22 research outputs found

    Fabrication and photophysical studies of CdTe quantum-dots dispersed in SiO2 sonogel optical-glasses

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    The catalyst-free sonogel route has been implemented to fabricate highly pure SiO2 glasses as host materials for CdTe quantum dot nanocrystals synthesized in aqueous solution. Developed CdTe-based inorganic–inorganic hybrid composites exhibited rigid bulk structures with controllable geometrical shapes and dopant concentrations, allowing the control of the optical properties in the solid-state confinement. Comprehensive linear and nonlinear photophysical characterizations were performed according to UV–vis absorbance, Raman and photoluminescent spectroscopies; the linear refractive indices of highly/lowly CdTe-doped samples were also estimated according to the Brewster angle technique. Since the hybrid glasses are amorphous in nature, the cubic nonlinear optical activity of these composites has been tested via the Z-Scan technique. Results show that the CdTe quantum dots were homogeneously embedded within the SiO2-sonogel matrix with only small guest–host molecular interactions and preserving their strong photoluminescent properties; thus providing advanced solid-state heterostructured nanocomposite materials suitable for current technological photonic applications

    Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

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    PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

    Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

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    PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

    Use of anticoagulants and antiplatelet agents in stable outpatients with coronary artery disease and atrial fibrillation. International CLARIFY registry

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    Synthesis and characterization of poly(ethylene glycol) diacrylate copolymers containing azobenzene groups prepared by frontal polymerization

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    A novel polymer matrix containing amino–nitro substituted azobenzene groups was obtained by frontal polymerization. (E)-2-(Ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl methacrylate (MDR-1) was copolymerized with poly(ethylene glycol) diacrylate (PEGDA) using this easy and fast polymerization technique. The effect of the amount of the incorporated azomonomer into the polymer matrix was studied in detail and correlated to front velocity, maximum temperature, initiator concentration, and monomer conversion. The obtained materials were characterized by infrared spectroscopy (Fourier transform infrared), and their thermal properties were studied by thermogravimetric analysis and differential scanning calorimetry. Moreover, the optical properties of the polymers were studied by absorption spectroscopy in the UV–Vis region. Absorption spectra of the copolymers exhibit a significant blue shift of the absorption bands with respect to the azo-monomer, due to the presence of H-aggregates. Cubic nonlinear optical (NLO) characterizations of the PEGDA/MDR-1 copolymers were performed according to the Z-Scan technique. It has been proven that samples with higher MDR-1 content (0.75 mol %) exhibited outstandingly high NLOactivity with negative NLO-refractive coefficients in the promising range of n2 = -8.057 X 10-4 esu

    Synthesis and optical characterization of photoactive poly(2-phenoxyethyl acrylate) copolymers containing azobenzene units, prepared by frontal polymerization using novel ionic liquids as initiators

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    2-Phenoxyethyl acrylate (2-PEA) was polymerized alone and in the presence of an azobenzene comonomer derived from Disperse Red-1, N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline (MDR-1), by using the frontal polymerization technique. Two novel ionic liquids, recently synthesized by us, were used as initiators: tetrabutylphosphonium persulfate (TBPPS) and trihexyltetradecylphosphonium persulfate (TETDPPS). Even if their concentrations were smaller than those found when benzoyl peroxide and terbutylperoxy neodecanoate were used, these compounds gave rise to stable propagating polymerization fronts characterized by relatively low maximum temperatures and good velocities. Moreover, at variance to these latter, TBPPS and TETDPPS prevent bubble formation, thus allowing the use of the obtained materials in optical applications. The obtained polymers were characterized by infrared spectroscopy (FTIR), their thermal properties were determined by differential scanning calorimetry, and their optical properties were studied by absorption spectroscopy in the UV–vis region. Finally, the nonlinear optical (NLO) properties of the 2-PEA/MDR-1 copolymers obtained with TBPPS and TETDPPS were performed according to the Z-Scan technique with prepared film samples. It has been proven that samples with higher MDR-1 content (0.05 mol %) exhibited outstanding cubic NLO activity with negative NLO refractive coefficients around n2 = −1.7 × 10−3 esu

    Preparation and optical characterization of two photoactive poly(bisphenol A ethoxylate diacrylate) copolymers containing designed amino-nitro-substituted azobenzene units, obtained via classical and frontal polymerization, using novel ionic liquids as initiators

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    The frontal polymerization (FP) of bisphenol A ethoxylate diacrylate (BPAEDA) was carried with and without the presence of two different azobenzene comonomers by means of an external heating source. The first azomonomer (MDR-1) is a derivative of disperse red-1, N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline, whereas the second (E)-2-(4-((4-nitrophenyl)diazenyl)phenyl)-5,8,11-trioxa-2-azatridecan-13-yl methacrylate (4PEGMAN) comes from the azo-dye Nmethyl- N-{4-[(E)-(4-nitrophenyl)diazenyl]phenyl}-N-(11-hydroxy-3,6,9-trioxaundecas-1-yl) amine. In this work, an ionic liquid trihexyltetradecylphosphonium persulfate was used as initiator. This compound produced stable propagating polymerization fronts with good velocities and moderate maximum temperature values. Moreover, this initiator prevented bubble formation and was found to be the most efficient when it was used in lower amounts with respect to other initiators, such as benzoyl peroxide, 2,20-azobisisobutyronitrile, aliquat persulfateÂź, and tetrabutylphosphonium persulfate. The thermal properties of the obtained polymers and copolymers were determined by thermogravimetric analysis and differential scanning calorimetry. The nonlinear optical (NLO) characterizations of the developed BPAEDA/MDR-1 and BPAEDA/4PEGMAN copolymers were performed according to the Z-Scan technique in film samples prepared by classical polymerization. It has been proven that samples with higher 4PEGMAN content (0.26 mol %) exhibited outstanding cubic NLO-activity with positive NLO-refractive coefficients in the promising range of n2 = +3.2 x 10-4 esu
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