Effect of input pulse chirp on nonlinear energy deposition and plasma excitation in water

We analyze numerically and experimentally the effect of the input pulse chirp on the nonlinear energy deposition from $5\ \mu$J fs-pulses at $800$ nm to water. Numerical results are also shown for pulses at $400$ nm, where linear losses are minimized, and for different focusing geometries. Input chirp is found to have a big impact on the deposited energy and on the plasma distribution around focus, thus providing a simple and effective mechanism to tune the electron density and energy deposition. We identify three relevant ways in which plasma features may be tuned.Comment: 9 pages, 7 figure

Improved photostability in ternary blend organic solar cells:The role of [70]PCBM

Polymer solar cells are potentially key contributors to the next-generation organic photovoltaics for sustainable green sources of energy. In the past few years, ternary organic solar cells have emerged with promising characteristics. They have proven to yield high efficiency at about 15% for single junction donor:acceptor (D:A) solar cells. However, the low stability of organic solar cells is a hindrance to the commercialisation of this technology, and thus, needs more attention. Here, we show that with the right ratio of D : A1 : A2, ternary blend solar cells can be more efficient and more photostable than their D:A binary blend solar cells. We add [70]PCBM to PBDB-T:ITIC and PTB7-Th:ITIC binary blend solar cells in various ratios to fabricate ternary solar cells. The ternary solar cells outperform all binary cells in terms of efficiency and photostability with only a 10% average loss in efficiency under continuous illumination irrespective of the device structure. We identify changes in the molecular structure of the active layer blends as the main reason behind the observed degradation behaviour of the solar cells. The ternary blends are the most resilient to photo-induced molecular structural changes. This finding suggests that ternary organic solar cells could be a way to achieve photostable devices

Photostability of Fullerene and Non-Fullerene Polymer Solar Cells:The Role of the Acceptor

Recently, the advent of non-fullerene acceptors (NFAs) made it possible for organic solar cells (OSCs) to break the 10% efficiency barrier hardly attained by fullerene acceptors (FAs). In the past five years alone, more than hundreds of NFAs with applications in organic photovoltaics (OPVs) have been synthesized, enabling a notable current record efficiency of above 15%. Hence, there is a shift in interest towards the use of NFAs in OPVs. However, there has been little work on the stability of these new materials in devices. More importantly, there is very little comparative work on the photo-stability of FAs vs. NFAs solar cells, to ascertain the pros and cons of the two systems. Here, we show the photo-stability of solar cells based on two workhorse acceptors, in both conventional and inverted structures, namely ITIC (as NFA) and [70]PCBM (as FA) blended with either PBDB-T or PTB7-Th polymer. We found that irrespective of the polymer, the cell structure, or the initial efficiency, the [70]PCBM devices are more photo-stable than the ITIC ones. This observation, however, opposes the assumption that NFA solar cells are more photo-chemically stable. These findings suggest that complementary absorption should not take precedence in the design rules for the synthesis of new molecules and there is still work left to be done to achieve stable as well as efficient OSCs

Porphyromonas gingivalis Participates in Pathogenesis of Human Abdominal Aortic Aneurysm by Neutrophil Activation. Proof of Concept in Rats

International audienceBACKGROUND: Abdominal Aortic Aneurysms (AAAs) represent a particular form of atherothrombosis where neutrophil proteolytic activity plays a major role. We postulated that neutrophil recruitment and activation participating in AAA growth may originate in part from repeated episodes of periodontal bacteremia. METHODS AND FINDINGS: Our results show that neutrophil activation in human AAA was associated with Neutrophil Extracellular Trap (NET) formation in the IntraLuminal Thrombus, leading to the release of cell-free DNA. Human AAA samples were shown to contain bacterial DNA with high frequency (11/16), and in particular that of Porphyromonas gingivalis (Pg), the most prevalent pathogen involved in chronic periodontitis, a common form of periodontal disease. Both DNA reflecting the presence of NETs and antibodies to Pg were found to be increased in plasma of patients with AAA. Using a rat model of AAA, we demonstrated that repeated injection of Pg fostered aneurysm development, associated with pathological characteristics similar to those observed in humans, such as the persistence of a neutrophil-rich luminal thrombus, not observed in saline-injected rats in which a healing process was observed. CONCLUSIONS: Thus, the control of periodontal disease may represent a therapeutic target to limit human AAA progression

Filamentation and Pulse Self-compression in the Anomalous Dispersion Region of Glasses

International audienceThe propagation of near-infrared ultra-short laser pulses in the regime of anomalous dispersion of transparent solids is associated with a host of self-induced effects including a significant spectral broadening extending from the ultraviolet into the infrared region, pulse self-compression down to few-cycle pulse durations, free and driven third harmonic generation, conical emission and the formation of stable filaments over several cm showing the emergence of conical light bullets. We review measurements performed in different experimental conditions and results of numerical simulations of unidirectional propagation models showing that the interpretation of all these phenomena proceed from the formation of non-spreading conical light bullets during filamentation

Novel aspects of the pathogenesis of aneurysms of the abdominal aorta in humans

Aneurysm of the abdominal aorta (AAA) is a particular, specifically localized form of atherothrombosis, providing a unique human model of this disease. The pathogenesis of AAA is characterized by a breakdown of the extracellular matrix due to an excessive proteolytic activity, leading to potential arterial wall rupture. The roles of matrix metalloproteinases and plasmin generation in progression of AAA have been demonstrated both in animal models and in clinical studies. In the present review, we highlight recent studies addressing the role of the haemoglobin-rich, intraluminal thrombus and the adventitial response in the development of human AAA. The intraluminal thrombus exerts its pathogenic effect through platelet activation, fibrin formation, binding of plasminogen and its activators, and trapping of erythrocytes and neutrophils, leading to oxidative and proteolytic injury of the arterial wall. These events occur mainly at the intraluminal thrombus–circulating blood interface, and pathological mediators are conveyed outwards, where they promote matrix degradation of the arterial wall. In response, neo-angiogenesis, phagocytosis by mononuclear cells, and a shift from innate to adaptive immunity in the adventitia are observed. Abdominal aortic aneurysm thus represents an accessible spatiotemporal model of human atherothrombotic progression towards clinical events, the study of which should allow further understanding of its pathogenesis and the translation of pathogenic biological activities into diagnostic and therapeutic applications

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Theory of femtosecond strong field ion excitation and subsequent lasing in N2+

Delayed cavity-free forward lasing at the wavelengths of 391 and 428 nm was observed in recent experiments in air or pure nitrogen pumped with an intense femtosecond laser pulse at wavelength of 800 nm. The mechanism responsible for the lasing is highly controversial. In this article we propose a model explaining the delayed lasing, which contains two parts: (i) ionization of neutral nitrogen molecules and subsequent excitation of nitrogen ions in a strong pump laser pulse, and (ii) coherent emission of excited ions due to the presence of long-lived polarizations maintained by a weak laser post-pulse and coupling simultaneously ground state X 2 Σ + g to states A 2 Π u and B 2 Σ + u of singly ionized nitrogen molecules N + 2. Two regimes of signal amplification are identified: a signal of a few picosecond duration at low gas pressures and a short (sub-picosecond) signal at high gas pressures. The theoretical model compares favorably with results obtained by different experimental groups

Quantum Interference Between Transition Probability Amplitudes in N2+

International audienc