Search

Many research efforts are focused toward significant improvements of polymeric solar cells efficiency, energy harvesting range, time, and environmental stability. Particular attention is given to hybrid organic/inorganic composites constituted of polymer/lead chalcogenides (PbS and PbSe) nanocrystals (NCs) to extend the spectral sensitivity of cells to near-infrared wavelengths. In this work we report the synthesis and characterization of PbS nanocrystals with absorption edge at 984 nm. The nanocrystals have a cubic crystal structure and size of about 2 nmas found by X-ray diffraction analysis. They were combined with poly(3-hexylthiophene) (P3HT) polymer to obtain P3HT:PbS blends with different PbS loadings. A postdeposition ligand exchange on PbS NCs by 1,2-ethanedithiol (EDT) allowed a better interaction between polymer and nanocrystals as showed by fluorescence measurements. The P3HT:PbS blends were deposited and treated by a layer by layer spin coating process and used as active layer in solar cells having structure glass/ITO/PEDOT:PSS/blend/Al. The major result obtained for this hybrid system is an increase of PCE by about two orders of magnitude with respect to analogous reported cells where a post-deposition ligand exchange was performed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this work, FETs are used as a research tool to study charge carrier mobilities in PbS nanocrystals (NCs) thin-films employed as semiconducting layer in bottom-gate bottom-contact (BGBC) field-effect transistors (FETs). The as-synthesised NCs are surrounded by long alkyl chain ligands which act as electrical insulators. Therefore, a ligand exchange process with shorter molecules is necessary to enhance the free charges generation and transport. We used two different ligands: 1,2 ethandithiol (EDT) and 1,2,3,4-tetrabutylammonium iodide (TBAI) and studied the charge mobility of PbS NCs comparing the electrical characteristics of FETs made by exchanged NCs. We analysed also the contemporary presence of both exchanged nanocrystals on the device. All the transistors showed p-type transport behaviour, enhanced by an annealing process at 100 °C for 10 min. After this, only the TBAI-treated NCs devices showed a n-type transport, resulting in an ambipolar behaviour. Inkjet printing deposition techniques was also successfully used to deposit PbS-(TBAI) NCs and ambipolar devices were obtained. In addition, for printed devices it was found that it is possible to modulate the charge transport properties by applying surface treatment to the substrate with a pentafluorothiophenol (PFTP). Indeed in this case, the p-type transport was suppressed while n-type behaviour was induced. © 2015 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim.

Blends of conductive polymer poly(3-hexylthiophene) (P3HT) and size controlled MoS2 nanotubes (NTs) were prepared focusing on procedures which do not alter the electrical and optical properties of nanotubes, i.e., without surfactants. After disassembly of as-grown hedgehog-like self-assemblies of the MoS2 NTs, relatively homogeneous dispersions of the NTs in P3HT were prepared. Thin films of these blends were prepared via spin coating. The NTs were found efficiently wetted by the P3HT and nearly completely immersed in the films. The surface structure was composed of pure P3HT lamellae. Photoluminescence spectra taken on P3HT/MoS2 NT thin films revealed a quenching effect, which depends on the concentration of NTs. Results of optical microscopy and spectroscopy investigations, scanning tunnelling microscopy and scanning electron microscopy studies are shown. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tungsten disulfide (WS2) nanotubes are used to prepare polymer nanocomposites, similarly to other metal dichalcogenide materials, to improve lubricating and/or mechanical properties. In order to explore the possibility to extend these advantages to conductive polymers we realized new nanocomposites of WS2 nanotubes and polyfluorene conjugated polymer (WS 2/PFO). The nanocomposites were prepared from solution processing at several nanotubes concentrations. The morphological and structural analyses by SEM and XRD proved that the density of nanotubes within the polymer increased according to the preparation conditions. The successful incorporation of WS 2 nanotubes was also evidenced by UV-Vis absorbance spectroscopy. The WS2/PFO nanocomposites were tested in light emitting devices at relatively big load of nanotubes realizing a new class of devices with promising improved mechanical and thermal properties without affecting substantially the device optoelectronic performances. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sourcerecord Id Scopus 40682 Abstract Aim. Endovenous laser treatment (EVLT) appears to be an useful alternative to conventional surgery in treatment of advanced varicose veins, in ambulatory regimen too. Methods. Over a 1-year period, otherwise unselected consecutive series of 52 GSVs in 40 patients (36 females, 4 males; age 39 to 63 yrs.) with varicose veins due to GSV incompetence (up to 1,2 cm in diameter at the saphenofemoral junction) were included. After selective spinal anaesthesia, laser energy (diode laser 980 nm) was administered endovenously. A laser fiber (δ 600 μ; length 2 m) was inserted from malleolus to sapheno-femoral junction. Laser energy (12-15 J/sec. - 40-80 J/cm 2) was administered either continuously, during constant backpull of the laser fibre, or in a pulsed fashion (on time 1-2 sec.; off time 1 sec.; withdrawing the fibre 1 cm every 1 sec.). Results. Absence of flow on colour Doppler imaging was considered sign of successful occlusion of the GSV. Patients were evaluated clinically and with duplex US at 1 week, 1 month, six months, and 1 year. Successful occlusion of the GSV was noted in 44/52 GSVs (84,6%) after initial treatment. Twenty four of thirty limbs, followed for six months, remained closed (80,0%), and, among these, no recurrence was detected in limbs (20) followed-up at 1 year. Conclusion. Clinical efficacy of EVLT seems to be demonstrated by early, mid and long-term results, from many groups, comparable or superior to those reported for the other treatments of GSV reflux, including surgery.

We report the early and mid-term results in the treatment of the great saphenous vein (GSV) by endovenous laser diode 980 nm. Despite a rapid spread of the technique, not all is known about the laser-tissue interaction in endovenous laser treatment (EVLT). We developed this study to assess the safety and efficacy of EVLT, a recent percutaneous technique for permanent occlusion of the incompetent GSV.

This study was conducted to obtain more detailed histopathological data on the application of EVLT in patients with an incompetent GSV. In ten surgical procedures, at the end of EVLT, a segment of terminal tract of the GSV (2-4 cm length) was collected in order to be microscopically analysed. Histopathological data were developed to clarify the injury of EVLT on the inner vessel wall, in order to improve clinical treatment efficacy and safety.

Sourcerecord Id Scopus 2375 Endovenous laser treatment for great saphenous vein appears to be an useful alternative to conventional surgery in treatment of advanced varicose veins, in ambulatory regimen too. A recurring problem in laser applications is estimating the thermal response of target tissues to laser irradiation. This typically involves using an optical model to determine the distribution of absorbed laser energy and then using a thermal model to establish the temperature during and after laser irradiation. In the present work we have calculated the power irradiation of the walls of vessel, hypothesising a diameter of the vein cm 0.8-1.5, a length cm 70-90 and haematic flow equal zero. We used Lambert-Beer law, assuming a cylindrical symmetry in the incoming intensity irradiation (I-o), as in the case in the TEM00 mode. Omitting details we calculated a power irradiation, depending on the vein diameter, of 10-20 watt using diode laser 980 nm. This study offers high importance data in order to foresee the effective transfer of thermal damage to the vein wall through absorption of laser energy.http://apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=1&SID=Q1i@gpCm9b3mdEmO@n6&page=2&doc=14

After an extensive review of the literature regarding maxillary sinus lift procedures, the authors report the results of a retrospective study carried out by the Institute of Oral and Maxillofacial Surgery at the Second University of Naples.A group of 9 patients aged between 18 and 50 years old, including two females, were enrolled in this study. At the preliminary evaluation, the sites to be analysed showed a bone height between the residual crest and the sinusal membrane not exceeding 8 mm. All patients responded positively to specific preimplantation requisites. Commercially pure titanium fixtures were used as well as demineralised freeze-dried bovine bone and autologous bone graft from the retromolar region.All patients were followed for at least 15 months and no clinical check-ups were missed during that time. No implant was lost and no cases of spire exposure were reported. Postoperative vertical bone resorption was within normal values.Summers technique and its variations with bone grafts of various kinds represents a valid aid for edentulous maxillary rehabilitation with scarce osseous resources in the postero-superior sectors. It offers a number of advantages compared to the traditional technique using an invasive lateral approach and is more acceptable to patients. However, in spite of this positive experience, the follow-up in the literature still appears to be too short. The authors, are therefore cautious in expressing their absolute preference for Summers technique and stress the need to wait for further long-term results.

Background: Scarce information is available on the duration of the protective effect of COVID-19 vaccination against the risk of SARS-CoV-2 infection and its severe clinical consequences. We investigated the effect of time since vaccine completion on the SARS-CoV-2 infection and its severe forms. Methods: In this retrospective observational analysis using the vaccination campaign integrated platform of the Italian region of Lombardy, 5 351 085 individuals aged 12 years or older who received complete vaccination from Jan 17 to July 31, 2021, were followed up from 14 days after vaccine completion until Oct 20, 2021. Changes over time in outcome rates (ie, SARS-CoV-2 infection and severe illness among vaccinated individuals) were analysed with age-period-cohort models. Trends in vaccine effectiveness (ie, outcomes comparison in vaccinated and unvaccinated individuals) were also measured. Findings: Overall, 14 140 infections and 2450 severe illnesses were documented, corresponding to incidence rates of 6·7 (95% CI 6·6–6·8) and 1·2 (1·1–1·2) cases per 10 000 person-months, respectively. From the first to the ninth month since vaccine completion, rates increased from 4·6 to 10·2 infections, and from 1·0 to 1·7 severe illnesses every 10 000 person-months. These figures correspond to relative reduction of vaccine effectiveness of 54·9% (95% CI 48·3–60·6) for infection and of 40·0% (16·2–57·0) for severe illness. The increasing infection rate was greater for individuals aged 60 years or older who received adenovirus-vectored vaccines (from 4·0 to 23·5 cases every 10 000 person-months). The increasing severe illness rates were similar for individuals receiving mRNA-based vaccines (from 1·1 to 1·5 every 10 000 person-months) and adenovirus-vectored vaccines (from 0·5 to 0·9 every 10 000 person-months). Interpretation: Although the risk of infection after vaccination, and even more of severe illness, remains low, the gradual increase in clinical outcomes related to SARS-CoV-2 infection suggests that the booster campaign should be accelerated and that social and individual protection measures against COVID-19 spread should not be abandoned. Funding: None.

We aimed to identify individual features associated with increased risk of post-vaccine SARS-CoV-2 infection and severe COVID-19 illness. We performed a nested case–control study based on 5,350,295 citizens from Lombardy, Italy, aged ≥ 12 years who received a complete anti-COVID-19 vaccination from 17 January 2021 to 31 July 2021, and followed from 14 days after vaccine completion to 11 November 2021. Overall, 17,996 infections and 3023 severe illness cases occurred. For each case, controls were 1:1 (infection cases) or 1:10 (severe illness cases) matched for municipality of residence and date of vaccination completion. The association between selected predictors (sex, age, previous occurrence of SARS-CoV-2 infection, type of vaccine received, number of previous contacts with the Regional Health Service (RHS), and the presence of 59 diseases) and outcomes was assessed by using multivariable conditional logistic regression models. Sex, age, previous SARS-CoV-2 infection, type of vaccine and number of contacts with the RHS were associated with the risk of infection and severe illness. Moreover, higher odds of infection and severe illness were significantly associated with 14 and 34 diseases, respectively, among those investigated. These results can be helpful to clinicians and policy makers for prioritizing interventions.

Background. Limited evidence exists on the balance between the benefits and harms of the COVID-19 vaccines. The aim of this study is to compare the benefits and safety of mRNA-based (Pfizer-BioNTech and Moderna) and adenovirus-vectored (Oxford-AstraZeneca) vaccines in subpopulations defined by age and sex. Methods. All citizens who are newly vaccinated from 27 December 2020 to 3 May 2021 are matched to unvaccinated controls according to age, sex, and vaccination date. Study outcomes include the events that are expected to be avoided by vaccination (i.e., hospitalization and death from COVID-19) and those that might be increased after vaccine inoculation (i.e., venous thromboembolism). The incidence rate ratios (IRR) of vaccinated and unvaccinated citizens are separately estimated within strata of sex, age category and vaccine type. When suitable, number needed to treat (NNT) and number needed to harm (NNH) are calculated to evaluate the balance between the benefits and harm of vaccines within each sex and age category. Results. In total, 2,351,883 citizens are included because they received at least one dose of vaccine (755,557 Oxford-AstraZeneca and 1,596,326 Pfizer/Moderna). A reduced incidence of COVID-19-related outcomes is observed with a lowered incidence rate ranging from 55% to 89% and NNT values ranging from 296 to 3977. Evidence of an augmented incidence of harm-related outcomes is observed only for women aged

Abstract Background The evolution of SARS-CoV-2 has led to the emergence of several new variants, and few data are available on the impact of vaccination on SARS-CoV-2 variants. We aimed to assess the association between natural (previous infection) and induced (partial or complete vaccination) exposure to SARS-CoV-2 and the onset of new infection supported by the delta variant, and of comparing it with that supported by alpha. Methods We performed a test-negative case-control study, by linking population-based registries of confirmed diagnoses of infection with SARS-CoV-2, vaccinations against Covid-19 and healthcare utilization databases of the Italian Lombardy Region. Four hundred ninety-six persons who between 27 December 2020 and 16 July 2021 had an infection by the delta variant were 1:1 matched with citizens affected by alphavariant and 1:10 matched with persons who had a negative molecular test, according to gender, age and date of molecular ascertainment. We used a conditional logistic regression for estimating relative risk reduction of either variants associated with natural and/or induced immunization and corresponding 95% confidence interval (CI). Results Previous infection was associated with 91% (95% CI 85% to 95%) reduced relative risk of reinfection, without evidence of significant differences between delta and alpha cases (p=0.547). Significant lower vaccinal protection against delta than alpha variant infection was observed with reduced relative risk associated with partial vaccination respectively of 29% (7% to 45%), and 62% (48% to 71%) (p=0.001), and with complete vaccination respectively of 75% (66% to 82%) and 90% (85% to 94%) (p=0.003). Conclusions Lower protection towards infections caused by the delta variant with respect to alpha variant was noticed, even after the completion of the vaccination cycle. This finding would support efforts to maximize both vaccine uptake with two doses and fulfilment with individual protection measures, especially as the delta variant is rampant worldwide presently.