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1.
Proc Natl Acad Sci U S A ; 119(12): e2118573119, 2022 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-35290119

RESUMO

Although catenanes comprising two ring-shaped components can be made in large quantities by templation, the preparation of three-dimensional (3D) catenanes with cage-shaped components is still in its infancy. Here, we report the design and syntheses of two 3D catenanes by a sequence of SN2 reactions in one pot. The resulting triply mechanically interlocked molecules were fully characterized in both the solution and solid states. Mechanistic studies have revealed that a suit[3]ane, which contains a threefold symmetric cage component as the suit and a tribromide component as the body, is formed at elevated temperatures. This suit[3]ane was identified as the key reactive intermediate for the selective formation of the two 3D catenanes which do not represent thermodynamic minima. We foresee a future in which this particular synthetic strategy guides the rational design and production of mechanically interlocked molecules under kinetic control.


Assuntos
Catenanos , Rotaxanos , Catenanos/química , Cinética , Rotaxanos/química
2.
J Am Chem Soc ; 146(29): 20158-20167, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-38978232

RESUMO

The development of architecturally unique molecular nanocarbons by bottom-up organic synthesis is essential for accessing functional organic materials awaiting technological developments in fields such as energy, electronics, and biomedicine. Herein, we describe the design and synthesis of a triptycene-based three-dimensional (3D) nanocarbon, GFN-1, with geometrical flexibility on account of its three peripheral π-panels being capable of interconverting between two curved conformations. An effective through-space electronic communication among the three π-panels of GFN-1 has been observed in its monocationic radical form, which exhibits an extensively delocalized spin density over the entire 3D π-system as revealed by electron paramagnetic resonance and UV-vis-NIR spectroscopies. The flexible 3D molecular architecture of GFN-1, along with its densely packed superstructures in the presence of fullerenes, is revealed by microcrystal electron diffraction and single-crystal X-ray diffraction, which establish the coexistence of both propeller and tweezer conformations in the solid state. GFN-1 exhibits strong binding affinities for fullerenes, leading to host-guest complexes that display rapid photoinduced electron transfer within a picosecond. The outcomes of this research could pave the way for the utilization of shape and electronically complementary nanocarbons in the construction of functional coassemblies.

3.
J Phys Chem A ; 125(3): 825-834, 2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33449684

RESUMO

Quantum coherence effects on charge transfer and spin dynamics in a system having two degenerate electron acceptors are studied using a zinc 5,10,15-tri(n-pentyl)-20-phenylporphyrin (ZnP) electron donor covalently linked to either one or two naphthalene-1,8:4,5-bis(dicarboximide) (NDI) electron acceptors using an anthracene (An) spacer, ZnP-An-NDI (1) and ZnP-An-NDI2 (2), respectively. Following photoexcitation of 1 and 2 in toluene at 295 K, femtosecond transient absorption spectroscopy shows that the electron transfer (ET) rate constant for 2 is about three times larger than that of 1, which can be accounted for by the statistical nature of incoherent ET as well as the electron couplings for the charge separation reactions. In contrast, the rate constant for charge recombination (CR) of 1 is about 25% faster than that of 2. Using femtosecond transient infrared spectroscopy and theoretical analysis, we find that the electron on NDI2•- in 2 localizes onto one of the two NDIs prior to CR, thus precluding electronically coherent CR from NDI2•-. Conversely, CR in both 1 and 2 is spin coherent as indicated by the observation of a resonance in the 3*ZnP yield following CR as a function of applied magnetic field, giving spin-spin exchange interaction energies of 2J = 210 and 236 mT, respectively, where the line width of the resonance for 2 is greater than 1. These data show that while CR is a spin-coherent process, incoherent hopping of the electron between the two NDIs in 2, consistent with the lack of delocalization noted above, results in greater spin decoherence in 2 relative to 1.

4.
Skeletal Radiol ; 49(1): 171-175, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31642973

RESUMO

Peer-reviewed abstracts presented at the 2019 Society of Skeletal Radiology (SSR) Annual Meeting were reviewed following oral presentation. Topics felt to be of potential interest to musculoskeletal (MSK) investigators and practicing clinicians are highlighted in this compilation and analysis of the meeting. New concepts regarding MSK imaging and intervention, MSK protocols and techniques, and quality improvement are included. ePoster highlights are also presented.


Assuntos
Doenças Ósseas/diagnóstico por imagem , Esqueleto/diagnóstico por imagem , Humanos
5.
Skeletal Radiol ; 49(Suppl 1): 1-33, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32488336

RESUMO

Members of the International Skeletal Society compiled a glossary of terms for musculoskeletal radiology. The authors also represent national radiology or pathology societies in Asia, Australia, Europe, and the USA. We provide brief descriptions of musculoskeletal structures, disease processes, and syndromes and address their imaging features. Given the abundance of musculoskeletal disorders and derangements, we chose to omit most terms relating to neoplasm, spine, intervention, and pediatrics. Consensus agreement was obtained from 19 musculoskeletal radiology societies worldwide.


Assuntos
Diagnóstico por Imagem/métodos , Doenças Musculoesqueléticas/diagnóstico por imagem , Terminologia como Assunto , Humanos , Internacionalidade , Sistema Musculoesquelético/diagnóstico por imagem , Sociedades Médicas
6.
Semin Musculoskelet Radiol ; 23(3): 289-303, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31163503

RESUMO

Osteoarthritis (OA) of the hip is caused by degeneration of articular cartilage and the underlying bone and can be divided into two types: primary (associated with advancing age) and secondary (subsequent to fractures, avascular necrosis, infection, developmental dysplasia, and femoroacetabular impingement). Radiography remains the first-line imaging modality for diagnosing and monitoring OA, due to its accessibility, low cost, and ease of interpretation. Kellgren-Lawrence and Tönnis classification systems are radiographic OA grading systems used primarily in research, and they reflect the degree of joint space narrowing, sclerosis, cysts, deformity of the femoral head and acetabulum, and osteophytes. Unenhanced computed tomography (CT) provides detailed visualization of the hip joint segments that may be difficult to appreciate on radiographs, such as the inferoposterior and posterolateral hip joint. CT arthrography, magnetic resonance imaging (MRI), and magnetic resonance arthrography with two-dimensional reconstructions can delineate labral abnormalities, cartilage lesions, and other intra-articular hip pathology. T2 and T2* mapping, delayed gadolinium-enhanced MRI of cartilage, T1rho, ultra-short echo time, and zero echo time are investigative MR techniques with promising evaluation of hip OA.


Assuntos
Artrografia/métodos , Articulação do Quadril/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Osteoartrite do Quadril/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Cartilagem Articular/diagnóstico por imagem , Humanos , Radiologistas
7.
AJR Am J Roentgenol ; 211(3): 506-518, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29927329

RESUMO

OBJECTIVE: The purpose of this article is to assist radiologists in developing an organized, systematic approach to imaging interpretation in the care of patients who have been surgically treated for sarcoma. CONCLUSION: Postoperative imaging interpretation of sarcoma can be complex and requires an organized, systematic approach that includes review of the patient's clinical and surgical history and pretreatment images to gain context for differentiating recurrence from time-dependent posttreatment changes.


Assuntos
Sarcoma/diagnóstico por imagem , Sarcoma/cirurgia , Neoplasias de Tecidos Moles/diagnóstico por imagem , Neoplasias de Tecidos Moles/cirurgia , Humanos , Período Pós-Operatório , Radiografia
8.
Skeletal Radiol ; 47(2): 155-159, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28939978

RESUMO

Peer-reviewed abstracts presented at the 2017 Society of Skeletal Radiology (SSR) Annual Meeting were reviewed following oral presentation. Topics felt to be of potential interest to musculoskeletal (MSK) investigators and practicing clinicians are highlighted in this compilation and analysis of the meeting. New concepts regarding MSK imaging and intervention, MSK protocols and techniques and quality improvement are included. ePoster highlights are also presented.


Assuntos
Doenças Ósseas/diagnóstico por imagem , Osso e Ossos/diagnóstico por imagem , Congressos como Assunto , Humanos , New York , Sociedades Médicas
9.
Skeletal Radiol ; 47(3): 381-387, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29260259

RESUMO

INTRODUCTION: Research productivity is one of the few quintessential gauges that North American academic radiology departments implement to determine career progression. The rationale of this study is to quantify the relationship of gender, research productivity, and academic advancements in the musculoskeletal (MSK) radiology to account for emerging trends in workforce diversity. METHODS: Radiology residency programs enlisted in the Fellowship and Residency Electronic Interactive Database (FREIDA), Canadian Resident Matching Service (CaRMS) and International Skeletal Society (ISS) were searched for academic faculty to generate the database for gender and academic profiles of MSK radiologists. Bibliometric data was collected using Elsevier's SCOPUS archives, and analyzed using Stata version 14.2. RESULTS: Among 274 MSK radiologists in North America, 190 (69.34%) were men and 84 (30.66%) were women, indicating a statistically significant difference (χ2 = 6.34; p value = 0.042). The available number of female assistant professors (n = 50) was more than half of the male assistant professors (n = 88), this ratio however, plummeted at higher academic ranks, with only one-fourth of women (n = 11) professors compared to men (n = 45). The male MSK radiologist had 1.31 times the odds of having a higher h-index, keeping all other variables constant. CONCLUSIONS: The trend of gender disparity exists in MSK radiology with significant underrepresentation of women in top tiers of academic hierarchy. Even with comparable h-indices, at the lower academic ranks, a lesser number of women are promoted relative to their male colleagues. Further studies are needed to investigate the degree of influence research productivity has, in determining academic advancement of MSK radiologists.


Assuntos
Pesquisa Biomédica , Radiologia , Centros Médicos Acadêmicos , Bibliometria , Feminino , Humanos , Masculino , América do Norte , Fatores Sexuais , Recursos Humanos
10.
J Org Chem ; 82(17): 8864-8872, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28718639

RESUMO

A systematic study of the N-substitution reactions of 3-substituted pyrazoles under basic conditions has been undertaken. Regioselective N1-alkylation, -arylation, and -heteroarylation of 3-substituted pyrazoles have been achieved using K2CO3-DMSO. The regioselectivity is justified by the DFT calculations at the B3LYP/6-31G**(d) level. A consistent steric effect on chemical shift has been observed for N-alkyl pyrazole analogues. Twenty-five X-ray crystallographic structures have been obtained to confirm the regiochemistry of the major products.

11.
Radiographics ; 36(6): 1807-1827, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27726754

RESUMO

With increasing participation and intensity of training in youth sports in the United States, the incidence of sports-related injuries is increasing, and the types of injuries are shifting. In this article, the authors review sports injuries of the lower extremity, including both acute and overuse injuries, that are common in or specific to the pediatric population. Common traumatic injuries that occur in individuals of all ages (eg, tears of the acetabular labrum and anterior cruciate ligament) are not addressed, although these occur routinely in pediatric sports. However, some injuries that occur almost exclusively in high-level athletes (eg, athletic pubalgia) are reviewed to increase awareness and understanding of these entities among pediatric radiologists who may not be familiar with them and thus may not look for them. Injuries are described according to their location (ie, hip, knee, or foot and ankle) and pathologic process (eg, apophysitis, osteochondritis dissecans). Examples of abnormalities and normal variants of the anatomy that are often misdiagnosed are provided. The injuries reviewed represent a common and growing subset of pathologic processes about which all pediatric and musculoskeletal radiologists should be knowledgeable. Understanding physeal injury is especially important because missed diagnoses can lead to premature physeal closure and osteoarthritis. ©RSNA, 2016.


Assuntos
Traumatismos em Atletas/diagnóstico por imagem , Fraturas Ósseas/diagnóstico por imagem , Aumento da Imagem/métodos , Traumatismos da Perna/diagnóstico por imagem , Osteoartrite/diagnóstico por imagem , Lesões dos Tecidos Moles/diagnóstico por imagem , Adolescente , Criança , Pré-Escolar , Diagnóstico Diferencial , Medicina Baseada em Evidências , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Posicionamento do Paciente/métodos , Ultrassonografia/métodos
12.
Radiographics ; 36(6): 1828-1848, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27726748

RESUMO

A variety of surgical procedures exist for repair of both traumatic and degenerative osseous and soft-tissue pathologic conditions involving the foot and ankle. It is necessary for the radiologist to be familiar with these surgical procedures, so as to assess structural integrity, evaluate for complicating features, and avoid diagnostic pitfalls. Adequate interpretation of postoperative changes often requires access to surgical documentation to evaluate not only the surgery itself but the expected timeline for resolution of normal postoperative changes versus progressive disease. Appropriate use of surgical language in radiology reports is another important skill set to hone and is instrumental in providing a high-quality report to the referring surgeons. The pathophysiology of a myriad of surgical complaints, beginning from the Achilles tendon and concluding at the plantar plate, are presented, as are their common appearances at computed tomography and magnetic resonance imaging. Commonly encountered entities include Achilles tendon tear, spastic equinus, nonspastic equinus, talar dome osteochondral defect, tarsal tunnel syndrome, plantar fasciitis, pes planovalgus, pes cavovarus, peroneal tendinosis, lateral ligament complex pathology, Morton neuroma, plantar plate tear, and metatarsophalangeal joint instability. Computer-generated three-dimensional models are included with many of the procedures to provide a more global view of the surgical anatomy. Correlation with intraoperative photographs is made when available. When appropriate, discussion of postoperative complications, including entities such as infection and failure of graft integration, is presented, although a comprehensive review of postoperative complications is beyond the scope of this article. Notably absent from the current review are some common foot and ankle procedures including hallux valgus and hammertoe corrections, as these are more often evaluated radiographically than with cross-sectional imaging. ©RSNA, 2016.


Assuntos
Traumatismos do Tornozelo/diagnóstico por imagem , Traumatismos do Pé/diagnóstico por imagem , Artropatias/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Complicações Pós-Operatórias/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Traumatismos do Tornozelo/cirurgia , Diagnóstico Diferencial , Medicina Baseada em Evidências , Traumatismos do Pé/cirurgia , Fraturas Ósseas/diagnóstico por imagem , Fraturas Ósseas/cirurgia , Humanos , Aumento da Imagem/métodos , Posicionamento do Paciente/métodos , Lesões dos Tecidos Moles/diagnóstico por imagem , Lesões dos Tecidos Moles/cirurgia , Resultado do Tratamento
13.
Skeletal Radiol ; 45(11): 1461-5, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27600141

RESUMO

Peer-reviewed abstracts presented at the 2016 Society of Skeletal Radiology (SSR) Annual Meeting were reviewed following oral presentation. Topics felt to be of potential interest to musculoskeletal (MSK) investigators and practicing clinicians are highlighted in this compilation and analysis of the meeting. New concepts regarding MSK imaging and intervention, MSK protocols and techniques, radiology education and quality improvement are included. ePoster highlights are also presented.


Assuntos
Pesquisa Biomédica/tendências , Diagnóstico por Imagem/tendências , Ortopedia/tendências , Radiologia/tendências , Humanos
14.
Skeletal Radiol ; 45(1): 3-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26338070

RESUMO

Peer-reviewed abstracts presented at the 2015 Society of Skeletal Radiology (SSR) 38th Annual Meeting were reviewed following oral presentation. Topics felt to be of potential interest to musculoskeletal (MSK) investigators and practicing clinicians are highlighted in this compilation and analysis of the meeting. New concepts regarding MSK imaging and intervention, MSK protocols and techniques, and quality improvement are included. ePoster highlights are also presented.


Assuntos
Doenças Ósseas/diagnóstico , Diagnóstico por Imagem/tendências , Fraturas Ósseas/diagnóstico , Artropatias/diagnóstico , Doenças Musculares/diagnóstico , Radiologia/tendências , Humanos
17.
Semin Musculoskelet Radiol ; 19(1): 67-76, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25633027

RESUMO

Significant innovations in the field of total ankle replacement surgery have occurred since the early disappointing experiences with first-generation devices. In recent years, total ankle arthroplasties are commonly placed in patients with end-stage ankle osteoarthrosis, supplanting ankle arthrodesis as the procedure of choice at some institutions. Careful clinical and preoperative radiographic evaluation is helpful to plan concomitant ligament release, ligament reconstruction, or osteotomy. Careful attention to radiographic signs of early hardware loosening or subsidence can prompt intervention while bone loss is still minimal, and computed tomography has an adjunct role in the evaluation of periprosthetic lucency and osteolysis.


Assuntos
Artroplastia de Substituição do Tornozelo , Diagnóstico por Imagem , Articulação do Tornozelo/diagnóstico por imagem , Articulação do Tornozelo/cirurgia , Humanos , Radiografia
18.
Skeletal Radiol ; 44(3): 313-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25492635

RESUMO

Peer-reviewed abstracts presented at the 2014 Society of Skeletal Radiology (SSR) annual meeting were reviewed following oral presentation. Topics felt to be of potential interest to musculoskeletal (MSK) investigators and practicing clinicians are highlighted in this compilation and analysis of the meeting. New concepts regarding MSK imaging and intervention, MSK protocols and techniques, radiology education and quality improvement are included. ePoster highlights are also presented.


Assuntos
Artrografia/tendências , Fraturas Ósseas/diagnóstico , Artropatias/diagnóstico , Imageamento por Ressonância Magnética/tendências , Ultrassonografia/tendências , Artrografia/métodos , Humanos
20.
Radiology ; 267(2): 589-95, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23401583

RESUMO

The Society of Radiologists in Ultrasound convened a panel of specialists from a variety of medical disciplines to reach a consensus about the recommended imaging evaluation of painful shoulders with clinically suspected rotator cuff disease. The panel met in Chicago, Ill, on October 18 and 19, 2011, and created this consensus statement regarding the roles of radiography, ultrasonography (US), computed tomography (CT), CT arthrography, magnetic resonance (MR) imaging, and MR arthrography. The consensus panel consisted of two co-moderators, a facilitator, a statistician and health care economist, and 10 physicians who have specialty expertise in shoulder pain evaluation and/or treatment. Of the 13 physicians on the panel, nine were radiologists who were chosen to represent a broad range of skill sets in diagnostic imaging, different practice types (private and academic), and different geographical regions of the United States. Five of the radiologists routinely performed musculoskeletal US as part of their practice and four did not. There was also one representative from each of the following clinical specialties: rheumatology, physical medicine and rehabilitation, orthopedic surgery, and nonoperative sports medicine. The goal of this conference was to construct several algorithms with which to guide the imaging evaluation of suspected rotator cuff disease in patients with a native rotator cuff, patients with a repaired rotator cuff, and patients who have undergone shoulder replacement. The panel hopes that these recommendations will lead to greater uniformity in rotator cuff imaging and more cost-effective care for patients suspected of having rotator cuff abnormality.


Assuntos
Algoritmos , Diagnóstico por Imagem , Manguito Rotador/patologia , Dor de Ombro/diagnóstico , Humanos , Dor de Ombro/patologia
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