Two-Photon Absorption and Multiphoton Excited Fluorescence of Acetamide-Chalcone Derivatives: The Role of Dimethylamine Group on the Nonlinear Optical and Photophysical Properties.

This work studied the effect of different electron-withdrawing and electron-donating groups on the linear and nonlinear optical properties of acetamide-chalcone derivatives. The results showed that the addition of the dimethylamine group led to a large fluorescence emission (71% of fluorescence quantum yield in DMSO solution) that can be triggered by two and three-photon excitations, which is essential for biological applications. Furthermore, dimethylamine also red-shifts the lower energy state by approximately 90 nm, increasing the two-photon absorption cross-section of the lower energy band by more than 100% compared with the other studied compounds. All compounds presented two-electronic states observed through one and two-photon absorption spectroscopy and confirmed by Quantum Chemistry Calculations (QCCs). QCC results were also used to model the experimental two-photon absorption cross-sectional spectrum by the Sum-Over-States (SOS) approach, revealing a dependence between the coupling of the ground state with the first excited state and the transition dipole moment between these states.

Frequency-resolved microscopic second-order hyperpolarizability of azochromophores: a study on nonlinear all-optical switching applications.

Azochromophores present interesting optical properties for application in all-optical switches (AOSs), such as ultrafast photoisomerization and considerable nonlinear optical response. However, determining the frequency-resolved microscopic second-order hyperpolarizability (real and imaginary parts) related to the pure electronic effects of molecules in solution is a challenging task. In this context, we have used femtosecond-laser induced nonlinear ellipse rotation (NER) measurements to obtain the electronic nonlinear refraction (n2(ω)) and two-photon absorption spectra (α2PA(ω)) of four azochromophores dissolved in methanol and acetone. The measurements ranging from ∼600 up to ∼1300 nm were performed in Disperse Red 1 (DR1), Disperse Red 13 (DR13), Disperse Red 19 (DR19), and Disperse Orange 3 (DO3). Because we carried the solution in a silica cuvette and used a short focal length, we were able to measure the solution's nonlinearities with high precision, as the silica from the cuvette walls worked as a suitable reference medium. Consequently, we precisely determined n2(ω), α2PA(ω), and the second-order hyperpolarizability (γ(ω)) for all molecules and explained the different magnitudes based on the push-pull character. Furthermore, the solvation effect due to the change from methanol to acetone solvent on the n2(ω), α2PA(ω), and γ(ω) is also reported. The results were elucidated using the sum-over-states (SOS) approach within the few-energy-level model and the results were obtained via quantum-chemical calculations using the cubic response function formalism within the density functional theory framework. Finally, we used these results to determine the frequency-resolved figure-of-merit for all-optical switching applications. Our results suggest that chromophores have the potential for applications in AOS based on Fabry-Perot filters.

Heart failure as an adverse effect of infliximab for Crohn's disease: A case report and review of the literature.

BACKGROUND: Anti-tumor necrosis factor agents were the first biologic therapy approved for the management of Crohn's disease (CD). Heart failure (HF) is a rare but potential adverse effect of these medications. The objective of this report is to describe a patient with CD who developed HF after the use of infliximab. CASE SUMMARY: A 50-year-old woman with a history of hypertension and diabetes presented with abdominal pain, diarrhea, and weight loss. Colonoscopy and enterotomography showed ulcerations, areas of stenosis and dilation in the terminal ileum, and thickening of the intestinal wall. The patient underwent ileocolectomy and the surgical specimen confirmed the diagnosis of stenosing CD. The patient started infliximab and azathioprine treatment to prevent post-surgical recurrence. At 6 mo after initiating infliximab therapy, the patient complained of dyspnea, orthopnea, and paroxysmal nocturnal dyspnea that gradually worsened. Echocardiography revealed biventricular dysfunction, moderate cardiac insufficiency, an ejection fraction of 36%, and moderate pericardial effusion, consistent with HF. The cardiac disease was considered an infliximab adverse effect and the drug was discontinued. The patient received treatment with diuretics for HF and showed improvement of symptoms and cardiac function. Currently, the patient is using anti-interleukin for CD and is asymptomatic. CONCLUSION: This reported case supports the need to investigate risk factors for HF in inflammatory bowel disease patients and to consider the risk-benefit of introducing infliximab therapy in such patients presenting with HF risk factors.

Small Intestinal Hemangioma: A Case Report.

BACKGROUND Hemangiomas are benign vascular neoplasms that originate from fast-growing embryonic mesodermal tissue and have a proliferation of endothelial cells, which manifest themselves in different forms, locations, and dimensions. Owing to its rarity and similarity of symptoms with other chronic bowel diseases, intestinal hemangioma is a differential diagnosis to be considered in patients presenting with symptoms such as abdominal pain and anemia. CASE REPORT A 46-year-old woman with a history of diffuse abdominal pain and abdominal distension for 20 years presented with a worsening of symptoms in the past year. She denied weight loss or changes in bowel habits or stool appearance. Laboratory investigations showed microcytic hypochromic anemia. Colonoscopy results were normal. A contrast-enhanced abdominal computed tomography scan showed focal and concentric thickening of the small intestine, measuring 8.3 cm, and associated with calcifications, intestinal dilation, mesenteric lymph node enlargement, and vascular dilatation and consistent with infectious granulomatous diseases such as intestinal tuberculosis, carcinoid tumor, Crohn's disease, and lymphoma. The tuberculin skin test resulted in a strong 25-mm reaction. We suspected intestinal tuberculosis or expansive injury, and the patient underwent exploratory laparotomy with visualization of a 4- to 5-cm bluish/blackish vegetating lesion located 220 cm from the Treitz angle. The anatomopathological study showed cavernous hemangioma of the small intestine, measuring 2.6×1.0 cm. The patient recovered well and remained asymptomatic. CONCLUSIONS Although rare, intestinal hemangioma should be on the list of differential diagnoses for chronic intestinal diseases, especially if there is anemia due to coexisting iron deficiency.

Intramolecular Cooperative and Anti-Cooperative Effect on the Two-Photon Absorption Cross Section in Triphenylamine Derivatives.

The intramolecular cooperative effect in branched molecules is a consequence of the interaction and extent of electronic coupling among the different axes of charge transfer. Such an effect is the key to obtain remarkable nonlinear optical response in molecular systems. Here we show that triphenylamine derivative molecules containing only two branches present the strongest electronic interaction between them at the excited state, generating exponential enhancement of the 2PA cross section. The primary factor for such behavior was ascribed to the substantial extent and interaction of the π-electron delocalization promoted by the strong electron-donating and acceptor antisymmetrical groups present in each branch. However, for the three-branch molecules we observed an anticooperative effect, i.e., the 2PA cross section decreases as compared to the one-branch structure as we normalized the signal by the effective π-electron number in each molecule.