First examples of pyran based colorants as sensitizing agents of p-Type Dye-Sensitized solar cells

Three different pyran based dyes were synthesized and tested for the first time as photosensitizers of NiO based p-type dye-sensitized solar cells (p-DSSC). The molecules feature a similar molecular structure and are based on a pyran core that is functionalized with electron acceptor groups of different strength and is symmetrically coupled to phenothiazine donor branches. Optical properties of the dyes are deeply influenced by the nature of the electron-acceptor group, so that the overall absorption of the three dyes covers the most of the visible spectrum. The properties of devices based on the NiO electrodes sensitized with the investigated dyes were evaluated under simulated solar radiation: the larger short circuit current density exceeded 1mA/cm2 and power conversion efficiency as high as 0.04% could be recorded. The performances of the fabricated p-DSSC have been compared to a reference cell sensitized with P1, a high level benchmark, which afforded a photoelectrochemical activity similar to the best example of our pyran sensitized devices (1.19 mA/cm2 and 0.049%)

Nanostructured semiconductor materials for dye-sensitized solar cells

Since O'Regan and Grätzel's first report in 1991, dye-sensitized solar cells (DSSCs) appeared immediately as a promising low-cost photovoltaic technology. In fact, though being far less efficient than conventional silicon-based photovoltaics (being the maximum, lab scale prototype reported efficiency around 13%), the simple design of the device and the absence of the strict and expensive manufacturing processes needed for conventional photovoltaics make them attractive in small-power applications especially in low-light conditions, where they outperform their silicon counterparts. Nanomaterials are at the very heart of DSSC, as the success of its design is due to the use of nanostructures at both the anode and the cathode. In this review, we present the state of the art for both n-type and p-type semiconductors used in the photoelectrodes of DSSCs, showing the evolution of the materials during the 25 years of history of this kind of devices. In the case of p-type semiconductors, also some other energy conversion applications are touched upon. © 2017 Carmen Cavallo et al

Influence of the conditions of sensitization on the characteristics of p-DSCs sensitized with asymmetric squaraines

The effect of the conditions of sensitization on the photoelectrochemical performance of p-type dye-sensitized solar cells (p-DSCs) with screen-printed nickel oxide (NiO) photocathodes is analyzed. The dye-sensitizers employed in the present study are asymmetric squaraines. The conditions of sensitization differ for the relative concentration of the anti-aggregating agentCDCA(chenideoxycholic acid) with respect to the concentration of the dye-sensitizer. The co-adsorption of CDCA onto NiO electrode brings about a decrease in the surface concentration of the anchored dye as well as a blueshift of the characteristic wavelengths of optical absorption of the asymmetric squaraines considered here. Beside this, the employment of CDCA as co-adsorbent reduces the overall conversion performance of the resulting squaraine-sensitized p-DSCs with consequent diminution of the short-circuit current density. This result is ascribed to the acid action of CDCA toward the amminic nitrogen of the squaraines. Quantum efficiency spectra show that CDCA acts as a quencher of the intrinsic photoelectrochemical activity of NiO. Moreover, CDCA does not interfere with the mechanism of charge injection effectuated by the photoexcited squaraines. The photoelectrochemical impedance spectra was analyzed employing a model of equivalent circuit developed for semiconducting nanostructure electrodes

Characterization of Screen-Printed Nickel Oxide Electrodes for p-type Dye-Sensitized Solar Cells

Mesoporous NiO films obtained via screen-printing deposition of a newly formulated paste containing preformed NiO-nanospheres have been employed as nanostructured photocathodes of p-type dye-sensitized solar cells (p-DSCs). The novel aspect of this contribution is the utilization of a diluted solution of weak acid as anti-aggregating agent of NiO nanoparticles during the preparation of the screen-printing precursor. Screen printed NiO cathodes of p-DSCs displayed photoactivity in both bare and sensitized states with overall efficiencies not higher than 0.05% when erythrosine b (ERY) was the colorant and I3-/I- the redox mediator. The charge recombination resistance of NiO photocathodes in the illuminated p-DSCs diminished from 230 to 90 Ω with the increase of cell efficiency in going from the pristine oxide to its ERY sensitized version. In absence of a redox mediator, the NiO electrodes here considered displayed electroactivity due to the occurrence of solid state oxidation processes in the range 0.1-1.0 V vs Ag/AgCl. From the modelling of the electrochemical impedance data the total electrical resistance Rtot of screen printed NiO decreased drastically in passing from the pristine (1*105 - 6*105 Ω) to the oxidized state (20 - 150 Ω). The fitting parameter Rtot combined the two terms of bulk transport and charge transfer at the NiO/electrolyte interface. Rtot depended on NiO film thickness and on the nature of the electrolyte in a non-straightforward manner for the verification of electrochemically induced processes of NiO film dissolution

Limits on the use of cobalt sulfide as anode of p-type dye-sensitized solar cells

Thin films of cobalt sulfide (CoS) of thickness l < 10m have been employed as anodes of p-type dye-sensitized solar cells (p-DSCs) when P1-sensitized nickel oxide (NiO) was the photoactive cathode and /I - constituted the redox mediator. In the role of counter electrode for p-DSCs, CoS was preferred over traditional platinized fluorine-doped indium oxide (Pt-FTO) due to the lower cost of the starting materials (Co salts) and the easier procedure of deposition onto large area substrates. The latter process was carried out via direct precipitation of CoS from aqueous solutions. The photoconversion efficiency (η) of the corresponding device was 0.07%. This value is about 35% less than the efficiency that is obtained with the analogous p-DSC employing the Pt-FTO anode (η = 0.11). Unlike p-DSCs based on Pt-FTO anodes, the photoelectrochemical cells employing CoS electrodes showed that this anodic material was not able to sustain the photocurrent densities generated by P1-sensitized NiO at a given photopotential. Illumination of the p-DSCs with CoS anodes and P1-sensitized NiO cathodes actually induced the reverse bias of the photoelectrochemical cell with CoS behaving like a p-type semiconductor with no degeneracy. © 2017 IOP Publishing Ltd

A New Algorithm for The Surgical Management of Defects of the Scalp

Scalp reconstruction is a daily challenge for plastic surgeons. The authors propose their algorithm for reconstructive surgery after ablative surgery. They considered not only the size defect but also the anatomical defect and the clinical condition of the patient to achieve the best choice for reconstruction. During the two-year period, a total of 86 procedures were performed on 78 patients. We used five different techniques for reconstruction, including primary closure, graft, local or free flap, and a dermal regeneration template. No statistical difference of complication was observed in the different groups. We consider our algorithm a useful improvement in the management of the defect at the vertex.</jats:p

Partial T cell defects and expanded CD56bright NK cells in an SCID patient carrying hypomorphic mutation in the IL2RG gene

X-linked severe combined immunodeficiency (X-SCID) caused by full mutation of the IL2RG gene leads to T- B+ NK- phenotype and is usually associated with severe opportunistic infections, diarrhea, and failure to thrive. When IL2RG hypomorphic mutation occurs, diagnosis could be delayed and challenging since only moderate reduction of T and NK cells may be present. Here, we explored phenotypic insights and the impact of the p.R222C hypomorphic mutation (IL2RGR222C ) in distinct cell subsets in an 8-month-old patient with atypical X-SCID. We found reduced CD4+ T cell counts, a decreased frequency of naïve CD4+ and CD8+ T cells, and an expansion of B cells. Ex vivo STAT5 phosphorylation was impaired in CD4+ CD45RO+ T cells, yet compensated by supraphysiological doses of IL-2. Sanger sequencing on purified cell subsets showed a partial reversion of the mutation in total CD3+ cells, specifically in recent thymic emigrants (RTE), effector memory (EM), and CD45RA+ terminally differentiated EM (EMRA) CD4+ T cells. Of note, patient's NK cells had a normal frequency compared to age-matched healthy subjects, but displayed an expansion of CD56bright cells with higher perforin content and cytotoxic potential, associated with accumulation of NK-cell stimulatory cytokines (IL-2, IL-7, IL-15). Overall, this report highlights an alteration in the NK-cell compartment that, together with the high disease-phenotype variability, should be considered in the suspicion of X-SCID with hypomorphic IL2RG mutation

A Transition in the Accretion Properties of Radio-Loud Active Nuclei

We present evidence for the presence of a transition in the accretion properties of radio-loud sources. For a sample of radio galaxies and radio-loud quasars, selected based on their extended radio properties, the accretion rate is estimated from the black hole mass and nuclear luminosity. The inferred distribution is bimodal, with paucity of sources at accretion rates, in Eddington units, of order ~ 10^{-2} - assuming a radiative efficiency of 10 per cent - and possibly spanning one-two orders of magnitude. Selection biases are unlikely to be responsible for such behavior; we discuss possible physical explanations, including a fast transition to low accretion rates, a change in the accretion mode/actual accretion rate/radiative efficiency, the lack of stable disc solutions at intermediate accretion rates or the inefficiency of the jet formation processes in geometrically thin flows. This transition might be analogous to spectral states (and jet) transitions in black hole binary systems.Comment: 14 pages, 4 figures - Accepted for publication in MNRA

Evaluation of Clinicopathological and Molecular Parameters on Disease Recurrence of Papillary Thyroid Cancer Patient: A Retrospective Observational Study

The American Joint Committee on Cancer has revised the Tumor-Node-Metastasis (TNM) staging system for papillary thyroid cancer (PTC) patients. We examined the impact of this new classification (TNM-8) on patient stratification and estimated the prognostic value of clinicopathological features for the disease-free interval (DFI) in a cohort of 1148 PTC patients. Kaplan-Meier analyses showed that all clinicopathological parameters analyzed, except age and multifocality, were associated significantly with DFI. Cox regression identified tall cell PTC variant and stage as independent risk factors for DFI. When the stage was replaced with age, tumor size, and lymph node (LN) metastases in the set of covariates, the lateral LN metastases stood out as the strongest independent predictor of DFI, followed by tall cell variant and age. A noteworthy result emerging from these analyzes is that regression models had lower Akaike and Bayesian information criterions if variables were categorized based on the TNM-7. In addition, we examined data from a different PTC patient cohort, acquired from The Cancer Genome Atlas database, to verify whether the DFI prediction could be enhanced by further clinicopathological and molecular parameters. However, none of these was found to be a significant predictor of DFI in the Cox model

MORFEO enters final design phase

MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly MAORY), the MCAO system for the ELT, will provide diffraction-limited optical quality to the large field camera MICADO. MORFEO has officially passed the Preliminary Design Review and it is entering the final design phase. We present the current status of the project, with a focus on the adaptive optics system aspects and expected milestones during the next project phase