The clustering instability of inertial particles spatial distribution in turbulent flows

A theory of clustering of inertial particles advected by a turbulent velocity field caused by an instability of their spatial distribution is suggested. The reason for the clustering instability is a combined effect of the particles inertia and a finite correlation time of the velocity field. The crucial parameter for the clustering instability is a size of the particles. The critical size is estimated for a strong clustering (with a finite fraction of particles in clusters) associated with the growth of the mean absolute value of the particles number density and for a weak clustering associated with the growth of the second and higher moments. A new concept of compressibility of the turbulent diffusion tensor caused by a finite correlation time of an incompressible velocity field is introduced. In this model of the velocity field, the field of Lagrangian trajectories is not divergence-free. A mechanism of saturation of the clustering instability associated with the particles collisions in the clusters is suggested. Applications of the analyzed effects to the dynamics of droplets in the turbulent atmosphere are discussed. An estimated nonlinear level of the saturation of the droplets number density in clouds exceeds by the orders of magnitude their mean number density. The critical size of cloud droplets required for clusters formation is more than $20 \mu$m.Comment: REVTeX 4, 15 pages, 2 figures(included), PRE submitte

Role of Polyamine-Induced Dimerization of Antizyme in Its Cellular Functions

Funding: This work was supported by grants from the Russian Science Foundation (grant # 17-74-20049—synthesis of C-methylated Spd analogues, ITC studies of dimerization of OAZ1, and frameshifting experiments), the Russian Science Foundation (grant # 19-74-10086—isolation of OAZ1, electrophoresis studies of dimerization of OAZ1), and the Academy of Finland (grants # 292574 and # 315487). Acknowledgments: The authors thank A. Karppinen, A. Korhonen, T. Reponen, M. Salminkoski, and S.D. Negrya for their skillful technical assistance.Peer reviewedPublisher PD

Long-term results and complication following Achilles tendon rupture repair

Introduction Currently, there is no consensus regarding optimal treatment options of Achilles tendon rupture. The purpose of this study was to evaluate long term results of Achilles tendon repair using different surgical techniques, assess complication rate and subjective satisfaction Methods The study included patients treated for Achilles tendon rupture using minimally invasive and open surgical repair. Complications including re-rupture, infection, deep vein thrombosis and neuropraxia were identified. In order to evaluate the factors influencing the risk of postoperative complications, logistic regression analysis was performed. The Achilles Tendon Rupture Score (ATRS) and the American Orthopedic Foot and Ankle Score (AOFAS) evaluated subjective outcomes. Results 130 patients with Achilles tendon tear were enrolled (123 primary and 7 revision cases). In primary repairs percutaneous technique was used in 60 % of cases (74/123), mini open technique – in 16 % (19/123), and open technique – in 24 % (30/123). Re-rupture occurred in 2.4 % of patients treated with minimally invasive techniques. There were no repeated ruptures following open repairs. Predominant number of infections was registered after open repairs and made 10 %, while minimally invasive techniques had 3.2 % of infections. Logistic regression analyses showed that steroid injection, open repair, application of tapes and autografts increased the risk of infectious complications. There were no significant differences in ATRS and AOFAS scores between different primary Achilles tendon repair techniques (p > 0.05). Discussion Results, obtained in the current study, are consistent with previously published data. Conclusions Open Achilles tendon repair showed a higher rate of infections, and lower rate of re-ruptures. The anamnesis of steroid injection, open repair, application of tapes and autografts increases the risk of infectious complications

Indocyanine Green-Containing Magnetic Liposomes for Constant Magnetic Field-Guided Targeted Delivery and Theranostics

The aim of the present study was to develop magnetic liposomes (MLPSs) incorporating an agent with the ability to act both as a photosensitizer and as a fluorophore for optical imaging. We therefore aimed to develop a preparation method for indocyanine green (ICG)-containing MLPS, followed by a detailed characterization of their physicochemical and magnetic properties. The ability of intravenously administered ICG-containing MLPSs to accumulate in tissue exposed to a constant magnetic field was tested in vivo. Using the thin film hydration method, 170-nm aqueous liposomes containing magnetic nanoparticles and indocyanine green were synthesized, followed by a detailed characterization of their physicochemical properties. It was shown that ICG-containing MLPSs possess the properties of T2 contrast for MRI. Apart from this, ICG-containing MLPSs were clearly visualized using near infrared fluorescent imaging, which was demonstrated in in vivo experiments showing an accumulation of ICG-containing MLPSs in the zone of magnetic field distribution produced by a previously implanted constant magnet in the tissue. Although not directly tested in the present study, therapeutic applications of ICG-containing MLPSs include magnetic hyperthermia, as well as the photodynamic, photothermal, and photoacoustic effects of ICG. Taking into account the fact that liposomes, iron oxide nanoparticles, and ICG are all FDA-approved agents, it is highly likely that ICG-containing MLPSs could be successfully translated to clinical practice

Indocyanine Green-Containing Magnetic Liposomes for Constant Magnetic Field-Guided Targeted Delivery and Theranostics

The aim of the present study was to develop magnetic liposomes (MLPSs) incorporating an agent with the ability to act both as a photosensitizer and as a fluorophore for optical imaging. We therefore aimed to develop a preparation method for indocyanine green (ICG)-containing MLPS, followed by a detailed characterization of their physicochemical and magnetic properties. The ability of intravenously administered ICG-containing MLPSs to accumulate in tissue exposed to a constant magnetic field was tested in vivo. Using the thin film hydration method, 170-nm aqueous liposomes containing magnetic nanoparticles and indocyanine green were synthesized, followed by a detailed characterization of their physicochemical properties. It was shown that ICG-containing MLPSs possess the properties of T2 contrast for MRI. Apart from this, ICG-containing MLPSs were clearly visualized using near infrared fluorescent imaging, which was demonstrated in in vivo experiments showing an accumulation of ICG-containing MLPSs in the zone of magnetic field distribution produced by a previously implanted constant magnet in the tissue. Although not directly tested in the present study, therapeutic applications of ICG-containing MLPSs include magnetic hyperthermia, as well as the photodynamic, photothermal, and photoacoustic effects of ICG. Taking into account the fact that liposomes, iron oxide nanoparticles, and ICG are all FDA-approved agents, it is highly likely that ICG-containing MLPSs could be successfully translated to clinical practice

Fluorescently Labeled Gadolinium Ferrate/Trigadolinium Pentairon(III) Oxide Nanoparticles: Synthesis, Characterization, In Vivo Biodistribution, and Application for Visualization of Myocardial Ischemia–Reperfusion Injury

Various gadolinium compounds have been proposed as contrasting agents for magnetic resonance imaging (MRI). In this study, we suggested a new synthesis method of gadolinium ferrate/trigadolinium pentairon(III) oxide nanoparticles (GF/TPO NPs). The specific surface area of gadolinium ferrate (GdFeO3) and trigadolinium pentairon(III) oxide (Gd3Fe5O12) nanoparticles was equal to 42 and 66 m2/g, respectively. The X-ray diffraction analysis confirmed that the synthesized substances were GdFeO3 and Gd3Fe5O12. The gadolinium content in the samples was close to the theoretically calculated value. The free gadolinium content was negligible. Biodistribution of the GF/TPO NPs was studied in rats by fluorescent imaging and Fe2+/Fe3+ quantification demonstrating predominant accumulation in such organs as lung, kidney, and liver. We showed in the in vivo rat model of myocardial ischemia–reperfusion injury that GF/TPO NPs are able to target the area of myocardial infarction as evidenced by the significantly greater level of fluorescence. In perspective, the use of fluorescently labeled GF/TPO NPs in multimodal imaging may provide basis for high-resolution 3D reconstruction of the infarcted heart, thereby serving as unique theranostic platform

Distribution of D1 dislocation luminescence centers in Si+-implanted silicon and the photoluminescence model

Using step-by-step removal of silicon layers, in which dislocation-related photoluminescence is observed after Si+ (100 keV, 1·1015 cm−2) ion implantation followed by high-temperature annealing in a chlorine containing atmosphere, it has been found that a majority of dislocation-related centers of luminescence at ~1.5 μm (D1 line) is localized at the depths of Si+ ion ranges. Cross-sectional electron microscopy shows that the dislocations introduced by the implantation treatment (implantation plus annealing) penetrate to depths of ~1 μm. A phenomenological model of the D1-line dislocation-related luminescence is developed based on the assumption that the K-centers and modified A-centers located in the atmospheres of dislocations are responsible for this luminescence line. The temperature dependence of luminescence intensity calculated on the basis of the model fits well the experimental data for the D1 line

Theranostic Platforms Based on Silica and Magnetic Nanoparticles Containing Quinacrine, Chitosan, Fluorophores, and Quantum Dots

In this paper, we describe the synthesis of multilayer nanoparticles as a platform for the diagnosis and treatment of ischemic injuries. The platform is based on magnetite (MNP) and silica (SNP) nanoparticles, while quinacrine is used as an anti-ischemic agent. The synthesis includes the surface modification of nanoparticles with (3-glycidyloxypropyl)trimethoxysilane (GPMS), the immobilization of quinacrine, and the formation of a chitosan coating, which is used to fix the fluorophore indocyanine green (ICG) and colloidal quantum dots AgInS2/ZnS (CQDs), which serve as secondary radiation sources. The potential theranostic platform was studied in laboratory animals