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J Bresien, A Hinz, A Schulz, A Villinger
Since the heavy biradicals [E(μ-NTer)]2 (E = Sb, Bi) are only of fleeting existence in solution, they were generated in situ and trapped by [2 + 2] addition reactions utilizing alkynes such as tolan (Ph-C[triple bond, length as m-dash]C-Ph). The structure, biradical character and bonding of [E(μ-NTer)]2 biradicals as well as their addition products are discussed on the basis of computations and experimental data.
March 1, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
S S Skurikhin, I N Milkevich, I A Bolotin, V A Odintsov, A I Buynyakova, E B Zhogoleva, Yu V Suvorova
AIM: To assess the diagnostic significance and safety of vacuum-assisted resection in patients with focal breast cancer BIRADS category 3 and 4. MATERIAL AND METHODS: The procedure was performed in 50 women aged 22 to 51 years (35.1±2.6 years). RESULTS: There were no any complications immediately after vacuum resection. Tissue of the neoplasm was removed in full in all patients. Benign and malignant tumors were observed in 94 and 6% cases respectively...
2018: Khirurgiia
Thierry Dubroca, Adam N Smith, Kevin J Pike, Stuart Froud, Richard Wylde, Bianca Trociewitz, Johannes McKay, Frederic Mentink-Vigier, Johan van Tol, Sungsool Wi, William Brey, Joanna R Long, Lucio Frydman, Stephen Hill
Nuclear magnetic resonance (NMR) is an intrinsically insensitive technique, with Boltzmann distributions of nuclear spin states on the order of parts per million in conventional magnetic fields. To overcome this limitation, dynamic nuclear polarization (DNP) can be used to gain up to three orders of magnitude in signal enhancement, which can decrease experimental time by up to six orders of magnitude. In DNP experiments, nuclear spin polarization is enhanced by transferring the relatively larger electron polarization to NMR active nuclei via microwave irradiation...
January 31, 2018: Journal of Magnetic Resonance
Emmanuel Amoah Boafo, Kwabena Darko, Bright Aryeh Afriyie, Richard Tia, Evans Adei
The mechanistic aspects of cycloaddition reactions of 1,2-cyclohexadiene with olefins and nitrones have been investigated with DFT calculations. The results show that the cycloaddition reactions of 1,2-cyclohexadiene with olefins do not go through a concerted pathway (one-step mechanism) but rather a stepwise one involving the formation of a biradical intermediate which then closes to form final cycloadduct. Electron-withdrawing substituents on the 1,2-cyclohexadiene decrease the activation barrier of the biradical-forming step but increase the barrier of the product-forming step and product stability, while electron-donating substituents on the 1,2-cyclohexadiene increase the barriers for both the biradical-forming step and the product-forming step but decrease the product stability...
February 13, 2018: Journal of Molecular Graphics & Modelling
E López, D Ascenzi, P Tosi, J M Bofill, J de Andrés, M Albertí, J M Lucas, A Aguilar
Cyclopropyl cyanide and other simple nitriles detected in Titan's atmosphere could be precursors leading to the formation of organic macromolecules in the atmosphere of Saturn's largest satellite. Proposing a thermodynamically possible mechanism that explains their formation and supports experimental results represents a difficult challenge. Experiments done in the Atomic and Molecular Physics Laboratory at the University of Trento (AMPL) have studied the ion-molecule reaction between cyclopropyl cyanide and its protonated form, with reaction products being characterized by mass spectrometry...
February 12, 2018: Physical Chemistry Chemical Physics: PCCP
Mark C Murphy, Louise Coffey, Ailbhe C O'Neill, Cecily Quinn, Ruth Prichard, Sorcha McNally
AIMS AND OBJECTIVES: The aim of this study was to determine if the synthetic C view acquired at digital breast tomosynthesis (DBT) would give adequate information to confirm a malignancy and could obviate the need to review all the tomosynthesis image data set. METHODS: All patients with biopsy-proven breast cancer recalled from screening mammograms between May and September 2016 were included for review. For each patient, the screening 2D mammogram, the synthetic C view, and the DBT images were reviewed by three breast radiologists and each assigned a BIRADS code...
February 9, 2018: Irish Journal of Medical Science
Marc-Antoine Sani, Pierre-Alexandre Martin, Ruhamah Yunis, Fangfang Chen, Maria Forsyth, Michael Deschamps, Luke A O'Dell
Dynamic nuclear polarisation (DNP) enhanced solid-state NMR spectroscopy has been used to study an ionic liquid salt solution (N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide, C3mpyrFSI, containing 1.0 m lithium bis(fluorosulfonyl)imide, 6LiFSI) in its glassy state at a temperature of 92 K. The incorporation of a biradical to enable DNP signal enhancement allowed the proximities of the lithium to the individual carbon sites on the pyrrolidinium cation to be probed using a 13C-6Li REDOR pulse sequence...
February 8, 2018: Journal of Physical Chemistry Letters
Hongdao Li, Juan Sun, Meng Yang, Zan Sun, Jinkui Tang, Yue Ma, Licun Li
Functionalized nitronyl nitroxide biradical ligands incorporating pyridine groups hold CoII and LnIII ions together, creating biradical-based 3d-4f tetranuclear complexes [Ln2Co2(hfac)10(NITPhPybis)2] [LnIII = Gd (1), Tb (2), Dy (3), and Ho (4); NITPhPybis = 5-(4-pyridyl)-1,3-bis(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene; hfac = hexafluoroacetylacetonate]. These complexes have a centrosymmetric cyclic molecular structure in which two biradicals perform as tetradentate ligands to bind two CoII and two LnIII ions, resulting in a rare octaspin system...
February 8, 2018: Inorganic Chemistry
Ouissam El Bakouri, Marc Garcia-Borràs, Rosa M Girón, Salvatore Filippone, Nazario Martín, Miquel Solà
Controlling the regioselectivity in the exohedral functionalization of fullerenes and endohedral metallofullerenes is essential to produce specific desired fullerene derivatives. In this work, using density functional theory (DFT) calculations, we show that the regioselectivity of the Diels-Alder (DA) cycloaddition of cyclopentadiene to 2S+1C60 changes from the usual [6,6] addition in the singlet ground state to the [5,6] attack in high spin states of C60. Changes in the aromaticity of the five- and six-membered rings when going from singlet to high spin C60 provide a rationale to understand this regioselectivity change...
February 8, 2018: Physical Chemistry Chemical Physics: PCCP
Aida Abou-Zamzam, Scott Somers, Cherie Cora, Seyed Pairawan, Sharon Lum
Percutaneous needle biopsy (PNB) of the breast is commonly used for diagnosis of breast pathology, but has been less studied in young women. We sought to determine the effectiveness and necessity of PNB in patients younger than 35 years of age. The charts of sequential patients <35 years who underwent PNB between February 2013 and May 2016 were reviewed; 181 PNB were performed in 127 patients. Median age was 30 years (13-34). Indications for PNB were Breast Imaging Reporting and Data System (BIRADS) ≥4 in 137 (75...
October 1, 2017: American Surgeon
Julia E McGuinness, William Ueng, Meghna S Trivedi, Hae Seung Yi, Raven David, Alejandro Vanegas, Jennifer Vargas, Rossy Sandoval, Rita Kukafka, Katherine D Crew
BACKGROUND: Potential harms of screening mammography include false positive results, such as recall breast imaging or biopsies. METHODS: We recruited women undergoing screening mammography at Columbia University Medical Center in New York, NY. They completed a questionnaire on breast cancer risk factors and permitted access to their medical records. Breast cancer risk status was determined using the Gail model and a family history screener. High-risk was defined as a 5-year invasive breast cancer risk of 1...
January 30, 2018: Cancer Epidemiology, Biomarkers & Prevention
Rodger Rausch, David Schmidt, David Bialas, Ivo Krummenacher, Holger Braunschweig, Frank Würthner
The first isoindigo (bi)radicals were obtained by proton coupled oxidation of their 4-hydroxyaryl substituted precursors. Optical and magnetic spectroscopic studies revealed a singlet open-shell biradicaloid electronic ground state for the bisphenoxyl-isoindigo (<s2> = 1.20) with a small singlet-triplet energy gap of 0.065 eV and a large biradical character of y = 0.79 that was corroborated by temperature-dependent EPR spectroscopy and quantum chemical calculations. The concept of kinetic blocking of the radical centers and delocalization of spin density into the electron-withdrawing chromophore core of isoindigo offers an entry into a new class of exceptionally stable open-shell functional materials based on organic colorants...
January 26, 2018: Chemistry: a European Journal
Ewa Łukasiewicz, Agnieszka Ziemiecka, Wiesław Jakubowski, Jelena Vojinovic, Magdalena Bogucevska, Katarzyna Dobruch-Sobczak
Aim: The aim of the study was to review two techniques that can be used to verify focal lesions in the breasts: fine-needle aspiration biopsy and core-needle biopsy. Material and methods: Fifty-five articles (original papers and reviews), half of them published within the past 5 years, were included in the analysis. The authors also took their own experience into account. Results: Pre-operative assessment of focal lesions in the breasts is crucial in the planning of further therapeutic management...
December 2017: Journal of Ultrasonography
Dhrubajyoti Mondal, Mithun Chandra Majee, Sanchita Kundu, Max Mörtel, Ghulam Abbas, Akira Endo, Marat M Khusniyarov, Muktimoy Chaudhury
Bis-bidentate ligand H4LB featuring two o-amidophenol noninnocent units was used to synthesize novel binuclear complexes [(LR)MIII(•LB•)MIII(LR)](ClO4)2, M = Fe (1) and Co (2, 3), with HLR (R = CH3, Cl) being the facially coordinating tetradentate coligands. Upon the synthesis, the fully reduced amidophenolate form of the ligand (LB)4- becomes oxidized, resulting in the formation of a rare example of a biradical (•LB•)2- bridge connecting two metal ions, as supported by X-ray crystallography. The electronic structures of the complexes have been probed by Mössbauer spectroscopy, magnetic susceptibility measurements, and electron paramagnetic resonance (EPR) spectroscopy...
January 24, 2018: Inorganic Chemistry
David James Coughtrie, Robin Giereth, Daniel Kats, Hans-Joachim Werner, Andreas Köhn
Internally contracted multireference coupled cluster (icMRCC) theory is embedded within multireference perturbation theory (MRPT) to calculate energy differences in large strongly correlated systems. The embedding scheme is based on partitioning the orbital spaces of a complete active space self consistent field (CASSCF) wave function, with the truncated virtual space constructed by transforming selected projected atomic orbitals (PAOs). MRPT is applied to the environment using a subtractive embedding approach, that also allows for multilayer embedding...
January 18, 2018: Journal of Chemical Theory and Computation
Izumi Yonekawa, Katsuya Mutoh, Yoichi Kobayashi, Jiro Abe
The development of two-photon induced photochromic compounds is important for advanced photoresponsive materials. The utilization of the long-lived transient states or species for two-photon absorption is one of the efficient strategies to realize the advanced photochemical behavior beyond a one-photon photochemical reaction. We have synthesized bi-photochromic compounds composed of two photochromic phenoxyl-imidazolyl radical complex units. The biphotochromic compounds generate two biradical units when the two photochromic units absorb photons with a stepwise manner...
January 16, 2018: Photochemical & Photobiological Sciences
Ashley I Huppe, Anita K Mehta, Rachel F Brem
Molecular breast imaging (MBI), also called breast-specific gamma imaging (BSGI), has been an integral component of our breast imaging practice for over a decade. Unlike mammography and ultrasound that are based on anatomy, MBI is a physiologic approach to breast cancer detection. MBI detects additional foci of occult breast cancer in 9.0% of women with newly diagnosed breast cancer, has a high sensitivity for detecting high-risk lesions, and detects 98% of invasive breast cancer and 91.0% of ductal carcinoma in situ...
February 2018: Seminars in Ultrasound, CT, and MR
Clemens Rauer, Juan J Nogueira, Philipp Marquetand, Leticia González
Abstract: Cyclobutane thymine dimerization is the most prominent DNA photoinduced damage. While the ultrafast mechanism that proceeds in the singlet manifold is nowadays well established, the triplet-state pathway is not completely understood. Here we report the underlying mechanism of the photosensitized dimerization process in the triplet state. Quantum chemical calculations, combined with wavefunction analysis, and nonadiabatic molecular dynamics simulations demonstrate that this is a stepwise reaction, traversing a long-lived triplet biradical intermediate, which is characterized as a Frenkel exciton with very small charge-transfer character...
2018: Monatshefte Für Chemie
Tchin Darré, Mazamaesso Tchaou, Koué Folligan, Abdoulatif Amadou, Bidamin N'Timon, Lantam Sonhaye, Abdoul-Samadou Aboubakari, Koffi Amégbor, Koffi Akpadza, Gado Napo Koura
Breast cancer in young female patients represents a public health problem in developing countries. The objectives of the study were to study the epidemiological and histological characteristics of breast cancer in female patients under 35 years of age. This was a retrospective analytical study of a series of 158 cases of breast cancer in female patients under 35 years of age, conducted at the University Teaching Hospital of Lomé between 2000 and 2015. A total of 158 cases were collected, representing 36.2% (436) of all breast cancer cases...
December 2017: Molecular and Clinical Oncology
Jean-Francois Morin, Maude Desroches
Three new and stable diradical-dications based on the 4,10-dibromoanthanthrone have been synthesized and characterized. In their dicationic state, the amines show a biradical character in the ground state. Their magnetic properties have been investigated by NMR and EPR. The dicationic salts shows strong and broad optical absorption in the near-infrared region. The main driving force to obtain a ground state biradical is the high steric hindrance that prevent planarization of the diphenylamines with the anthanthrone aromatic core...
December 23, 2017: Chemistry: a European Journal
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