2,196 research outputs found

    New Earth-Abundant Thin Film Solar Cells Based on Chalcogenides.

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    At the end of 2017 roughly 1.8% of the worldwide electricity came from solar photovoltaics (PV), which is foreseen to have a key role in all major future energy scenarios with an installed capacity around 5 TW by 2050. Despite silicon solar cells currently rule the PV market, the extremely more versatile thin film-based devices (mainly Cu(In,Ga)Se2 and CdTe ones) have almost matched them in performance and present room for improvement. The low availability of some elements in the present commercially available PV technologies and the recent strong fall of silicon module price below 1 $/Wp focused the attention of the scientific community on cheap earth-abundant materials. In this framework, thin film solar cells based on Cu2ZnSnS4 (CZTS) and the related sulfur selenium alloy Cu2ZnSn(S,Se)4 (CZTSSe) were strongly investigated in the last 10 years. More recently, chalcogenide PV absorbers potentially able to face TW range applications better than CZTS and CZTSSe due to the higher abundance of their constituting elements are getting considerable attention. They are based on both MY2 (where M = Fe, Cu, Sn and Y = S and/or Se) and Cu2XSnY4 (where X = Fe, Mn, Ni, Ba, Co, Cd and Y = S and/or Se) chalcogenides. In this work, an extensive review of emerging earth-abundant thin film solar cells based on both MY2 and Cu2XSnY4 species is given, along with some considerations on the abundance and annual production of their constituting elements

    Using foraminifera in STEMSEAS Site 1 to understand the recent paleoceanographic and paleoclimatic history of Tanner Basin, California Borderland

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    In May of 2016, the STEMSEAS Educational Transit cruise OC1605-tranA collected the STEMSEAS Site 1 core from the Tanner Basin in the California Borderland. This research serves as the first formal survey of the foraminifera preserved within that core. The purpose of this research is to use foraminifera preserved within that core to understand the recent depositional and paleoenvironmental conditions at Site 1, and to place that information into a regional paleoceanographic and paleoclimatic context. In pursuing this purpose, this research aims to answer three questions: 1) Can biostratigraphic markers in the foraminiferal assemblages in STEMSEAS Site 1 core be used to test the hypothesis that a shift in elemental ratio concentrations at 120 cmbsf marks the Pleistocene/Holocene boundary? 2) Is there evidence of turbidity flow deposition at STEMSEAS Site 1? 3) Can the foraminiferal assemblages within STEMSEAS Site 1 core be used to study paleoenvironmental changes in the California Borderland through time? Thirty-four samples of the \u3e63 mm size sediment fraction from the core were analyzed throughout this study, and the data from those samples was compared with lithologic and elemental data collected by the STEMSEAS cruise shipboard party and with regional data. Additionally, radiocarbon dates were obtained to develop an age model for the core, which allowed cored data to be interpreted in a temporal context. In answering the proposed questions, the study found that: 1) The shift in elemental data at 120 cmbsf occurs very close to (~1 kyr following) the Pleistocene/Holocene boundary, and the Pleistocene/Holocene transition represents a period of low dissolved oxygen supply within the Tanner Basin and low surface productivity. 2) A small percentage of benthic foraminifera present at Site 1 were displaced to Site 1 from a shallower depth, suggesting that turbidity flows did impact sedimentation at this location, but were not the dominant sediment transport process. 3) The core records a paleoenvironmental history of semi-regular millennial scale variation in sea surface temperature, upwelling strength, and nutrient influx that may be driven by oscillating and increasing frequency of El Niño/Southern Oscillation events

    Cysteinylation and homocysteinylation of plasma protein thiols during ageing of healthy human beings

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    The purpose of the present study was to determine the relative amount of S-thiolated proteins (i.e. S-homocysteinylated, S-cysteinylglycinylated, S-glutathionylated and S-cysteinylated proteins) to the total protein thiols (i.e. the sum of reduced protein sulphydryl groups (PSHs) and protein mixed disulphides with homocysteine [HcySH], cysteinylglycine, cysteine [CysSH] and glutathione) in the plasma of healthy individuals aged 20 to 93. After plasma separation, total protein thiols, S-thiolated proteins, as well as CysSH, cystine, HcySH and homocystine were measured by high-performance liquid chromatography (HPLC) with fluorescence determination of the thiol-monobromobimane conjugate. Determination of plasma levels of protein thiols was performed by spectrophotometry with 5,5′-dithiobis(2-nitrobenzoic acid) as a titrating agent. The present study demonstrates an age-dependent reduction in the amount of PSHs, and an age-dependent increase in cysteinylated and homocysteinylated plasma proteins in healthy human beings. This indicates that the efficiency of the reduced protein thiol pool as an antioxidant defence system decreases with age, possibly causing an increased risk of irreversible oxidation (i.e. further oxidation to sulphinic and sulphonic acids, which are usually not reducible by thiol reducing agents) of sulphydryl groups of plasma proteins. The drop in the plasma level of protein sulphydryl groups suggests depletion and/or impairment of the antioxidant capacity of plasma, likely related to an alteration of the delicate balance between the different redox forms of thiols

    Pre-treatment high-sensitivity troponin T for the short-term prediction of cardiac outcomes in patients on immune checkpoint inhibitors

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    Background: Immune checkpoint inhibitors (ICIs) are an emerging option for several advanced metastatic cancers, but may have cardiotoxic effects. The prognostic value of high-sensitivity troponin T (hs-TnT) before treatment start has never been investigated. Materials and methods: Thirty consecutive patients underwent measurement of hs-TnT before starting ICI therapy (pembrolizumab, 23%; nivolumab, 12%; atezolizumab, 6%; durvalumab, 5%). The primary endpoint of cardiovascular death, stroke or transient ischaemic attack, pulmonary embolism and new-onset heart failure, and the secondary endpoint of progression of cardiac involvement according to the CARDIOTOX classification were evaluated after 3 months from the first cycle. Results: Patients (median age 68 years, 77% men, 13% with coronary artery disease, 90% current or former smokers, 67% overweight or obese and 43% hypertensive) had a median hs-TnT of 12 ng/L (interquartile interval 8-23). The primary endpoint occurred only in patients with hs-TnT â‰¥ 14 ng/L at baseline. Therefore, only patients who had hs-TnT â‰¥ 14 ng/L before the first cycle died had a stroke/TIA or new-onset HF. Furthermore, nine out of 13 patients with the secondary endpoint (progression of cardiac disease) had hs-TnT â‰¥ 14 ng/L before the first cycle (P =.012). AUC values were 0.909 for the primary endpoint and 0.757 for the secondary endpoint. The best cut-off was 14 ng/L for both the primary (100% sensitivity, 73% specificity) and secondary endpoints (sensitivity 75%, specificity 77%). Conclusions: In patients on ICIs, baseline hs-TnT predicts a composite cardiovascular endpoint and the progression of cardiac involvement at 3 months, with 14 ng/L as the best cut-off

    Key Success Factors and Future Perspective of Silicon-Based Solar Cells

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    Today, after more than 70 years of continued progress on silicon technology, about 85% of cumulative installed photovolatic (PV) modules are based on crystalline silicon (c-Si). PV devices based on silicon are the most common solar cells currently being produced, and it is mainly due to silicon technology that the PV has grown by 40% per year over the last decade. An additional step in the silicon solar cell development is ongoing, and it is related to a further efficiency improvement through defect control, device optimization, surface modification, and nanotechnology approaches. This paper attempts to briefly review the most important advances and current technologies used to produce crystalline silicon solar devices and in the meantime the most challenging and promising strategies acting to increase the efficiency to cost/ratio of silicon solar cells. Eventually, the impact and the potentiality of using a nanotechnology approach in a silicon-based solar cell are also described
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