Steep Profile Research Articles

Detection of a Dense Group of Hypercompact Radio Sources in the Central Parsec of the Galaxy

Abstract Using the JVLA, we explored the Galactic center (GC) with a resolution of 0.″05 at 33.0 and 44.6 GHz. We detected 64 hypercompact radio sources (HCRs) in the central parsec. The dense group of HCRs can be divided into three spectral types: 38 steep-spectrum (α ≤ −0.5) sources, 10 flat-spectrum (−0.5 < α ≤ 0.2) sources, and 17 inverted-spectrum sources having α > 0.2, assuming S ∝ ν α . The steep-spectrum HCRs are likely to represent a population of massive stellar remnants associated with nonthermal compact radio sources powered by neutron stars and stellar black holes. The surface-density distribution of the HCRs as a function of radial distance (R) from Sgr A* can be described as a steep power law Σ(R) ∝ R −Γ, with Γ = 1.6 ± 0.2, along with the presence of a localized order-of-magnitude enhancement in the range 0.1–0.3 pc. The steeper profile of the HCRs relative to that of the central cluster might result from the concentration of massive stellar remnants by mass segregation at the GC. The GC magnetar SGR J1745−2900 belongs to the inverted-spectrum subsample. We find two spectral components present in the averaged radio spectrum of SGR J1745−2900, separated at ν ∼ 30 GHz. The centimeter component is fitted to a power law with α cm = −1.5 ± 0.6. The enhanced millimeter component shows a rising spectrum α mm = 1.1 ± 0.2. Based on the ALMA observations at 225 GHz, we find that the GC magnetar is highly variable on a day-to-day timescale, showing variations up to a factor of 6. Further JVLA and ALMA observations of the variability, spectrum, and polarization of the HCRs are critical for determining whether they are associated with stellar remnants.

Wave breaking probabilities under wind forcing in open sea and laboratory

Water wave breaking represents one of the most arduous problems in fluid mechanics. Understanding the process of wave breaking and developing an ability to quantify the associated energy losses and redistribution are critical across a wide range of coastal oceanic applications, maritime navigation, and climate and hydrodynamic research. Naturally, waves become steeper toward the inception of breaking; however, there is still a lack of unanimity regarding the relationship between breaking probability statistics and wave steepness. Here, we present a detailed investigation of breaking vs non-breaking statistics estimated using a recently developed method for accurate detection of breaking waves, based on the phase-time approach to identify breaking-associated patterns in the instantaneous frequency variations of surface elevation fluctuations. The findings are based on data collected both in the open sea and in a laboratory wind wave flume. An in-depth examination of celerities and steepnesses of breaking and non-breaking waves is presented. The analysis, which involved wave-by-wave examination, produced skewed Gaussian-like steepness histograms, revealing that non-breaking waves and breaking waves can reach steeper profiles, above the Stokes limit. All extreme steepness values were investigated and are presented here.

Lyα Radiative Transfer: A Stokes Vector Approach to Lyα Polarization

Abstract Lyα-emitting galaxies and giant Lyα blobs (LABs) have been extensively observed to study the formation history of galaxies. However, the origin of their extended Lyα emission, especially of LABs, remains controversial. Polarization signals from some LABs have been discovered, and this is commonly interpreted as strong evidence supporting that the extended Lyα emission originates from the resonance scattering. The Monte Carlo Lyα radiative transfer code LaRT is updated to investigate the polarization of Lyα using the Stokes vector formalism. We apply LaRT to a few models to explore the fundamental polarization properties of Lyα. Interestingly, individual Lyα photon packets are found to be almost completely polarized by a sufficient number of scatterings (N scatt ≳ 104–105 in a static medium) or Doppler shifts induced by gas motion, even starting from unpolarized light. It is also found that the polarization pattern can exhibit a nonmonotonically increasing pattern in some cases, other than the commonly known trend that the polarization monotonically increases with radius. The polarization properties are primarily determined by the degree of polarization of individual photon packets and the anisotropy of the Lyα radiation field, which are eventually controlled by the medium’s optical depth and velocity field. Once Lyα photon packets achieve ∼100% polarization, the radial profile of polarization appears to correlate with the surface brightness profile. A steep surface brightness profile tends to yield a rapid increase of the linear polarization near the Lyα source location. In contrast, a shallow surface brightness profile gives rise to a slowly increasing polarization pattern.

Constraints on ultracompact minihalos from the extragalactic gamma-ray background observation

Ultracompact minihalo (UCMH) is a special type of dark matter halo with a very steep density profile that may form in the early Universe seeded by an overdense region or a primordial black hole. Constraints on its abundance give valuable information on the power spectrum of primordial perturbation. In this work, we update the constraints on the UCMH abundance in the Universe using the extragalactic gamma-ray background observation. Comparing to previous works, we adopt the updated Fermi-LAT extragalactic gamma-ray background measurement and derive constraints based on a full consideration of the astrophysical contributions. With these improvements, we place constraints on UCMH abundance 1--2 orders of magnitude better than previous results. With the background components considered, we can also attempt to search for possible additional components beyond the known astrophysical contributions.

Radialization of Satellite Orbits in Galaxy Mergers

Abstract We consider the orbital evolution of satellites in galaxy mergers, focusing on the evolution of eccentricity. Using a large suite of N-body simulations, we study the phenomenon of satellite orbital radialization—a profound increase in the eccentricity of its orbit as it decays under dynamical friction. While radialization is detected in a variety of different setups, it is most efficient in cases of high satellite mass, not very steep host density profiles, and high initial eccentricity. To understand the origin of this phenomenon, we run additional simulations with various physical factors selectively turned off: satellite mass loss, reflex motion and distortion of the host, etc. We find that all these factors are important for radialization because it does not occur for point-mass satellites or when the host potential is replaced with an unperturbed initial profile. The analysis of forces and torques acting on both galaxies confirms the major role of self-gravity of both host and satellite in the reduction of orbital angular momentum. The classical Chandrasekhar dynamical friction formula, which accounts only for the forces between the host and the satellite, but not for internal distortions of both galaxies, does not match the evolution of eccentricity observed in N-body simulations.

Simulation prediction of micro-instability transition and associated particle transport in tokamak plasmas

Two reduced simulation approaches are exploited to predict the parametric boundary of dominant instability regime with global effects and the characteristics of corresponding turbulent particle fluxes in tokamak plasmas. One is usual numerical simulation of coexisting ion temperature gradient (ITG) mode and trapped electron mode (TEM) turbulence employing an extended fluid code (ExFC) based on the so-called Landau–Fluid model including the trapped electron dynamics. Here the density gradient (i.e. R/L n ) driven TEM (∇n-TEM) is emphasized. The other one is a surrogate turbulence transport model, taking a neural network (NN) based approach with speeding calculation. It is shown that the turbulent particle flux, particularly their directions depend on the type of micro-instability as ITG and/or TEM. On the other hand, the density gradient may govern the direction of the turbulent particle fluxes in general circumstances. Specifically, in the parameter regime explored here, the ITG and the electron temperature gradient driven TEM (∇T e-TEM) are destabilized for flat density profile, generally causing an inward particle flux, i.e. particle pinch. Contrarily, for steep density profile, the ∇n-TEM or coexisting ITG and TEM turbulence are dominant so that the particle always diffuses outwards. An empirical criterion is obtained to predict the dominant instability and the direction of particle flux for medium density gradients, involving the gradients of both ion and electron temperature as well as the density. These two transport models are applied to analyze the spontaneous excitation of a quasi-coherent mode in the turbulence modulation discharge by MHD magnetic island observed on tokamak HL-2A, clearly showing a dynamic transition from ITG to TEM. Furthermore, the ExFC-NN model can predict and speed up the analysis of the turbulence transport in tokamak experiments.

Smoothed Particle Hydrodynamics simulations of reef surf zone processes driven by plunging irregular waves

As waves interact with the slopes of coral reefs and other steep bathymetry profiles, plunging breaking usually occurs where the free surface overturns and violent water motion is triggered. Resolving these surf zone processes pose significant challenges for conventional mesh-based hydrodynamic models, due to the rapidly-deforming nature of the free surface and associated flows. Yet the accurate prediction of these surf zone hydrodynamics is critical for predicting a wide range of nearshore processes driven by wave breaking (e.g., wave dissipation and energy transfers; mean water levels and currents; and wave runup). In this study we assess the ability of the mesh-free, Lagrangian particle-based numerical modelling approach Smoothed Particle Hydrodynamics (SPH) based on DualSPHysics, to simulate the fine-scale hydrodynamic processes driven by irregular wave transformation over a fringing reef profile, by comparing results against detailed experimental observations from a physical modelling study. To greatly improve the computational efficiency, the SPH model was coupled to the mesh-based multi-layer nonhydrostatic wave-flow model SWASH. With this coupled approach, SWASH was used to efficiently simulate the evolution of non-breaking waves from the wavemaker up to the fore reef slope, with the SPH model then used to simulate the detailed hydrodynamic processes over the reef from just offshore of the breakpoint to the shoreline. The SPH model was able to accurately reproduce the complex free surface deformations during plunging breaking, the spectral evolution of waves across the reef flat (including nonlinear wave shape), the mean water levels and currents, and wave runup at the shoreline. Using the long duration simulations (>400 wave periods), the model was able to reproduce the full range of wave motions over the reef (from sea-swell to infragravity frequencies), including the increasing dominance of low frequency waves towards the shoreline and the large cross-reef standing wave motions excited by the reef geometry.

An Efficient Adaptive and Steep-Convergent Sidelobes Simultaneous Reduction Algorithm for Massive Linear Arrays

Antenna arrays have become an essential part of most wireless communications systems. In this paper, the unwanted sidelobes in the symmetric linear array power pattern are reduced efficiently by utilizing a faster simultaneous sidelobes processing algorithm, which generates nulling sub-beams that are adapted to control and maintain steep convergence toward lower sidelobe levels. The proposed algorithm is performed using adaptive damping and heuristic factors which result in learning curve perturbations during the first few loops of the reduction process and is followed by a very steep convergence profile towards deep sidelobe levels. The numerical results show that, using the proposed adaptive sidelobes simultaneous reduction algorithm, a maximum sidelobe level of −50 dB can be achieved after only 10 iteration loops (especially for very large antenna arrays formed by 256 elements, wherein the processing time is reduced to approximately 25% of that required by the conventional fixed damping factor case). On the other hand, the generated array weights can be applied to practical linear antenna arrays under mutual coupling effects, which have shown very similar results to the radiation pattern of the isotropic antenna elements with very deep sidelobe levels and the same beamwidth.

Sanbe volcano: Long‐term evolution of an arc magmatic system

AbstractA suite of samples was studied that represents the major explosive eruptions of Sanbe volcano, SW Japan. We demonstrate how rate of magma flux into the Trans‐Crustal Magmatic System (TCMS) presents a major control on the type and style of the subsequently forthcoming eruptions. Erupted products can be separated into two distinct groups. An older group is characterized by highly evolved, high‐K, LILE‐rich rhyolitic magmas, showing a supressed adakitic trace element signature (otherwise characteristic for the young stratovolcanoes in the SW Japan arc) with low Ca, Sr concentrations and a negative Eu anomaly. In contrast, the younger group (dominantly of andesitic—dacitic composition) displays a strong adakitic trace element signature with characteristic steep REE profiles and high Sr concentrations. An Eu anomaly is generally lacking here. The two groups are also distinct in their petrographic features, with the early group being almost aphyric showing simple log linear crystal size distributions and homogeneous, uniform mineral chemistries. In contrast, products of the younger group show complex crystal size distributions with diverse mineral compositions and abundant disequilibrium features. Our study shows that an initial high melt‐production rate allowed dehydration melting of lower crustal rocks leading to the formation of highly evolved K‐rich magmas. These magmas intruded into the shallow crust and produced two large Plinian rhyolitic, caldera forming eruptions. Subsequently the primary magma production rate decreased and the lower crust became too refractory for additional dehydration melting by these lower volume magma batches, causing the conventional adakitic magmatism to produced several additional eruptions of smaller magnitude, mainly of Sub‐Plinian or Pelean styles.

Refinements of Pin-Based Pointwise Energy Slowing-Down Method for Resonance Self-Shielding Calculation-II: Verifications

The pin-based pointwise energy slowing-down method (PSM) has been refined through eliminating the approximation for using the pre-tabulated collision probability during the slowing-down calculation. A collision probability table is generated by assuming that material composition and temperature are constant in the fuel pellet using the collision probability method (CPM). Refined PSM (PSM-CPM), which calculates the collision probability in the isolated fuel pellet during the slowing-down calculation using CPM, can consider nonuniform material and temperature distribution. For the methods, the extensive comparative analysis is performed with problems representing various possible conditions in a light water reactor (LWR) design. Conditions are categorized with the geometry, material distribution, temperature profile in the fuel pellet, and burnup. With test problems, PSMs (PSM and PSM-CPM) have been compared with conventional methods based on the equivalence theory. With overall calculation results, PSMs show the accuracy in the eigenvalue with differences in the order of 100 pcm compared to the reference results. There was no noticeable difference in the multigroup cross sections, reaction rates, and pin power distributions. However, PSM-CPM maintains the accuracy in the calculation of the fuel temperature coefficient under the condition with 200% power and nonuniform temperature distribution in the fuel pellet. PSM shows the difference in the eigenvalue in the order of 2,000 pcm for the fictitious pin-cell problem with highly steep temperature profiles and material compositions, but PSM-CPM shows the difference in the eigenvalue within 100 pcm.

Golden Horn Unkapanı Highway Tube Tunnel – Istanbul: Underwater bridge design in seismic environment

The Golden Horn in Istanbul is being crossed by several bridges, one of them to be replaced by a tunnel. The river has a steep profile with densely populated banks. Because of the planned connections to the boulevards, traditional solutions (immersed tunnel in a trench, TBM tunnel) proved not feasible. Commissioned by the Istanbul Metropolitan Municipality (IBB), Arcadis designed a shallow tunnel above the river bed. Because of the severe seismic conditions, the ability to respond to dynamic soil displacements without leakage or collapse was key in the design. The basic design philosophy was ‘limited flexibility’: flexible enough to follow the movements without build-up of detrimental forces, but limited in order to avoid detrimental joint openings. The reference design was supported by piers consisting of steel tubes founded in the bedrock, 30–50 m below the tunnel axis. The tunnel would consist of short immersion elements, connected to the transition structures with a flexible seismic joint. The contractor followed the same design philosophy, but chose for longer elements to reduce the number of immersion operations. Additionally, the contractor proposed a design alternative in the form of an SFT (submerge floating tunnel), which could have been the very first SFT in the world. Because of changing economic and political situation, the project was put on hold after contract close.The article describes the reference design, the bid design and the design alternative with emphasis on the seismic influence on general concept, details and construction methodology.

Laser-driven collisionless shock acceleration of protons from gas jets tailored by one or two nanosecond beams

It was proposed recently that laser-ion acceleration in gas jets may be significantly improved if each side of a gas jet target is tailored by an auxiliary nanosecond laser pulse [Marquès et al., Phys. Plasmas 28, 023103 (2021)]. In the present study, the proton acceleration by electrostatic shock in these one- or two-side tailored plasmas is investigated using particle-in-cell simulations. It is demonstrated that the formation of a thin plasma layer with a steep density profile and a maximum density of the order of the critical density strongly improves the proton acceleration in the forward direction with a maximum ion energy of tens of MeV with mildly relativistic laser pulses. Proton acceleration up to tens of MeV is predicted using realistic plasma density profiles obtained from tailored gas jet targets compared to a few MeV reported in other publications.

Evaluating CO2 capture performance by adsorption using synthesized and commercial activated carbon

ABSTRACT The rising levels of pollutants has provoked the search for advanced technologies to minimize their effect on environments. The continuous adsorption column is applied to study CO2 adsorption using two types of adsorbents. The commercial activated carbon Norit-RB2 and developed activated carbon from economic date stone are utilized for the adsorption study. The morphological and surface characteristics have been examined by BET analyzer and scanning electron microscope. The effect of flow rate, temperature, and initial adsorbate volume on breakthrough performance has been investigated. The effectiveness of the CO2 capture was examined in terms of adsorbate capacity, column efficiency, usable bed length, LMTZ, and utilization factor. The very steep adsorption profiles specify acceptable adsorbent uptake utilization under a breakthrough state. The CO2 loading of 1.66 mmol/g was reached with a column efficiency of 94.9% for biomass-derived adsorbent at 298 K temperature. The lower CO2 loading of 0.99 mmol/g and column efficiency of 92.8% have been determined for commercial activated carbon. The reduced LMTZ equal 1.29 cm and enhanced f equals to 0.974 at 298 K and Co = 5% are observed for the biomass-derived adsorbent. The findings acclaim that activated carbon derived from date pits is decidedly promising to capture CO2 by adsorption.

Breaching the Limit: Formation of GW190521-like and IMBH Mergers in Young Massive Clusters

Abstract The LIGO-Virgo-Kagra Collaboration (LVC) discovered recently GW190521, a gravitational wave (GW) source associated with the merger between two black holes (BHs) with mass 66 and >85 M ⊙. GW190521 represents the first BH binary merger with a primary mass falling in the upper-mass gap and the first leaving behind an ∼150 M ⊙ remnant. So far, the LVC has reported the discovery of four further mergers having a total mass >100 M ⊙, i.e., in the intermediate-mass black hole (IMBH) mass range. Here, we discuss results from a series of 80 N-body simulations of young massive clusters that implement relativistic corrections to follow compact object mergers. We discover the development of a GW190521-like system as the result of a third-generation merger, and four IMBH-BH mergers with total mass (300–350)M ⊙. We show that these IMBH-BH mergers are low-frequency GW sources detectable with LISA and Deci-hertz Interferometer Gravitational wave Observatory (DECIGO) out to redshift z = 0.01–0.1 and z > 100, and we discuss how their detection could help unraveling IMBH natal spins. For the GW190521 test case, we show that the third-generation merger remnant has a spin and effective spin parameter that matches the 90% credible interval measured for GW190521 better than a simpler double merger and comparable to a single merger. Due to GW recoil kicks, we show that retaining the products of these mergers require birth sites with escape velocities ≳50–100 km s−1, values typically attained in galactic nuclei and massive clusters with steep density profiles.

Hypercubes of AGN Tori (HYPERCAT). I. Models and Image Morphology

Abstract Near- and mid-infrared interferometers have resolved the dusty parsec-scale obscurer (torus) around nearby active galactic nuclei (AGNs). With the arrival of extremely large single-aperture telescopes, the emission morphology will soon be resolvable unambiguously, without modeling directly the underlying brightness distribution probed by interferometers today. Simulations must instead deliver the projected 2D brightness distribution as a result of radiative transfer through a 3D distribution of dusty matter around the AGN. We employ such physically motivated 3D dust distributions in tori around AGNs to compute 2D images of the emergent thermal emission, using Clumpy, a dust radiative transfer code for clumpy media. We demonstrate that Clumpy models can exhibit morphologies with significant polar elongation in the mid-infrared (i.e., the emission extends perpendicular to the dust distribution) on scales of several parsecs, in line with observations in several nearby AGNs. We characterize the emission and cloud distribution morphologies. The observed emission from near- to mid-infrared wavelengths generally does not trace the bulk of the cloud distribution. The elongation of the emission is sensitive to the torus opening angle or scale height. For cloud distributions with a flat radial profile, polar extended emission is realized only at wavelengths shorter than ∼18 μm, and shorter than ∼5 μm for steep profiles. We make the full results available through Hypercat, a large hypercube of resolved AGN torus brightness maps computed with Clumpy. Hypercat also comprises software to process and analyze such large data cubes and provides tools to simulate observations with various current and future telescopes.

Is automatic enrollment consistent with a life cycle model?

AbstractWe examine retirement saving for young adults in a life cycle model. We find that optimal retirement saving is zero for liquidity‐constrained young adults who anticipate significant earnings growth. With a plausible age‐earnings profile for college‐educated workers, retirement saving does not begin until the late 30s or early 40s. Workers facing a flat earnings profile begin saving much sooner. Participating may be optimal for younger workers facing steep earnings profiles if they anticipate switching jobs and cashing out after 1–2 years. Our results suggest that automatically enrolling workers, regardless of age, is not consistent with a life cycle model.

Parametric modelling of nearshore wave reflection

The importance of wave reflection on nearshore hydrodynamics has recently been acknowledged by an increasing number of studies, yet it is difficult to simulate by the conventional parametric wave transformation models widely used in coastal engineering practice. Here, we propose a simple and efficient semi-empirical method to deal with this issue. The proposed method considers wave reflections resulted from both the underwater sloping bottom and the shoreline. The former is represented by a local underwater reflection-induced energy transfer term, based on a similarity analysis of the bulk wave reflection from equivalent sloping steps. The latter is calculated as the shoreline boundary condition by utilizing a simple empirical formula of wave reflection coefficient for an emerged coastal structure. Model verifications against the previous theoretical/empirical formulas, experimental data and numerical results suggest a promising predictability of the proposed method for the cross-shore reflected wave height transformation with various bathymetry configurations. Three different formulas of the bulk reflection coefficient for an underwater sloping step are tested and compared, indicating the importance of considering slope effects in these formulas. Model results also suggest that wave reflection along a steep beach profile can be quantitatively comparable to the shoreline reflection, and it is important to include reflections of both sources in numerical modelling. The simple method can be extended and incorporated into the existing operational parametric wave models. It serves as a possible approach to simulate wave reflection with low computational demand and reasonable accuracy, and to include wave reflection influences in studying coastal processes on a broad range of time and spatial scales.

Multiple species laser-driven ion-shock acceleration

Two-dimensional particle-in-cell simulations are used to explore laser-driven collisionless shock acceleration of ions in a multi-species plasma. Simple plasma slab simulations consisting of electrons, protons, and fully ionized carbon are used, varying the carbon ionization state, the relative fraction of ions, and the ratio of downstream to upstream plasma density. We find that two shocks can simultaneously propagate with different velocities defined by the dominant ion species reflected by each shock. The appearance of two shocks allows for ions to be accelerated twice, but can also cause trapping and heating of ions. We modify the current collisionless electrostatic shock theory where ions are treated as a single fluid to include a second ion fluid. This fluid model is unable to calculate the Mach number at which both ions will reflect, therefore we propose a kinetic model that may better model multi-species shocks. Scans are also performed in simulations with a laser pulse and realistic density profile that show reduced proton peak energies with the inclusion of carbon ions. Double shocks are only seen in simulations with steep density profiles, demonstrating the experimental importance of tailored density profiles.

Modelling of Condensed Mode Cooling during the Polymerization of Ethylene in Fluidized Bed Reactors

A compartmentalized reactor model has been developed to simulate the impact of running a fluidized bed reactor for the gas-phase production of ethylene in condensed mode operation, that is, in the presence of an induced condensing agent (ICA). The reactor model captures the impact of the liquefied feed on production rates and molecular weight distributions. Particular attention has been paid to including the co-solubility and co-diffusion effects of the ICA, which are often overlooked. A criterion for defining compartment height is also proposed, and the effects of number/height of compartments in the model predictions are studied. The model is validated with patent data and shows good agreement with two sets of data from different sources. The effects of two ICAs (n-pentane and n-hexane) are studied, and it is shown that an increased ICA liquid content leads to less steep temperature profiles and increased production rates. The effects of other operating conditions such as hydrogen content, operating temperature, liquid droplet size, polymer recovery height, and liquid injection height are studied. They all showed good agreement with the available experimental results found in the literature. A scale-down exercise was also carried out where industrial and pilot-scale reactors are compared.

Composite Zn(II) Ferrocyanide/Polyethylenimine Cryogels for Point-of-Use Selective Removal of Cs-137 Radionuclides.

The feasibility of several approaches to the fabrication of monolith composite cryogels containing transition-metal ferrocyanides for Cs+ ion uptake has been evaluated. Although in the series of investigated metal ion precursors (Cu(II), Zn(II), Ni(II), and Co(II)), in situ formation of the sorption active phase in polyethyleneimine (PEI) cryogel was feasible only in the case of Zn(II) ferrocyanide, this approach has shown significant advantages over the immobilization of ex situ synthesized ferrocyanide nanoparticles. Nanoparticles of the mixed ferrocyanide Zn1.85K0.33[Fe(CN)6] formed in situ had an average size of 516 ± 146 nm and were homogeneously distributed in the monolith located at the polymer surface rather than embedded in the matrix. The Young modulus of the PEI cryogel increased after modification from 25 to 57 kPa, but composites maintained high permeability to the flow. Sorption of Cs+ ions has been investigated at superficial velocity up to 8 m/h. Steep breakthrough profiles and uptake efficiency of >99.5% until breakthrough point confirmed that a supermacroporous structure of the monolith composite assured good mass transfer, so that intraparticle diffusion was not the limiting stage of sorption kinetics. Application of the rate-constant distribution model (RCD model) to analyze the breakthrough curves of Cs+ sorption allowed the identification of two types of sorption sites with a difference in sorption rate constants of ~1 log unit. Most likely, sorption on “fast” sorption sites was governed by ion exchange between Cs+ ions in solution and K+ ions in the ferrocyanide lattice. Cs-137 radionuclide removal was investigated using the monolith composite columns of various geometries at superficial velocity up to the 6.6 m/h; specific gamma activity was reduced from 265 kBq/L to the background level, showing high potential of these materials for POU application.