Intrinsic Point Defects in Silica for Fiber Optics Applications.

Due to its unique properties, amorphous silicon dioxide (a-SiO2) or silica is a key material in many technological fields, such as high-power laser systems, telecommunications, and fiber optics. In recent years, major efforts have been made in the development of highly transparent glasses, able to resist ionizing and non-ionizing radiation. However the widespread application of many silica-based technologies, particularly silica optical fibers, is still limited by the radiation-induced formation of point defects, which decrease their durability and transmission efficiency. Although this aspect has been widely investigated, the optical properties of certain defects and the correlation between their formation dynamics and the structure of the pristine glass remains an open issue. For this reason, it is of paramount importance to gain a deeper understanding of the structure-reactivity relationship in a-SiO2 for the prediction of the optical properties of a glass based on its manufacturing parameters, and the realization of more efficient devices. To this end, we here report on the state of the most important intrinsic point defects in pure silica, with a particular emphasis on their main spectroscopic features, their atomic structure, and the effects of their presence on the transmission properties of optical fibers.

The free energy landscape of the oncogene protein E7 of human papillomavirus type 16 reveals a complex interplay between ordered and disordered regions.

When present, structural disorder makes it very challenging to characterise the conformational properties of proteins. This is particularly the case of proteins, such as the oncogene protein E7 of human papillomavirus type 16, which contain both ordered and disordered domains, and that can populate monomeric and oligomeric states under physiological conditions. Nuclear magnetic resonance (NMR) spectroscopy is emerging as a powerful method to study these complex systems, most notably in combination with molecular dynamics simulations. Here we use NMR chemical shifts and residual dipolar couplings as structural restraints in replica-averaged molecular dynamics simulations to determine the free energy landscape of E7. This landscape reveals a complex interplay between a folded but highly dynamical C-terminal domain and a disordered N-terminal domain that forms transient secondary and tertiary structures, as well as an equilibrium between a high-populated (98%) dimeric state and a low-populated (2%) monomeric state. These results provide compelling evidence of the complex conformational heterogeneity associated with the behaviour and interactions of this disordered protein associated with disease.

Smartphone-based immunosensor for CA125 detection.

In this work, we report the design, the development and the characterization of the analytical performances of a colorimetric smartphone-based immunosensor for the detection of cancer antigen 125 (CA125). The immunosensor was based on a sandwich strategy in which the primary antibody was immobilized by spotting onto the 3D nitrocellulose membrane. The immunospots were subsequently incubated with CA125 solutions, followed by the affinity reaction with a secondary antibody labeled with gold nanoparticles (AuNPs). The antibody-AuNPs captured onto immunospots induced the silver deposition from a silver enhancer solution leading to the formation of gold-silver nanoparticles of different grey color spots depending on CA125 concentration. The 8 megapixels smartphone camera was integrated in a home-made dark box and used as transducer of color image acquisition and data handling. The pixel intensity of the captured images was determined by an image processing algorithm. The experimental parameters involved in each step of the immunosensor design were studied and optimized, obtaining a limit of detection of 30U/mL CA125. The selectivity of the immunoassay was proven against different concentration solutions of Vascular Endothelial Growth Factor (VEGF) antigen as an unspecific protein when a blank signal was obtained for all tested solutions. Finally, preliminary experiments in human serum samples spiked with CA125 protein were also performed. Therefore, the proposed system could represent a powerful point-of-care tool for the next generation technology for detecting and monitoring cancer biomarkers at early stages by taking advantage of nowadays gadgets with enhanced features such as smartphones.

Acceptance of noninvasive computed tomography coronary angiography: for a patient-friendly medicine.

PURPOSE: This study was done to evaluate the psychological state and anxiety of patients undergoing computed tomography coronary angiography (CTCA), and assess their acceptance and satisfaction compared to invasive conventional coronary angiography (CCA). MATERIALS AND METHODS: A total of 442 consecutive patients (282 male; mean age 57.7 ± 9.5 years) who underwent CTCA for suspected or known coronary artery disease were evaluated with the Endler Multimodality Anxiety Scales (EMAS) before and after the scan, and a questionnaire administered after the scan. Among the 442 patients, 181 had a history of CCA. Two radiologists assessed the image quality of CTCA. RESULTS: Anxiety was more intense prior to the scan (EMAS score 51.7 vs. 46.7, p < 0.01) and in patients with a history of CCA (EMAS score 55.5 vs. 49.1, p < 0.01). Women presented more intense anxiety (EMAS score 59.5 vs. 47.3, p < 0.01), higher mean heart rate (63.5 ± 7.6 vs. 60.7 ± 7.3 beats per minute, p < 0.01) and a lower image quality than men (p < 0.0001). CTCA proved to be more acceptable than CCA because of accurate preparation, lower concern prior to the examination, negligible pain, higher comfort, and greater overall satisfaction (p < 0.0001). CONCLUSIONS: Computed tomography coronary angiography is a patient-friendly imaging method because of the minimal perceived discomfort. Anxiety may affect CTCA image quality in women.

The self-locating catheter: clinical experience and follow-up.

BACKGROUND: The self-locating catheter invented by Nicola Di Paolo has been used increasingly in Italy and elsewhere since 1994, with about a thousand patients currently implanted every year. Twelve grams of tungsten inserted into the tip of the conventional Tenckhoff catheter during extrusion does not significantly change its form, but suffices to keep the tip firmly in the Douglas cavity. OBJECTIVE: The aim of the present study was to confirm our preliminary results in a large population of peritoneal dialysis patients. SETTING: 16 Italian nephrology departments. RESULTS: In addition to confirming the validity of the new catheter, the present results show that patients with the new catheter have fewer episodes of peritonitis, tunnel infection, cuff extrusion, catheter malfunction, obstruction, and leakage. CONCLUSION: The present multicenter control study confirms preliminary results and demonstrates that complications of peritoneal dialysis, such as cuff extrusion, infection, peritonitis, early leakage, and obstruction, are statistically less frequent in patients with self-locating catheters than in patients with classic Tenckhoff catheters.