Comparison of three radio-frequency discharge modes on the treatment of breast cancer cells in vitro

Non-thermal plasmas (NTPs) are known for their ability to induce thermal-free cytotoxic effects on cancer cells. However, as the variety of NTP devices increases, comparison of their cytotoxic effect becomes increasingly essential. In this work, we compare the cytotoxicity of three different radio-frequency NTPs. MDA-MB-231 triple negative breast cancer cells are treated in suspension in DMEM culture medium by the effluents of a single radiofrequency (RF) discharge device operating in three modes, namely the and modes of the capacitively coupled radio-frequency (CCRF) discharge and a RF plasma jet mode. All three discharge modes reduce the proliferative capacity of MDA-MB-231 cells, but the treatment time required to reach the same efficacy is more than ten times longer using the and the modes than using the jet mode. In all cases, using the appropriate treatment time, cells exhibit an impaired proliferation and eventually start to show signs of cell death (about 48 h after treatment). The three discharge modes also induce nuclear DNA damages. Plasma-produced H2O2 was not found to contribute to the cytotoxicity of the treatment. Furthermore, short-lived reactive species (gas phase or liquid phase species with a lifetime below 1 s) are expected to play a dominant role over the long-lived reactive species in the anti-cancer effect of all three discharge modes

Transition des basses fréquences aux hautes fréquences d’une décharge à barrière diélectrique en hélium à la pression atmosphérique

Réalisée en cotutelle avec l'Université de PerpignanLes décharges à barrière diélectrique homogènes à la pression atmosphérique représentent un véritable intérêt autant pour les applications industrielles que pour la richesse de leur comportement physique. Jusqu’à maintenant, la gamme des basses fréquences (sous 300 kHz) et la gamme des hautes fréquences (au-dessus de 3 MHz) ont été amplement étudiées ; la physique contrôlant la décharge est donc relativement bien connue. Par contre, la gamme des moyennes fréquences (entre 0,3 et 3 MHz) reste à ce jour très peu explorée. Cette thèse par article vise, dans un premier temps, à comprendre le fonctionnement de la décharge à barrière diélectrique dans la gamme des moyennes fréquences. Dans un deuxième temps, l’effet de la fréquence sur la décharge est étudié sur la plage des basses aux hautes fréquences. Cette recherche expérimentale est poursuivie à l’aide d’une décharge à barrière diélectrique dans une atmosphère contrôlée d’hélium à la pression atmosphérique. Afin d’identifier les multiples régimes de décharge, plusieurs diagnostics sont mis en oeuvre. L’imagerie rapide est d’abord employée pour permettre l’identification des régimes de décharge en fonction de leur évolution temporelle. Ensuite, des mesures électriques, de la spectroscopie d’émission optique et de la spectroscopie d’absorption sont utilisées de manière à déterminer la densité électronique, la température électronique ainsi que la densité des atomes dans un état métastable. Pour une fréquence d’excitation fixe dans la gamme des moyennes fréquences, la décharge peut se comporter selon deux régimes distincts. Ceux-ci sont identifiés comme le régime Ω, pour lequel l’ionisation se produit au centre de la décharge et la densité de puissance est d’environ 0,1W/cm3, et le régime hybride, pour lequel l’ionisation se produit dans les gaines et la densité de puissance est d’environs 10W/cm3. Lorsque la fréquence est supérieure à 1MHz, le passage du régime Ω au régime hybride est accompagné d’une hystérèse. Cette hystérèse est due au piégeage efficace des ions dans l’espace interdielectrique qui ne permet pas aux ions de participer à l’émission secondaire tant que la charge d’espace n’est pas suffisante pour déformer le champ électrique. Quant aux fréquences inférieures à 1MHz, le régime hybride qui leur est associé n’est pas maintenu de manière continue, mais transite spontanément entre les régimes Ω et hybride. Un phénomène qui est dû au piégeage des ions qui n’est pas encore suffisant pour conserver les ions dans la gaine dans le cas où le champ électrique est perturbé par la charge d’espace. De plus, sur toute la gamme de fréquences étudiée (de 25kHz à 15MHz), il est possible de générer plusieurs autres régimes de décharge homogènes. Jusqu’à 100 kHz, en plus du régime luminescent (pour lequel l’ionisation est maximum près de la cathode) habituellement observé en basses fréquences, un régime dit quasi-Townsend, pour lequel l’ionisation est à son maximum près de l’anode a pu être observé. Entre 200 et 3000 kHz, ce sont les régimes Ω et hybride qui sont observés. À partir de 5 MHz, le régime RF-α est finalement atteint. Sur la plage de fréquence étudiée, la densité électronique moyenne (intégrée spatialement et temporellement) varie de e14 à e17 /m3 tandis que la température électronique moyenne se situe entre 0.3 et 0,5 eV. Tout comme la température électronique, la densité des atomes dans un état métastable est maximale dans le régime hybride.Atmospheric-pressure diffuse discharges are of great interest both for their physical complexity as well as for their numerous industrial applications. A good method to generate diffuse discharges at atmospheric pressure is by means of a dielectric barrier discharge. Up to now, the low frequency range (below 300kHz) and the high-frequency range (above 3 MHz) have been vastly studied, leaving the medium frequency range (between 0.3 and 3 MHz) almost empty of experimental data. The aim of this thesis by publications is two fold. First, the discharge modes obtained in the medium frequency range are to be understood and characterized. Second, the influence of the excitation frequency on the discharge is studied over a wide spectrum (from 25 kHz to 15 MHz). This includes frequencies from the very-low-frequency range to the high-frequency range. The experimental investigation is undertaken with a dielectric barrier discharge in a well-controlled environment of helium at atmospheric pressure. In order to identify the multiple discharge modes, many diagnostics are performed. Fast imaging is used to identify discharge modes according to their time evolution. Then electrical measurements, optical emission spectroscopy and absorption spectroscopy are deployed to measure the electron density, the electron temperature and the density of atoms in a metastable state respectively. At a fix excitation frequency in the medium-frequency range, two distinct discharge modes occur. The first one is identified as the Ω mode in which ionization is at the centre of the discharge and the power density is about 0.1W/cm3. The second one is identified as the hybrid mode in which ionization mainly occurs in the sheath region and the power density can reach about 10W/cm3. When the frequency is above 1MHz, the transition from Ω mode to hybrid mode is subject to a hysteresis. This hysteresis is due to efficient trapping of ions in the gas gap which does not allow ions to participate in secondary electron emission as long as the space charge is too low to modify the applied electric field. However, when the frequency is below 1 MHz the hybrid mode can no longer be sustained continuously but rather oscillate spontaneously between the Ω and the hybrid mode. This phenomenon is due to less efficient ion trapping that cannot maintain ions in the sheath when the electric field is modified by the space charge. Furthermore, over the entire investigated frequency range, many other diffuse discharge modes are sustained. In addition to the atmospheric pressure glow discharge (in which maximum ionization occurs on the cathode side) usually observed in the low-frequency range, a Townsend-like mode is also generated at frequencies about 100kHz. In this case, the maximum ionization occurs on the anode side. From 200 to 3000kHz, the Ω and the hybrid mode are achieved. Finally, from 5 MHz, the usual RF-α mode is reached. Over the complete range of frequency investigated, the mean electron density (time and spatially averaged) increase from e14 to e17/m3 while the electron temperature ranges between 0.3 and 0.5 eV. Both electronic temperature and density of atoms in a metastable state are maximum in the hybrid mode

A simple high-speed random number generator with minimal post-processing using a random Raman fiber laser

ABSTRACT: A simple novel method for random number generation is presented, based on a random Raman fiber laser. This laser is built in a half-open cavity scheme, closed on one side by a narrow-linewidth 100 mm fiber Bragg grating. The interaction between the randomly excited lasing modes of this laser, in addition to nonlinear effects such as modulation instability, allow the generation of random bits at rates of up to 540 Gbps with minimal post processing. Evaluation of the resulting bit streams’ randomness by the NIST statistical test suite highlights the importance of evaluating the physical entropy content, as bit sequences generated by this random laser pass all the statistical tests with a significance level of 0.01, despite being generated at more than twice the theoretical entropy generation speed

Genome-wide gene expression profiling analysis of Leishmania major and Leishmania infantum developmental stages reveals substantial differences between the two species

<p>Abstract</p> <p>Background</p> <p><it>Leishmania </it>parasites cause a diverse spectrum of diseases in humans ranging from spontaneously healing skin lesions (e.g., <it>L. major</it>) to life-threatening visceral diseases (e.g., <it>L. infantum</it>). The high conservation in gene content and genome organization between <it>Leishmania major </it>and <it>Leishmania infantum </it>contrasts their distinct pathophysiologies, suggesting that highly regulated hierarchical and temporal changes in gene expression may be involved.</p> <p>Results</p> <p>We used a multispecies DNA oligonucleotide microarray to compare whole-genome expression patterns of promastigote (sandfly vector) and amastigote (mammalian macrophages) developmental stages between <it>L. major </it>and <it>L. infantum</it>. Seven per cent of the total <it>L. infantum </it>genome and 9.3% of the <it>L. major </it>genome were differentially expressed at the RNA level throughout development. The main variations were found in genes involved in metabolism, cellular organization and biogenesis, transport and genes encoding unknown function. Remarkably, this comparative global interspecies analysis demonstrated that only 10–12% of the differentially expressed genes were common to <it>L. major </it>and <it>L. infantum</it>. Differentially expressed genes are randomly distributed across chromosomes further supporting a posttranscriptional control, which is likely to involve a variety of 3'UTR elements.</p> <p>Conclusion</p> <p>This study highlighted substantial differences in gene expression patterns between <it>L. major </it>and <it>L. infantum</it>. These important species-specific differences in stage-regulated gene expression may contribute to the disease tropism that distinguishes <it>L. major </it>from <it>L. infantum.</it></p

Structural and optical properties of Nd:YAB-nanoparticle-doped PDMS elastomers for random lasers

ABSTRACT: We report the structural and optical properties of Nd:YAB (NdxY1−x Al3(BO3)4)-nanoparticle-doped PDMS elastomer films for random lasing (RL) applications. Nanoparticles with Nd ratios of x = 0.2, 0.4, 0.6, 0.8, and 1.0 were prepared and then incorporated into the PDMS elastomer to control the optical gain density and scattering center content over a wide range. The morphology and thermal stability of the elastomer composites were studied. A systematic investigation of the lasing wavelength, threshold, and linewidth of the laser was carried out by tailoring the concentration and optical gain of the scattering centers. The minimum threshold and linewidth were found to be 0.13 mJ and 0.8 nm for x = 1 and 0.8. Furthermore, we demonstrated that the RL intensity was easily tuned by controlling the degree of mechanical stretching, with strain reaching up to 300%. A strong, repeatable lasing spectrum over ~ 50 cycles of applied strain was observed, which demonstrates the high reproducibility and robustness of the RL. In consideration for biomedical applications that require long-term RL stability, we studied the intensity fluctuation of the RL emission, and confirmed that it followed Lévy-like statistics. Our work highlights the importance of using rare-earth doped nanoparticles with polymers for RL applications

Genome sequencing of the lizard parasite Leishmania tarentolae reveals loss of genes associated to the intracellular stage of human pathogenic species

The Leishmania tarentolae Parrot-TarII strain genome sequence was resolved to an average 16-fold mean coverage by next-generation DNA sequencing technologies. This is the first non-pathogenic to humans kinetoplastid protozoan genome to be described thus providing an opportunity for comparison with the completed genomes of pathogenic Leishmania species. A high synteny was observed between all sequenced Leishmania species. A limited number of chromosomal regions diverged between L. tarentolae and L. infantum, while remaining syntenic to L. major. Globally, >90% of the L. tarentolae gene content was shared with the other Leishmania species. We identified 95 predicted coding sequences unique to L. tarentolae and 250 genes that were absent from L. tarentolae. Interestingly, many of the latter genes were expressed in the intracellular amastigote stage of pathogenic species. In addition, genes coding for products involved in antioxidant defence or participating in vesicular-mediated protein transport were underrepresented in L. tarentolae. In contrast to other Leishmania genomes, two gene families were expanded in L. tarentolae, namely the zinc metallo-peptidase surface glycoprotein GP63 and the promastigote surface antigen PSA31C. Overall, L. tarentolae's gene content appears better adapted to the promastigote insect stage rather than the amastigote mammalian stage

Retinal lipid and glucose metabolism dictates angiogenesis through the lipid sensor Ffar1

Tissues with high metabolic rates often use lipids, as well as glucose, for energy, conferring a survival advantage during feast and famine1. Current dogma suggests that high-energy–consuming photoreceptors depend on glucose2, 3. Here we show that the retina also uses fatty acid β-oxidation for energy. Moreover, we identify a lipid sensor, free fatty acid receptor 1 (Ffar1), that curbs glucose uptake when fatty acids are available. Very-low-density lipoprotein receptor (Vldlr), which is present in photoreceptors4 and is expressed in other tissues with a high metabolic rate, facilitates the uptake of triglyceride-derived fatty acid5, 6. In the retinas of Vldlr−/− mice with low fatty acid uptake6 but high circulating lipid levels, we found that Ffar1 suppresses expression of the glucose transporter Glut1. Impaired glucose entry into photoreceptors results in a dual (lipid and glucose) fuel shortage and a reduction in the levels of the Krebs cycle intermediate α-ketoglutarate (α-KG). Low α-KG levels promotes stabilization of hypoxia-induced factor 1a (Hif1a) and secretion of vascular endothelial growth factor A (Vegfa) by starved Vldlr−/− photoreceptors, leading to neovascularization. The aberrant vessels in the Vldlr−/− retinas, which invade normally avascular photoreceptors, are reminiscent of the vascular defects in retinal angiomatous proliferation, a subset of neovascular age-related macular degeneration (AMD)7, which is associated with high vitreous VEGFA levels in humans. Dysregulated lipid and glucose photoreceptor energy metabolism may therefore be a driving force in macular telangiectasia, neovascular AMD and other retinal diseases

L'écriture laser femtoseconde comme vecteur d'intégration de la photonique au téléphone intelligent

RÉSUMÉ: L’intégration de structure photonique au téléphone intelligent au moyen de l’écriture au laser femtoseconde dans le verre de l’écran est une avenue afin de développer le potentiel de cette plate-forme technologique. La couche de verre formée de Gorilla glass® possède pour fonction primaire la protection de l’écran contre les intempéries et donc toute modification de son intégrité physique soulève la question à savoir si la fonction primaire se trouve compromise par la modification au laser femtoseconde (fs) du verre. Ainsi, la contrainte en rupture fut mesurée pour des échantillons sains et inscrits au laser fs pour plusieurs paramètres d’écriture (vitesse de 1 à 30 mm/s, énergie par impulsion de 0.495 à 1.32 μJ, profondeur de l’inscription de 20 à 200 μm et densité d’inscription par échantillon jusqu’à 50). Aucun changement significatif ne fut rapporté entre les échantillons vierges et inscrits du point de vue de l’analyse de Weibull et du test à deux paramètres de Kolmogorov-Smirnov. Parallèlement, dans l’espoir d’augmenter la valeur du changement d’indice de réfraction, un changement de régime d’écriture passant de 4 à 2 photons en doublant la fréquence du laser centré à 1030 nm, a été étudié. Une augmentation de 2 ordres de grandeur passant de Δn = 3 x 10-5 à Δn =1 x 10-3 est rapporté. Deux régimes d’écritures produisant des profils caractéristiques de changements d’indice ont été identifiés et sont respectivement régis par la présence d’accumulation thermique et la fluence. Plusieurs stratégies d’écriture de guide d’onde sont rapportées soit par inscription directe hors accumulation thermique, inscription directe avec accumulation thermique contrôlée, inscription de gaine et recouvrement dans le régime thermique. Le profil élancé des inscriptions causées par la filamentation est mis à contribution pour la production de volume de Raman-Nath (VRNG). Les paramètres d’écriture quant à la production de ces VRNG sont discutés en détail pour le verre des écrans, mais aussi dans une couche amovible d’aluminosilicate de verre protecteur d’écran. Afin de générer un spectromètre, un faible VRNG a été inscrit dans la couche amovible d’aluminosilicate placée devant la caméra frontale d’un téléphone Samsung Galaxy S21 FE. Une résolution optique de 3 nm et une résolution du détecteur de 0.4 nm/pixel ont été atteintes en utilisant le 2ième ordre de diffraction du VRNG de 3 μm de pas. La limite de détection en concentration de la rhodamine 6G en solution aqueuse fut mesurée à 0.5 mg/L ± 0.4 mg/L à titre démonstratif. ABSTRACT: The integration of photonic structures in the smartphone glass by means of femtosecond laser writing is an avenue to develop the potential of this technological platform. The glass layer formed from Gorilla glass® has as its primary function, the protection of the screen against the environment and therefore any modification of its physical integrity raises the question of whether the primary function is compromised by the femtosecond laser modification (fs ) of glass. Thus, the breaking stress was measured for pristine samples and inscribed with the fs laser with several writing parameters (speed from 1 to 30 mm/s, energy per pulse from 0.495 to 1.32 μJ, depth of the inscription from 20 to 200 μm and writing density per sample of up to 50). No significant changes were reported between the pristine and written samples in terms of Weibull analysis and the Kolmogorov-Smirnov two-parameter test. At the same time, in the hope of increasing the value of the refractive index change, a different writing regime from 4 to 2 photons by doubling the frequency of the 1030 nm laser was studied. An increase in the refractive index modification of 2 orders of magnitude from Δn = 3 x 10-5 to Δn = 1 x 10-3 is reported. Two writing regimes producing characteristic profiles of refractive index changes have been identified and are respectively governed by the presence of thermal accumulation and fluence. Several waveguide writing strategies are reported either by direct writing outside thermal accumulation, direct writing with controlled thermal accumulation, cladding writing and recovery in the thermal regime. The narrow profile of the inscriptions caused by the filamentation is put to use for the production of volume Raman-Nath grating (VRNG). The writing parameters, resulting in the production of these VRNGs, are discussed in detail for the screen glass, but also in a removable layer of aluminosilicate glass screen protector. In order to demonstrate a spectrometer, a weak VRNG was written into the removable layer of aluminosilicate and placed in contact with the front camera of a Samsung Galaxy S21 FE phone. An optical resolution of 3 nm and a detector resolution of 0.4 nm/pixel were achieved using the 2nd order VRNG diffraction of a 3 μm pitch grating. The concentration detection limit of rhodamine 6G in aqueous solution was measured at 0.5 mg/L ± 0.4 mg/L as a demonstration

Fs laser written volume Raman–Nath grating for integrated spectrometer on smartphone

Abstract In this work we demonstrate the integration of a spectrometer directly into smartphone screen by femtosecond laser inscription of a weak Raman–Nath volume grating either into the Corning Gorilla glass screen layer or in the tempered aluminosilicate glass protector screen placed in front of the phone camera. Outside the thermal accumulation regime, a new writing regime yielding positive refractive index change was found for both glasses which is fluence dependent. The upper-bound threshold for this thermal-accumulation-less writing regime was found for both glasses and were, respectively at a repetition rate less than 150 kHz and 101 kHz for fluence of 8.7 × 106 J/m2 and 1.4 × 107 J/m2. A weak volume Raman–Nath grating of dimension 0.5 by 3 mm and 3 μm pitch was placed in front of a Samsung Galaxy S21 FE cellphone to record the spectrum using the 2nd diffraction order. This spectrometer covers the visible band from 401 to 700 nm with a 0.4 nm/pixel detector resolution and 3 nm optical resolution. It was used to determine the concentration detection limit of Rhodamine 6G in water which was found to be 0.5 mg/L. This proof of concept paves the way to in-the-field absorption spectroscopy for quick information gathering