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https://www.readbyqxmd.com/read/28214227/automated-breast-density-computation-in-digital-mammography-and-digital-breast-tomosynthesis-influence-on-mean-glandular-dose-and-birads-density-categorization
#1
Maria Castillo-García, Margarita Chevalier, Julia Garayoa, Alejandro Rodriguez-Ruiz, Diego García-Pinto, Julio Valverde
RATIONALE AND OBJECTIVES: The study aimed to compare the breast density estimates from two algorithms on full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) and to analyze the clinical implications. MATERIALS AND METHODS: We selected 561 FFDM and DBT examinations from patients without breast pathologies. Two versions of a commercial software (Quantra 2D and Quantra 3D) calculated the volumetric breast density automatically in FFDM and DBT, respectively...
February 14, 2017: Academic Radiology
https://www.readbyqxmd.com/read/28207235/explorations-of-the-indenofluorenes-and-expanded-quinoidal-analogues
#2
Conerd K Frederickson, Bradley D Rose, Michael M Haley
Highly conjugated hydrocarbons have attracted interest for use as active materials in electronic devices such as organic field effect transistors (OFET) and organic photovoltaics (OPV). In this Account, we review our progress in synthesizing and studying a new class of small molecules for potential use as organic semiconductors. The idea originated from prior research on octadehydrodibenz[12]annulene, as the system can undergo double transannular cyclization to yield the indeno[1,2-b]fluorene skeleton. Subsequent functionalization afforded the first stable, well-characterized indeno[1,2-b]fluorene derivatives, albeit in minute quantities (tens of milligrams)...
February 16, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28198127/a-stable-saddle-shaped-polycyclic-hydrocarbon-with-an-open-shell-singlet-ground-state
#3
Ji Ma, Junzhi Liu, Martin Baumgarten, Yubin Fu, Yuan-Zhi Tan, Karl Sebastian Schellhammer, Frank Ortmann, Gianaurelio Cuniberti, Hartmut Komber, Reinhard Berger, Klaus Müllen, Xinliang Feng
Diindeno-fused bischrysene, a new diindeno-based polycyclic hydrocarbon (PH), was synthesized and characterized. It was elucidated in detailed experimental and theoretical studies that this cyclopenta-fused PH possesses an open-shell singlet biradical structure in the ground state and exhibits high stability under ambient conditions (t1/2 =39 days). The crystal structure unambiguously shows a novel saddle-shaped π-conjugated carbon skeleton due to the steric hindrance of the central cove-edged bischrysene unit...
February 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28194976/reversible-photoisomerization-among-triplet-amino-naphthylnitrene-triplet-diimine-biradical-and-indazole-matrix-isolation-ir-spectra-of-8-amino-1-naphthylnitrene-1-8-naphthalenediimine-and-1-2-dihydrobenz-cd-indazole
#4
Takuya Okamura, Nobuyuki Akai, Munetaka Nakata
Reaction mechanisms of nitrene, one of the most famous biradicals, have been frequently studied, and many spectral data have been obtained so far. In the present study, the experimental IR spectra of triplet 8-amino-1-naphthylnitrene ((3)ANN), a triplet diimine biradical 1,8-dihydro-1,8-naphthalenediimine ((3)DND), and 1,2-dihydrobenz[cd]indazole (DBI), which are produced in the UV photolysis of 1,8-diaminonaphthalene in an Ar matrix and identified by a combination method of IR spectroscopy and DFT quantum chemical calculations, are first reported...
February 17, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28191929/stop-frame-filming-and-discovery-of-reactions-at-the-single-molecule-level-by-transmission-electron-microscopy
#5
Thomas W Chamberlain, Johannes Biskupek, Stephen T Skowron, Alexander V Markevich, Simon Kurasch, Oliver Reimer, Kate Walker, Graham A Rance, Xinliang Feng, Klaus Müllen, Andrey Turchanin, Maria A Lebedeva, Alexander Majouga, Valentine Georgievich Nenajdenko, Ute Kaiser, Elena Besley, Andrei N Khlobystov
We report an approach - named chemTEM - to follow chemical transformations at the single-molecule level with the electron beam of a transmission electron microscope (TEM) applied as both a tuneable source of energy and a sub-Angstrom imaging probe. Deposited on graphene, disk-shaped perchlorocoronene molecules are precluded from intermolecular interactions. This allows monomolecular transformations to be studied at the single-molecule level in real time and reveals chlorine elimination and reactive aryne formation as a key initial stage of multi-step reactions initiated by the 80 keV e-beam...
February 13, 2017: ACS Nano
https://www.readbyqxmd.com/read/28140501/bis-aminoaryl-carbon-bridged-oligo-phenylenevinylene-s-expand-the-limits-of-electronic-couplings
#6
Paula Mayorga Burrezo, Nai-Ti Lin, Koji Nakabayashi, Shin-Ichi Ohkoshi, Eva M Calzado, Pedro G Boj, María A Díaz García, Carlos Franco, Concepciò Rovira, Jaume Veciana, Michael Moos, Christoph Lambert, Juan T López Navarrete, Hayato Tsuji, Eiichi Nakamura, Juan Casado
Carbon-bridged bis(aminoaryl) oligo(para-phenylenevinylene)s have been prepared and their optical, electrochemical, and structural properties analyzed. Their radical cations are class III and class II mixed-valence systems, depending on the molecular size, and they show electronic couplings which are among the largest for the self-exchange reaction of purely organic molecules. In their dication states, the antiferromagnetic coupling is progressively tuned with size from quinoidal closed-shell to open-shell biradicals...
January 31, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28129144/geometry-based-pectoral-muscle-segmentation-from-mlo-mammogram-views
#7
Saeid Asgari Taghanaki, Yonghuai Liu, Brandon Miles, Ghassan Hamarneh
Computer aided diagnosis systems (CADx) play a major role in the early diagnosis of breast cancer. Extracting the breast region precisely from a mammogram is an essential component of CADx for mammography. The appearance of the pectoral muscle on medio-lateral oblique (MLO) views increases the false positive rate in CADx. Therefore, the pectoral muscle should be identified and removed from the breast region in an MLO image before further analysis. None of the previous pectoral muscle segmentation methods address all breast types based on the breast imaging-reporting and data system (BIRADS) tissue density classes...
January 24, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28099013/dynamic-nuclear-polarization-signal-enhancement-with-high-affinity-biradical-tags
#8
Rivkah Rogawski, Ivan V Sergeyev, Yongjun Li, M Francesca Ottaviani, Virginia Cornish, Ann E McDermott
Dynamic nuclear polarization is an emerging technique for sensitizing solid-state NMR experiments by transferring polarization from electrons to nuclei. Stable biradicals, the polarization source for the cross effect mechanism, are typically codissolved at millimolar concentrations with proteins of interest. Here we describe the high-affinity biradical tag TMP-T, created by covalently linking trimethoprim, a nanomolar affinity ligand of dihydrofolate reductase (DHFR), to the biradical polarizing agent TOTAPOL...
February 6, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28098267/a-tailored-multi-frequency-epr-approach-to-accurately-determine-the-magnetic-resonance-parameters-of-dynamic-nuclear-polarization-agents-application-to-amupol
#9
P Gast, D Mance, E Zurlo, K L Ivanov, M Baldus, M Huber
To understand the dynamic nuclear polarization (DNP) enhancements of biradical polarizing agents, the magnetic resonance parameters need to be known. We describe a tailored EPR approach to accurately determine electron spin-spin coupling parameters using a combination of standard (9 GHz), high (95 GHz) and ultra-high (275 GHz) frequency EPR. Comparing liquid- and frozen-solution continuous-wave EPR spectra provides accurate anisotropic dipolar interaction D and isotropic exchange interaction J parameters of the DNP biradical AMUPol...
February 1, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28094939/unimolecular-decomposition-mechanism-of-1-2-dioxetanedione-concerted-or-biradical-that-is-the-question
#10
Pooria Farahani, Wilhelm J Baader
Determination of the ground- and excited-state unimolecular decomposition mechanisms of 1,2-dioxetanedione gives a level of insight into bimolecular decomposition reactions of this kind for which some experimental results are reported. Although a few studies have put some effort to describe a biradical mechanism of this decomposition, there is still no systematic study that proves an existence of a biradical character. In the present study, state-of-the-art high-level multistate multiconfigurational reference second-order perturbation theory calculations are performed to describe the reaction mechanism of 1,2-dioxetanedione in detail...
February 1, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28067435/mr-imaging-findings-in-molecular-subtypes-of-breast-cancer-according-to-birads-system
#11
Lidia Navarro Vilar, Salvador Pascual Alandete Germán, Rosana Medina García, Esther Blanc García, Natalia Camarasa Lillo, José Vilar Samper
To evaluate magnetic resonance imaging (MRI) findings, according to Breast Imaging-Reporting and Data System (BI-RADS), and to relate them with molecular subtypes of breast cancer. The MRI findings were reviewed retrospectively in 201 women diagnosed of invasive breast cancer confirmed by surgery and were compared with the molecular subtypes. Following the BI-RADS, MRI findings included disease type, size, enhancement, morphology and contrast kinetics. In mass-like lesion types were studied shape, margin and enhancement, and in nonmass-like lesion types, distribution modifiers and internal enhancement...
January 9, 2017: Breast Journal
https://www.readbyqxmd.com/read/28067367/reply-to-the-comment-on-trans-1-2-disiloxybenzocyclobutene-an-adequate-partner-for-the-auto-oxidation-epr-spin-trapping-and-theoretical-studies-by-h-g-korth-p-mulder-and-t-paul-phys-chem-chem-phys-2017-19-c6cp04187f
#12
Yannick Carissan, Paola Nava, Béatrice Tuccio, Laurent Commeiras, Jean-Luc Parrain
The proposal and the comments made by Korth et al. on a biradical intermediate along the isomerization path of the reaction of trans-1,2-tert-butyldimethyldisilyloxybenzocyclobutene 1 with dioxygen are unsuitable in our case. The mechanism scenario that we proposed is in agreement with our experimental observations. Moreover, new calculations were able to give an answer to the crucial question, "is the biradical an intermediate or a transition state?" together with the localization of the two radicals. This full article is a response to the "Comment on "trans-1,2-Disiloxybenzocyclobutene, an adequate partner for the auto-oxidation: EPR/spin trapping and theoretical studies" by J...
January 9, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28057293/fibroepithelial-breast-lesions-diagnosed-by-core-needle-biopsy-demonstrate-a-moderate-rate-of-upstaging-to-phyllodes-tumors
#13
Gabriel Marcil, Stephanie Wong, Nora Trabulsi, Alexandra Allard-Coutu, Armen Parsyan, Atilla Omeroglu, Gulbeyaz Atinel, Benoit Mesurolle, Sarkis Meterissian
BACKGROUND: Fibroepithelial lesions of the breast (FEL) are atypical lesions diagnosed on core-needle biopsy. The purpose of this study was to determine the rate at which FELs are upstaged to phyllodes tumor on excision, and to examine the clinical and radiological factors that may be predictive of upstaging. METHODS: A retrospective review from the medical records of patients diagnosed with FEL on CNB at a single institution between 2010 and 2015 was performed...
December 27, 2016: American Journal of Surgery
https://www.readbyqxmd.com/read/28044952/diagnostic-value-of-frozen-section-in-patients-with-non-palpable-breast-lesions
#14
Hacı Hasan Abuoglu, Emre Günay, Oğuzhan Sunamak, M Rafet Yiğitbaşı
AIM: We analyzed wire-marking, frozen section (FS) and surgical approach in malignancy-suspicious non-palpable lesions detected on mammography (MG) and ultrasonography (US) as breast mass, microcalcifications and distorsions. Material and Methods: A hundred patients in whom wiremarking and frozen section analysis was performed because of non-palpable, malignancy-suspected breast lesions at General Surgery Department, Goztepe Training and Research Hospital, Istanbul were analyzed retrospectively...
November 2016: Chirurgia
https://www.readbyqxmd.com/read/28000810/comment-on-trans-1-2-disiloxybenzocyclobutene-an-adequate-partner-for-the-auto-oxidation-epr-spin-trapping-and-theoretical-studies-by-j-drujon-et-al-phys-chem-chem-phys-2014-16-7513
#15
Hans-Gert Korth, Peter Mulder, Thomas Paul
Despite the claim of the contrary, (i) the facile formation of a ring-opened cyclic peroxide from reaction of a 1,2-disubstituted benzocyclobutene with molecular oxygen has been reported before, and (ii) the analysis of the mechanistic steps of this process is incomplete, as only the symmetry-allowed conrotatory ring-opening of the benzocyclobutene has been considered. The probable involvement of biradical intermediates/biradicaloid transition states in a formally symmetry-forbidden reaction sequence has not been taken into account...
December 21, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27933881/neutral-aminyl-radicals-derived-from-azoimidazolium-dyes
#16
Léonard Y M Eymann, Alexander G Tskhovrebov, Andrzej Sienkiewicz, José L Bila, Ivica Živković, Henrik M Rønnow, Matthew D Wodrich, Laurent Vannay, Clémence Corminboeuf, Philip Pattison, Euro Solari, Rosario Scopelliti, Kay Severin
The synthesis and characterization of a new class of neutral aminyl radicals is reported. Monoradicals were obtained by reduction of azoimidazolium dyes with potassium. Structural, spectroscopic, and computational data suggest that the spin density is centered on one of the nitrogen atoms of the former azo group. The reduction of a dimeric dye with an octamethylbiphenylene bridge between the azo groups resulted in the formation of a biradical with largely independent unpaired electrons. Both the monoradicals and the biradical were found to display high stability in solution as well as in the solid state...
November 23, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27906486/the-fractional-occupation-number-weighted-density-as-a-versatile-analysis-tool-for-molecules-with-a-complicated-electronic-structure
#17
Christoph Alexander Bauer, Andreas Hansen, Stefan Grimme
The fractional occupation number weighted density (FOD) analysis is explored as a general theoretical diagnostic for complicated electronic structures. Its main feature is to provide robustly and fast the information where 'hot' (strongly correlated and chemically active) electrons are localized in a molecule. We demonstrate its usage in four different prototypical applications: (i) As a new and fast measure for the biradical character of polycyclic aromatic hydrocarbons, (ii) for the selection of active orbital spaces in multiconfigurational or complete active space self consistent field (MCSCF/CASSCF) treatments, (iii) as a possibility to consistently describe molecular energy landscapes in regions with varying biradical character as exemplified by partial double bond torsions, and (iv) as a powerful visualization method for static electron correlation effects in large biomolecules in connection with an efficient semi-empirical tight-binding molecular orbital scheme...
December 1, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27812560/orientation-order-and-rotation-mobility-of-nitroxide-biradicals-determined-by-quantitative-simulation-of-epr-spectra
#18
Alexey V Bogdanov, Andrey Kh Vorobiev
The problem of quantitative numerical simulation of electron paramagnetic resonance (EPR) spectra of biradical probes in both isotropic and aligned media was solved for the first time. The models suitable for the description of the spectra of the probes, both in the rigid limit and in the presence of rotational motions, were developed and successfully applied to model systems. The simulation of EPR spectra allows obtaining the following information about the molecular structure and dynamics: the values of orientation order parameters, the type of rotation mobility and its quantitative characteristics, and the sign and value of the spin exchange constant of the biradical...
November 16, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27771952/using-molecular-architecture-to-control-the-reactivity-of-a-triplet-vinylnitrene
#19
Sujan K Sarkar, Onyinye Osisioma, William L Karney, Manabu Abe, Anna D Gudmundsdottir
Photolysis of 3-azido-1-indenone (1) with a light-emitting diode (LED, λ = 405 nm) or mercury arc lamp (Pyrex) resulted in the formation of heterodimer 3 in excellent yield, through dimerization of triplet vinylnitrene (3)2. At ambient temperature, vinylnitrene (3)2 (λmax at 340 and 480 nm) was detected directly with laser flash photolysis of vinyl azide 1. The vinylnitrene intermediate was also characterized directly with IR and ESR spectroscopy in cryogenic matrices. The ESR spectrum of vinylnitrene (3)2 yielded a zero-field splitting parameter |D/hc| of 0...
November 16, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27747007/cell-block-samples-from-endobronchial-ultrasound-transbronchial-needle-aspiration-provide-sufficient-material-for-ancillary-testing-in-lung-cancer-a-quaternary-referral-centre-experience
#20
Emily Hopkins, David Moffat, Ian Parkinson, Peter Robinson, Hubertus Jersmann, Brendan Dougherty, Mohammed I Birader, Kate Francis, Phan Nguyen
BACKGROUND: Rapid on site examination (ROSE) is encouraged at endobronchial ultrasound transbronchial needles aspiration (EBUS-TBNA) to improve diagnostic yield. Due to new therapeutic options in lung cancer, it is not sufficient to merely distinguish between non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC). Immunohistochemistry (IHC) distinction is now standard practice, as well as additional molecular testing where clinically indicated. We investigated the diagnostic yield of on-site smears vs...
September 2016: Journal of Thoracic Disease
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