Efficient hybrid solar cells based on solution processed mesoporous TiO2 / Tin (II) sulfide heterojunctions

Tin monosulfide (SnS) is emerging as a promising absorber material for the development of low-cost, solution-processable solar cells. Herein, we present a straightforward, solution-based route for the preparation of tin monosulfide (SnS) films employing a green solvent, namely, tetrahydrofuran (THF). We show that the surface coverage and the morphology of the SnS films can be tuned by modification of the precursor solution composition and film deposition conditions. Furthermore, we explore the effect of a PEDOT:PSS interlayer and fabricate solar cells based on the following architecture: FTO/planar-TiO2/mesoporous-TiO2/SnS/P3HT/PEDOT:PSS/Ag. Devices based on this architecture are shown to exhibit power conversion efficiencies (PCEs) of 3.0%, thus demonstrating the potential of our method for the development of low-cost and environmentally friendly solar cells

New Improved Photometric Redshifts of Galaxies in the HDF

We report new improved photometric redshifts of 1048 galaxies in the Hubble Deep Field (HDF). A standard chi^2 minimizing method is applied to seven-color UBVIJHK photometry by Fernandez-Soto, Lanzetta, & Yahil (1999). We use 187 template SEDs representing a wide variety of morphology and age of observed galaxies based on a population synthesis model by Kodama & Arimoto (1997). We introduce two new recipes. First, the amount of the internal absorption is changed as a free parameter in the range of E(B-V)=0.0 to 0.5 with an interval of 0.1. Second, the absorption due to intergalactic HI clouds is also changed by a factor of 0.5, 1.0, and 1.5 around the opacity given by Madau (1995). The total number of template SEDs is thus 187x6x3=3,366, except for the redshift grid. The dispersion sigma_z of our photometric redshifts with respect to spectroscopic redshifts is sigma_z=0.08 and 0.24 for z2, respectively, which are smaller than the corresponding values (sigma_z=0.09 and 0.45) by Fernandez-Soto et al. Improvement is significant, especially in z>2. This is due to smaller systematic errors which are largely reduced mainly by including three opacities due to intergalactic HI clouds. We discuss redshift distribution N(z) and cosmic star formation rate based on our new photometric redshifts.Comment: 24 pages including 16 eps figures; accepted for publication in Ap

HI Fluctuations at Large Redshifts: II - the Signal Expected for GMRT

For the GMRT, we calculate the expected signal from redshifted HI emission at two frequency bands centered at 610 and 325 MHz. The study focuses on the visibility-visibility cross-correlations, proposed earlier as the optimal statistical estimator for detecting and analyzing this signal. These correlations directly probe the power spectrum of density fluctuations at the redshift where the radiation originated, and thereby provide a method for studying the large scale structures at large redshifts. We present detailed estimates of the correlations expected between the visibilities measured at different baselines and frequencies. Analytic fitting formulas representing the salient features of the expected signal are also provided. These will be useful in planning observations and deciding an optimal strategy for detecting this signal.Comment: 16 pages including 7 figures, published in JAp

Sustained impairment of human cytomegalovirus (HCMV)-specific CD4+ and CD8+ T cell response is responsible for recurrent episodes of disseminated HCMV infection in a D+R- hand transplant recipient

Human cytomegalovirus (HCMV) infection is the major viral complication in solid organ transplant recipients. Seronegative recipents (R-) of organs from seropositive donors (D+) appear to be at higher risk of developing symptomatic HCMV infection. To what extent systemic life-threatening complications can be risked for non-life-saving transplant procedures? A case report describing successful treatment of repeated episodes of active HCMV infection in a D+R- hand recipient in the absence of HCMV-specific T-cell immunity is presented. In the attempt to save both the patient and the transplanted hand, a preemptive treatment strategy was adopted with the aim to boost the constitution of the virus-specific T-cell immune response and simultaneously avoid onset of disease. Careful monitoring of HCMV load in blood and HCMV-specific T-cell immunity guided administration of repeated courses of antiviral treatment and avoided emergence of HCMV-related symptoms. Following establishment of HCMV-specific CD4+ and CD8+ T-cell response, preemptive treatment was no longer required due to sustained HCMV disappearance from blood. The patient is now well, and his hand too. In conclusion, evaluation of virus-specific T-cell immunity is of crucial importance in D+R- transplant recipients and careful monitoring of HCMV-specific T cell mediated response should always parallel monitoring of HCMV load in transplant recipients

Improved Charge Separation and Photovoltaic Performance of BiI3 Absorber Layers by Use of an In Situ Formed BiSI Interlayer

Stable and nontoxic bismuth iodide (BiI3) is emerging as a promising absorber material for solar cell applications as it possesses favorable optical properties such as a narrow bandgap (1.7 eV) and a high absorption coefficient (105 cm–1) in the visible region. Despite these promising features, solar cells employing this material have only achieved power conversion efficiencies in the region of 1% as of yet, which is distant from the theoretical efficiency limit of 28%. It is reasonable to suppose that the relatively low performance of BiI3-based solar cells may originate from very short carrier lifetimes (180–240 ps) in BiI3, which makes efficient separation of mobile charges a crucial factor for the improvement of the photovoltaic performance of this material. Herein, transient optical spectroscopy is employed to show that the use of a bismuth sulfide iodide interlayer between the electron transport layer (ETL) and the bismuth iodide absorber promotes efficient charge separation. On the basis of this knowledge, we report BiI3 solar cells with a power conversion efficiency of 1.21% using a solar cell architecture comprised of ITO/SnO2/BiSI/BiI3/organic HTM/Au

Scaling hard vertical surfaces with compliant microspine arrays

A new approach for climbing hard vertical surfaces has been developed that allows a robot to scale concrete, stucco, brick and masonry walls without using suction or adhesives. The approach is inspired by the mechanisms observed in some climbing insects and spiders and involves arrays of microspines that catch on surface asperities. The arrays are located on the toes of the robot and consist of a tuned, multi-link compliant suspension. In this paper we discuss the fundamental issues of spine allometric scaling versus surface roughness and the suspension needed to maximize the probability that each spine will find a useable surface irregularity and to distribute climbing tensile and shear loads among many spines. The principles are demonstrated with a new climbing robot that can scale a wide range of exterior walls

Hydrodynamic simulations of the KT Eridani nova super-remnant

A nova super-remnant (NSR) is an immense structure associated with a nova that forms when frequent and recurrent nova eruptions sweep up surrounding interstellar material (ISM) into a high density and distant shell. The prototypical NSR, measuring over 100 pc across, was discovered in 2014 around the annually erupting nova M31N 2008-12a. Hydrodynamical simulations demonstrated that the creation of a dynamic NSR by repeated eruptions transporting large quantities of ISM is not only feasible but that these structures should exist around all novae, whether the white dwarf (WD) is increasing or decreasing in mass. But it is only the recurrent nova (RNe) with the highest WD masses and accretion rates that should host observable NSRs. KT Eridani is, potentially, the eleventh RNe recorded in the Galaxy and is also surrounded by a recently unveiled H{\alpha} shell tens of parsecs across, consistent with a NSR. Through modelling the nova ejecta from KT Eri, we demonstrate that such an observable NSR could form in approximately 50,000 years, which fits with the proper motion history of the nova. We compute the expected H{\alpha} emission from the KT Eri NSR and predict that the structure might be accessible to wide-field X-ray facilities.Comment: 9 pages, 7 figures; Accepted for publication in Monthly Notices of the Royal Astronomical Societ

Degradation mechanism of hybrid tin-based perovskite solar cells and the critical role of tin (IV) iodide

Tin perovskites have emerged as promising alternatives to toxic lead perovskites in next-generation photovoltaics, but their poor environmental stability remains an obstacle towards more competitive performances. Therefore, a full understanding of their decomposition processes is needed to address these stability issues. Herein, we elucidate the degradation mechanism of 2D/3D tin perovskite films based on (PEA)0.2(FA)0.8SnI3 (where PEA is phenylethylammonium and FA is formamidinium). We show that SnI4, a product of the oxygen-induced degradation of tin perovskite, quickly evolves into iodine via the combined action of moisture and oxygen. We identify iodine as a highly aggressive species that can further oxidise the perovskite to more SnI4, establishing a cyclic degradation mechanism. Perovskite stability is then observed to strongly depend on the hole transport layer chosen as the substrate, which is exploited to tackle film degradation. These key insights will enable the future design and optimisation of stable tin-based perovskite optoelectronics

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and late-stage age-related macular degeneration

Purpose: Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly in Western Countries. Evidence indicates that Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, a common genetic abnormality, may protect against ischemic heart and cerebrovascular disease, ocular vascular disorders, and colorectal cancer. This study was undertaken to ascertain whether G6PD deficiency may protect against AMD. Materials and Methods: 79 men with late-stage AMD and 79 male, age-matched cataract controls without AMD were recruited in March-December 2016. Smoking status, clinical history, and drug use were recorded. A blood sample was taken from each participant. Complete blood count, hemoglobin, glucose, creatinine, cholesterol, triglycerides, transaminases, bilirubin, and erythrocyte G6PD activity were measured. Stepwise logistic regression was used to investigate the association between G6PD deficiency and AMD. Results: G6PD deficiency was found in 7 (8.9%) AMD patients and 8 (10.1%) controls, a not statistically significant difference. Stepwise logistic regression disclosed that AMD was significantly associated with increased diastolic blood pressure (OR=1.09, 95% CI=1.03-1.15, P=0.02) and LDL-cholesterol (OR=1.02, 95% CI=1.0001-1.03, P=0.049) and lower values of white blood cell (WBC) count (OR=0.71, 95% CI=0.56-0.88, P=0.02) and aspartate aminotransferase (AST) (OR=0.92, 95% CI=0.85-0.99, P=0.044). Conclusion: Results suggest that G6PD deficiency has no protective effect on nor is a risk factor for AMD. Larger studies are necessary to confirm whether increased diastolic blood pressure and LDL-cholesterol and lower values of WBC count and AST are risk factors for AMD

Definition of indicators of appropriateness in the management of neovascular age-related macular degeneration: An expert opinion

Wet age-related macular degeneration is a chronic condition culminating, in most cases, in blindness. The introduction of anti-angiogenic agents in 2006 has represented a major breakthrough in the treatment of the disease, but timely and effective treatment with regular follow-up and monitoring is mandatory to stabilize and preserve visual acuity. In clinical practice, however, appropriate therapy provision is frequently challenged by economic and organizational issues that result in suboptimal visual outcomes and increased incidence of legal blindness. International Guidelines have defined a diagnostic and therapeutic pathway to ensure the best practice in wet age-related macular degeneration management, but reference parameters to evaluate and compare the performance of Retina Centers are lacking. To address the appropriateness of wet age-related macular degeneration management in Italy, a multidisciplinary panel of ten experts gathered in three meetings. They defined three sets of indicators and relative benchmark values that each Center should comply with to ensure patients optimal care already from the first access: (a) clinical intervention indicators, to determine the possible Center\u2019s deviation from the diagnostic and therapeutic pathway; (b) outcome indicator, to evaluate the socioeconomic impact of the healthcare systems\u2019 performance; (c) management indicators, to test the size of the gap between the Center\u2019s supply and demand. Once the indicators have been analyzed, healthcare systems can plan actions to improve appropriateness and monitor their effects. However, to put this in practice, a concerted effort by all parts involved in healthcare provision is required, together with adequate systems to analyze clinical and administrative documentation