Search results for "Conversion"
showing 10 items of 707 documents
Parametric Frequency Conversion of Short Optical Pulses Controlled by a CW Background
2007
International audience; We predict that parametric sum-frequency generation of an ultra-short pulse may result from the mixing of an ultra-short optical pulse with a quasi-continuous wave control. We analytically show that the intensity, time duration and group velocity of the generated idler pulse may be controlled in a stable manner by adjusting the intensity level of the background pump.
ZnS Ultrathin interfacial layers for optimizing carrier management in Sb2S3-based photovoltaics
2021
Antimony chalcogenides represent a family of materials of low toxicity and relative abundance, with a high potential for future sustainable solar energy conversion technology. However, solar cells based on antimony chalcogenides present open-circuit voltage losses that limit their efficiencies. These losses are attributed to several recombination mechanisms, with interfacial recombination being considered as one of the dominant processes. In this work, we exploit atomic layer deposition (ALD) to grow a series of ultrathin ZnS interfacial layers at the TiO2/Sb2S3 interface to mitigate interfacial recombination and to increase the carrier lifetime. ALD allows for very accurate control over th…
Enamine-based hole transporting materials for vacuum-deposited perovskite solar cells
2020
In a short period of time, the rapid development of perovskite solar cells attracted a lot of attention in the science community with the record for power conversion efficiency being broken every year. Despite the fast progress in power conversion efficiency there are still many issues that need to be solved before starting large scale commercial applications, such as, among others, the difficult and costly synthesis and usage of toxic solvents for the deposition of hole transport materials (HTMs). We herein report new enamine-based charge transport materials obtained via a simple one step synthesis procedure, from commercially available precursors and without the use of expensive organomet…
Role of TiO2 in Highly Efficient Solar Cells
2021
Titanium dioxide (TiO2) is a naturally occurring oxide of titanium. It has a wide range of applications. It has three metastable phases, which can be synthesized easily by chemical routes. Usage of TiO2 in thin-film solar cells has gained much attention in increasing the performance of the cell. The objectives are to harvest the freely available earth’s energy and to gain expertise in yielding a maximum conversion efficiency. Various strategies are employed to face the challenges in improving the efficiency of solar cells. This study provides a broad view of the usage of different forms of TiO2 layers, like nanochannel, porous, nanotubes, and mesoporous layers, in enhancing electron injecti…
Nanotechnology in lithium niobate for integrated optic frequency conversion in the UV
2017
In the domain of Earth Explorer satellites nanoengineered nonlinear crystals can optimize UV tunable solid-state laser converters. Lightweight sources can be based on Lithium Niobate (LN) domain engineering by electric field poling and guided wave interactions. In this Communication we report the preliminary experimental results and the very first demonstration of UltraViolet second-harmonic generation by first-order quasi-phase-matching in a surface-periodically-poled proton-exchanged LN waveguide. The pump source was a Ti-Sapphire laser with a tunability range of 700- 980 nm and a 40 GHz linewidth. We have measured UV continuous-wave light at 390 nm by means of a lock-in amplifier and of …
The effect of intermittent feeding on feed intake and compensatory growth of whitefish Coregonus lavaretus L.
2009
Abstract Groups of juvenile whitefish, Coregonus lavaretus , were exposed for 6 weeks to three different feeding regimes: control (fed every day); 2 + 5 (fed during weekdays); and 2 + 2 (fed 2 days, starved 2 days). The fish in the 2 + 2 group ate and grew less than the controls but the 2 + 5 group was intermediate and did not differ statistically significantly from either of the other two groups. The fish in both treatment groups exhibited clear compensation for the reduced number of feeding days by increasing intake and consequently weight gain during the days when they were fed, and the compensation increased towards the end of the experiment. Feeding treatments induced clear changes in …
Optimization of Yarrowia lipolytica’s β-oxidation pathway for γ-decalactone production
2002
The yeast Yarrowia lipolytica growing on methyl ricinoleate produces various lactones, γ-decalactone, the worthy aroma compound, 3-hydroxy-γ-decalactone without sensorial properties and two decenolides of various interest. Unfortunately, these three latter lactones are produced at high levels by this yeast, decreasing yields and complicating the extraction of γ-decalactone. In this study, the production of γ-decalactone was increased through a genetic engineering of the strain and the accumulation of the three other lactones was lowered. Theses results show that it is possible to improve the mastering of the complex β-oxidation pathway (the metabolic pathway involved in these bioconversions…
Hepatocytes of double-transgenic mice expressing high levels of hepatitis B virus e antigen and interferon-gamma are not injured by HBeAg specific au…
2000
Seroconversion from HBeAg to alphaHBe of persons chronically infected by HBV is usually associated with a transient exacerbation of liver disease and subsequent normalization of liver histology. It is speculated that these clinico-pathological features may be due to the activation of cytodestructive mechanisms by alphaHBe antibodies. The aim of the present study was to investigate the pathogenic potential of alphaHBe antibodies in a transgenic mouse model. Therefore, alphaHBe autoantibodies were elicited in double-transgenic mice expressing high amounts of HBeAg and interferon-gamma in the liver. Interferon-gamma has reviously been shown to play an important role in the development of hepat…
Immunoglobulin M seropositivity for Toscana virus in a random population sample in Sicily.
2012
Summary Objectives High Toscana virus (TOSV) antibody seropositivity rates have been documented in the last decade, especially in the Mediterranean area. It is unclear if these rates are associated with a recent or past exposure to the virus. This is of importance, as primary infection can cause neurologic complications, especially in adults. The aim of the present study was to assess the current active TOSV circulation in western Sicily. Methods A cross-sectional seroprevalence study was conducted on 271 individuals aged 4–92 years, sampled from the general population of a small city. Each participant completed a self-administered questionnaire and provided serum, which was analyzed for th…
Toxoplasmosis, a severe complication in allogeneic hematopoietic stem cell transplantation: successful treatment strategies during a 5-year single-ce…
1999
Toxoplasmosis is a rare but often fatal complication that occurs after patients undergo allogeneic hematopoietic stem cell transplant. At our institution, toxoplasmosis was diagnosed in 8 of 301 patients who received stem cell transplants. Disseminated toxoplasmosis with a rapid fatal course was observed in 2 patients. Six patients had cerebral toxoplasmosis diagnosed on the basis of neurological signs and observation of the patients' mental confusion, seizures, and typical lesions (which were assessed by computed tomography, magnetic resonance imaging, or both). Seroconversion of antitoxoplasma immunoglobulin and a discovery of toxoplasma deoxyribonucleic acid in the cerebrospinal fluid (c…