Explore the vast range of titles available.

Cancer survivors suffer from progressive frailty, multimorbidity, and premature morbidity. We hypothesise that therapy-induced senescence and senescence progression via bystander effects are significant causes of this premature ageing phenotype. Accordingly, the study addresses the question whether a short anti-senescence intervention is able to block progression of radiation-induced frailty and disability in a pre-clinical setting. Male mice were sublethally irradiated at 5 months of age and treated (or not) with either a senolytic drug (Navitoclax or dasatinib + quercetin) for 10 days or with the senostatic metformin for 10 weeks. Follow-up was for 1 year. Treatments commencing within a month after irradiation effectively reduced frailty progression (p<0.05) and improved muscle (p<0.01) and liver (p<0.05) function as well as short-term memory (p<0.05) until advanced age with no need for repeated interventions. Senolytic interventions that started late, after radiation-induced premature frailty was manifest, still had beneficial effects on frailty (p<0.05) and short-term memory (p<0.05). Metformin was similarly effective as senolytics. At therapeutically achievable concentrations, metformin acted as a senostatic neither via inhibition of mitochondrial complex I, nor via improvement of mitophagy or mitochondrial function, but by reducing non-mitochondrial reactive oxygen species production via NADPH oxidase 4 inhibition in senescent cells. Our study suggests that the progression of adverse long-term health and quality-of-life effects of radiation exposure, as experienced by cancer survivors, might be rescued by short-term adjuvant anti-senescence interventions. Cancer treatments save lives, but they can also be associated with long-term side effects which greatly reduce quality of life; former patients often face fatigue, memory loss, frailty, higher likelihood of developing other cancers, and overall accelerated aging. Senescence is a change in a cell’s state that follows damage and is associated with aging. When a cell becomes senescent it stops dividing, can promote inflammation and may damage other cells. Research has shown that cancer treatment increases the numbers of cells entering senescence, potentially explaining the associated long-term side effects. A new class of drugs known as senolytics can kill senescent cells, but whether they could help to counteract the damaging effects of cancer treatments remain unclear. To explore this question, Fielder et al. focused on mice having received radiation therapy, which also exhibit the long-term health defects observed in human patients. In these animals, a single, short senolytic treatment after irradiation nearly erased premature aging; frailty did not increase faster than normal, new cancers were less prevalent, and the rodents retained good memory and muscle function for at least one year after irradiation. Even mice treated later in life, after frailty was already established, showed some improvement. In addition, multiple tissues, including the brain and the liver, hosted fewer senescent cells in the animals treated with senolytics, even up to old age. Research should now explore whether these remarkable effects could also be true for humans.

An unsteady analytical solution is proposed to predict the spreading rate of the crown generated by an impacting droplet onto wetted walls. The modelling strategy is based on the direct integration of the boundary layer correction into the potential flow solution that leads to the well-established square-root time dependence. The original potential flow has the structure of an unsteady, stagnation point flow with decaying strength. For initial strengths of the potential flow $a_0 \\geqslant 100\\ {\\rm s}^{-1}$, we find that a self-similar solution can also be obtained for the boundary layer in the variables $\\left (r \\sqrt {a(t)/(\\nu t)}, z \\sqrt {a(t)/(\\nu t)} \\right )$. The self-similarity of the solution enables a straightforward estimation of momentum losses during the spreading of the liquid layer along the wall. The proposed modelling approach yields an excellent agreement with experiments during the entire spreading phase. Moreover, it enables a smooth transition from the inertia-driven to the shear-controlled regime of crown propagation. In general, the analysis shows that momentum losses arising from viscous effects cannot be neglected during a significant portion of crown propagation, particularly for thin wall films.

Understanding the mobilisation of trapped globules of non-wetting phase during two-phase flow has been the aim of numerous studies. However, the driving forces for the mobilisation of the trapped phases are still not well understood. Also, there is little information about what happens within a globule before, at the onset and during mobilization. In this work, we used micro-particle tracking velocimetry in a micro-fluidic model in order to visualise the velocity distributions inside the trapped phase globules prior and during mobilisation. Therefore, time-averaged and instantaneous velocity vectors have been determined using fluorescent microscopy. As a porous medium, we used a polydimethylsiloxane (PDMS) micro-model with a well-defined pore structure, where drainage and imbibition experiments were conducted. Three different geometries of trapped non-wetting globules, namely droplets, blobs and ganglia were investigated. We observed internal circulations inside the trapped phase globules, leading to the formation of vortices. The direction of circulating flow within a globule is dictated by the drag force exerted on it by the flowing wetting phase. This is illustrated by calculating and analyzing the drag force (per unit area) along fluid-fluid interfaces. In the case of droplets and blobs, only one vortex is formed. The flow field within a ganglion is much more complex and more vortices can be formed. The circulation velocities are largest at the fluid-fluid interfaces, along which the wetting phase flows and decreases towards the middle of the globule. The circulation velocities increased proportionally with the increase of wetting phase average velocity (or capillary number). The vortices remain stable as long as the globules are trapped, start to change at the onset of mobilization and disappear during the movement of globules. They reappear when the globules get stranded. Droplets are less prone to mobilization; blobs get mobilised in whole; while ganglia may get ruptured and get mobilised only partially.

Considered are interactive relationships between a normal shock wave and the downstream shock wave leg of the associated lambda foot, as well as between a normal shock wave and time-varying static pressure as measured along the bottom surface of the test section. Such relationships are investigated as they vary with two different magnitudes of inlet unsteady Mach wave intensity and are characterized using shadowgraph flow visualization data, as well as power spectral density, magnitude-squared coherence, and time lag data. Employed for the investigation is a specialty test section with an inlet Mach number of 1.54, as utilized within a transonic/supersonic wind tunnel. The resulting data provide evidence of distinct interactions over a wide range of frequencies between the normal shock wave and the downstream shock wave leg of the lambda foot for low inlet unsteady Mach wave intensity. Note that these are not present in the same form and over the same ranges of frequency with high inlet unsteady Mach wave intensity. These differences are partially due to the location where flow events originate. The most significant sources of flow unsteadiness within the present investigation are mostly associated with the normal and oblique shock waves (with low inlet unsteady Mach wave intensity), and mostly with inlet flow disturbances from unsteady Mach waves (with high inlet unsteady Mach wave intensity). The present experimental results additionally evidence important connections between the normal shock wave and unsteady flow events within lower portions of the lambda foot, especially near the adjacent boundary layer separation region.

Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ~ 3 × 10⁵³ ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the γ-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropie energies.

To perform a fluid analysis for electroosmotic flows in micro- and nano-channels, it is necessary to mix various fluid contents in micro- and nano-scales. It is observed that fluids in electroosmotic flow exhibits Reynolds number effect as the flow exerts very weak inertial force and it requires long channel for mixing of different layers and species through diffusion process. Hence, if the desired length scale of mixing is large, an enormous time is needed for the molecules to be thoroughly mixed by diffusion. The theory of dynamic equations on time scale is used to study the stability of these systems. It is found that such a system may exhibits an unstable nature for overlapping electric double layer field with fluctuating velocities and stability is preserved for zero linear growth coefficient. To obtain an improved understanding of mixing performance, a numerical study is performed with the variation of channel height when more than one ionic species with channels patterned with heterogeneity is considered. The wall heterogeneity may be created by placing some blocks of unequal size (with or without charged) close to the channel wall or some external potential patches. The analytical results for the transport characteristics of electroosmotic flow obtained are compared with the direct numerical simulation of the Navier–Stokes equation, Nernst–Plank equation, and Poisson equation, simultaneously. It is shown that heterogeneous potential could generate complex flow structures and the increment of species layers at different levels of the channel cross section from inlet to outlet significantly improve the mixing rate.

Droplet and particle grouping can be influenced by applying an acoustic field and have practical applications such as particle scavenging and aerosol filters of engine exhaust and air purifiers. The present work experimentally investigates the influence of a standing acoustic wave on a single stream of droplets. The experimental setup consists of an acoustic transducer and a reflector plate through which the droplet stream passes in the presence or absence of an external pressure field generated by a standing acoustic wave. A droplet stream is generated with the help of a nozzle connected to a pressurized working fluid supply and piezoelectric transducer to control the spacing between droplets. The effect of the acoustic pressure field on the droplet stream generated by the nozzle operated at different piezoelectric excitation frequencies and fluid pressures is investigated. Droplet stream characteristics at every nozzle excitation frequency are observed with a high-speed camera when the acoustic field is switched OFF and ON. The competing effect of nozzle excitation frequency and acoustic field is observed. At lower nozzle frequencies, the nozzle generates an unstable stream of droplets having different sizes and spacings between them. When the acoustic field is applied at these lower frequencies, the stream of droplets becomes organized, and in some cases, it becomes equispaced and of the same size. However, an opposite behavior is observed at higher frequencies. In these cases, as the acoustic field is applied, an equispaced mono-disperse droplet stream becomes unstable due to the coalescence of droplets within the stream.

This paper presents an experimental and numerical analysis of swirl flow in a circular tube. Swirl flow is important for technical and natural processes, where high heat transfer and good fluid mixing are needed. Flow and vortex structures respecting redistribution of momentum and possible occurrence of vortex breakdown are taken into account. The swirl flow is analysed experimentally by the measurement of the velocity field using Particle Image Velocimetry (PIV) and numerically via the commercial CFD code ANSYS CFX. Three cases are investigated: laminar flow regime (Re = 1,000), intermediate flow regime (Re = 2,000), and turbulent flow regime (Re = 5,000). The redistribution of the velocity field and the decrease of the swirl strength towards the outlet are shown. This redistribution affects the Reynolds number. Concerning the Rossby number, the occurrence of vortex breakdown in the swirl flow is determined. It is shown that the vortex breakdown takes place in the flow with higher Reynolds numbers, where an axial backflow may occur. Changes of the Reynolds numbers Reϕ and Rez along the tube length also confirm this statement. Furthermore, a thermodynamic perspective of vortex breakdown phenomena is presented.

We present the potential of a quantitative temperature-based diagnostic approach for paper-based microfluidics, extending the work of Terzis et al. (J Colloid Interface Sci 504:751–757, 2017) which demonstrated a significant heat release at the liquid front during capillary-driven flows in cellulosic materials. Here, we investigate the applicability of biological fluids to provide a temperature rise at the imbibition front, and successfully demonstrate a monotonic trend between the level of local temperature rise and the concentration of specific analytes. In addition, effects of paper thickness and width are also examined.

This paper is concerned with the prediction of mass and momentum transport in turbulent wall jets developing over smooth and transitionally rough plane walls. The ability to accurately predict the resulting wall shear stresses and vertical profiles of the Reynolds stresses in these flows is prerequisite to the accurate prediction of bed scour, sediment re-suspension and transport by turbulent diffusion. The computations were performed by solving the Reynolds-averaged forms of the equations describing conservation of mass, momentum and concentration. The unknown correlations that arise from the averaging process (the Reynolds stresses in the case of the momentum equation, and the turbulent mass fluxes in the case of concentration) were obtained from the solution of modeled differential equations that describe their conservation. Since these models are somewhat more complex than those typically used in practice, their benefits are demonstrated by comparisons with results obtained from simpler, eddy-viscosity based closures. Comparisons with experimental data show that results of acceptable accuracy can be obtained only by using the appropriate combination of models for the turbulent fluxes of mass and momentum that properly account for the reduction of the Reynolds stresses due to wall damping effects, and for the modification of the mass transfer rates due to interactions with the mean rates of strain.