Research of the process of biological wastewater treatment under conditions of uneven load of the treatment system

The main purpose of the article is to develop a multifactorial model for rapid assessment of the efficiency of biological wastewater treatment reactors. A mathematical model of the process of biological wastewater treatment has been developed based on: changes in the concentration of organic contaminants in the bioreactor over time, taking into account the uneven flow of wastewater to the treatment plant, the process of substrate entering the bioreactor (different amounts may enter at different times). The software implementation of the proposed algorithm for solving the corresponding model problem in Python is carried out. The results of computer experiments on the study of the efficiency of wastewater treatment in biological treatment reactors for different operating conditions of facilities are presented. In particular, such processes were considered with taking into account the unevenness of the load, because the maximum cleaning loads are in the morning and in the evening. The task was solved to simulate a real situation and show how cleaning takes place at the maximum load at a certain time of the day. The results obtained will be useful for calculations in the design of biological treatment facilities or in the reconstruction of existing bioreactors for their prospective operation under new operating conditions

Simultaneous Multi-Harmonic Imaging of Nanoparticles in Tissues for Increased Selectivity

We investigate the use of Bismuth Ferrite (BFO) nanoparticles for tumor tissue labelling in combination with infrared multi-photon excitation at 1250 nm. We report the efficient and simultaneous generation of second and third harmonic by the nanoparticles. On this basis, we set up a novel imaging protocol based on the co-localization of the two harmonic signals and demonstrate its benefits in terms of increased selectivity against endogenous background sources in tissue samples. Finally, we discuss the use of BFO nanoparticles as mapping reference structures for correlative light-electron microscopy.Comment: 19 pages, 6 figure

Spinning-disc confocal microscopy in the second near-infrared window (NIR-II)

Fluorescence microscopy in the second near-infrared optical window (NIR-II, 1000–1350 nm) has become a technique of choice for non-invasive in vivo imaging. The deep penetration of NIR light in living tissue, as well as negligible tissue autofluorescence within this optical range, offers increased resolution and contrast with even greater penetration depths. Here, we present a custom-built spinning-disc confocal laser microscope (SDCLM) that is specific to imaging in the NIR-II. The SDCLM achieves a lateral resolution of 0.5 ± 0.1 μm and an axial resolution of 0.6 ± 0.1 μm, showing a ~17% and ~45% enhancement in lateral and axial resolution, respectively, compared to the corresponding wide-field configuration. We furthermore showcase several applications that demonstrate the use of the SDCLM for in situ, spatiotemporal tracking of NIR particles and bioanalytes within both synthetic and biological systems

Bismuth ferrite and silicon carbide harmonic nanoparticles: from characterization to tissue imaging

Ce travail poursuit l'étude des propriétés physiques des nanoparticules harmoniques et leur utilisation comme biomarqueurs en microscopie multiphotonique. D'abord nous démontrons le potentiel du carbure de silicium (SiC) pour l'imagerie, qui vient de ses propriétés de génération de seconde harmonique et fluorescence à deux photons. SiC a une efficacité non linéaire élevée et la microscopie multiphotonique confirme la possibilité de détecter de SiC dans des cellules. Nous étudions ensuite des nanoparticules (NPs) de ferrite de bismuth (BFO) préparés par la méthode de combustion comme un marqueur potentiel de bio-imagerie pour la microscopie multiphotonique. Les nanoparticules de BFO sont des nouveaux marqueurs prometteurs combinant un signal non linéaire très élevé et une réponse magnétique modérée. Des études de cytotoxicité, hémolytique et le mécanisme d'internalisation suggèrent une bonne biocompatibilité et un grand potentiel de BFO pour l'imagerie biomédicale dans des applications diagnostiques. Dans le dernier chapitre, nous abordons la question des émissions endogènes harmoniques du tissu. Nous montrons que l'émission multi-harmonique de BFO NPs peut facilement être détectée par microscopie multi-photon, en utilisant une excitation λ > 1 100 nm. Par des mesures de microscopie électronique supplémentaires, nous montrons que les NPs de BFO pourraient servir comme des marqueurs de localisation dans des études avancées de microscopie électronique et optique corrélatifs

Harmonic nanoparticles: noncentrosymmetric metal oxides for nonlinear optics

The combination of nonlinear optics and nanotechnology is an extremely rich scientific domain yet widely unexplored. We present here a review of recent optical investigations on noncentrosymmetric oxide nanoparticles with a large ${{\chi }^{(2)}}$ response, often referred to as harmonic nanoparticles (HNPs). HNPs feature a series of properties which distinguish them from other photonics nanoprobes (quantum dots, up-conversion nanoparticles, noble metal particles). HNPs emission is inherently nonlinear and based on the efficient generation of harmonics as opposed to fluorescence or surface plasmon scattering. In addition, the fully coherent signal emitted by HNPs together with their polarization sensitive response and absence of resonant interaction make them appealing for several applications ranging from multi-photon (infrared) microscopy and holography, to cell tracking and sensin

Tailoring single-cycle electromagnetic pulses in the 2–9 THz frequency range using DAST/SiO₂ multilayer structures pumped at Ti:sapphire wavelength

We present a numerical parametric study of single-cycle electromagnetic pulse generation in a DAST/SiO2 multilayer structure via collinear optical rectification of 800 nm femtosecond laser pulses. It is shown that modifications of the thicknesses of the DAST and SiO2 layers allow tuning of the average frequency of the generated THz pulses in the frequency range from 3 to 6 THz. The laser-to-THz energy conversion efficiency in the proposed structures is compared with that in a bulk DAST crystal and a quasi-phase-matching periodically poled DAST crystal and shows significant enhancement

Tailoring single-cycle electromagnetic pulses in the 2–9 THz frequency range using DAST/SiO_2 multilayer structures pumped at Ti:sapphire wavelength

We present a numerical parametric study of single-cycle electromagnetic pulse generation in a DAST/SiO2 multilayer structure via collinear optical rectification of 800 nm femtosecond laser pulses. It is shown that modifications of the thicknesses of the DAST and SiO2 layers allow tuning of the average frequency of the generated THz pulses in the frequency range from 3 to 6 THz. The laser-to-THz energy conversion efficiency in the proposed structures is compared with that in a bulk DAST crystal and a quasi-phase-matching periodically poled DAST crystal and shows significant enhancement.LPAPGR-HA

Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles

We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate. The multi-order polarization resolved emission curves are globally fitted with an analytical model to retrieve individual elements of susceptibility tensors

Non linear Plasmonic Nanohybrids as Probes for Multimodal Cell Imaging and Potential Phototherapeutic agent

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