment ions that we observe in the experiment