Capsule Design Research Articles

Experimental determination of tin partitioning between titanite, ilmenite, and granitic melts using improved capsule designs

Abstract Investigating mineral/melt Sn partitioning at high temperatures and pressures is a difficult task because Sn is a redox-sensitive multivalent element and easily alloys with noble metal sample capsules. To obtain accurate Sn partition coefficients between titanite, ilmenite, and granitic melts, we developed single capsule Pt or Au and double capsule Pt95Rh5 (or Au)-Re designs to avoid significant Sn loss at a controlled oxygen fugacity (fO2). With these new capsule designs, we performed piston-cylinder experiments of Sn partitioning between titanite, ilmenite, and granitic melts. The experimental P-T-fO2 conditions were 0.5–1.0 GPa, 850–1000 °C, and ~QFM+8 to ~QFM-4 (quartz-fayalite-magnetite, QFM, buffer), with fO2 controlled by the solid buffers of Ru-RuO2, Re-ReO2, Co-CoO, graphite, and Fe-FeO. The obtained mineral/melt Sn partition coefficients (DSnmin/melt) are 0.48–184.75 for titanite and 0.03–69.45 for ilmenite at the experimental conditions. The DSnmin/melt values are largely dependent on fO2, although the effects of temperature and melt composition are also observed. DSnTtn/melt strongly decreases with decreasing fO2, from ~46–185 at the most oxidizing conditions (Ru-RuO2 buffer), to ~2–16 at moderately oxidizing to moderately reducing conditions (Re-ReO2 to Co-CoO and graphite buffers), to <1 at the most reducing conditions (Fe-FeO buffer). DSnIlm/melt exhibits a variation trend similar to DSnTtn/melt but is always lower than DSnTtn/melt at a given fO2. These DSnmin/melt values can be applied to quantitatively assess the mineralization potential of granitic magmas. Using DSnTtn/melt, we estimate that Sn contents are ~150–400 ppm in the pre-mineralization magmas of the tin-mineralized Qitianling plutons (South China).

3D printing novel enteric capsule shells for personalized drug delivery

Individualized drug delivery presents a viable strategy for enhancing medication efficacy and patient safety. It involves producing small batches of custom dosages tailored to each patient’s individual needs. However, current pharmaceutical manufacturing processes are not designed for personalized dosage forms. Additive manufacturing processes have great potential in the pharmaceutical industry due to the customizable nature of 3D printing technologies and the increasing demand for customized pharmaceutics and drug delivery systems. Conventional enteric capsules are prepared by dip coating to achieve gastro-resistant release, but the manufacturing process is erratic and unreliable. This study aimed to investigate the feasibility of manufacturing enteric capsules from enteric polymers using the hot melt extrusion (HME) and fused filament fabrication (FFF) process. HME was utilized to prepare filaments using enteric polymers, Hypromellose acetate succinate (HPMC-AS), and Eudragit-L 100–55, with plasticizers, sorbitol, and polyethylene glycol 4000 (PEG-4000), and a thermoplastic polymer, polyvinyl alcohol (PVA). A computer-aided design program was utilized to design size 0 capsules. The prepared capsule design and filaments were used to fabricate capsules using the FFF process. Powdered red dye was used to simulate the drug and its release from FFF fabricated capsules was evaluated in simulated gastric and intestinal fluids, pH 1.2 and 6.8, respectively. Various combinations of enteric polymer, plasticizer, and thermoplastic polymer were examined. Thermogravimetric analysis (TGA) showed that the temperatures used for processing polymer blends were well below their thermal degradation temperatures, and dye release profiles were generated using image analysis software. This study demonstrates that capsules made with HPMCAS, PEG-4000, and PVA via the FFF process are suitable for controlling drug release and that the release profile can be modified by making small changes to the formulation.

Experimental and simulation-based engineering of calcium alginate self-healing asphalt capsules

An emerging technology to mitigate the cracking of asphalt pavements is the use of self-healing capsules embedded in asphalt mixtures. In this study, self-healing capsules were fabricated by encapsulating asphalt rejuvenators with calcium alginate shells. While past studies have used a “brute force” design process for such capsules, the design and formulation of these can be optimized through careful consideration of chemical interactions and crack healing mechanisms. In this study, experiments and molecular dynamics (MD) simulation were used to engineer capsule–rejuvenator formulations to mitigate premature failure of capsules and improve self-healing efficiency. To explore the thermodynamic process, the inter-diffusion coefficient and blending degree between materials in the capsule system were evaluated at different temperatures and capsule designs to determine the ratio of capsules which survive mixing and compaction through molecular scale studies. MD provided an understanding of healing behavior by simulating and quantifying the fracture–healing–fracture process of the binder–capsule system. The experiments verified the MD model by quantifying oil release percentage from micro-extraction and recovery and fine aggregate matrix (FAM) healing efficiency. The research revealed that the interaction between asphalt binder, rejuvenator, and capsules highly depended on their chemical compositions and that the dose of capsule content influences the penetration degree, and structural failure process. Polymeric capsules experienced significant premature failure and content release at high temperatures (160 °C) compared to intermediate temperatures (25 °C) due to enhanced thermal movement. To optimize capsule performance, rejuvenators C and E, which had higher viscosities, required 30%–40% calcium alginate, while rejuvenator A with lower viscosity needed 40%–60% calcium alginate. Rejuvenators with more asphaltenes were more sensitive to the capsule shell protection effect, and strengthened healing efficiency, while rejuvenators with more aromatics resulted in better wetting and diffusion processes during healing. The healing index, derived from FAM experimental healing test and validated by simulations, indicated that approximately 40% shell material effectively prevented capsule breakage and resulted in a 50% reduction in healing capacity. This research therefore established a framework for engineering a combination of capsules for use at pavement scale based on an understanding of chemical interactions, mechanical properties, and experimental verification.

Acoustic capsule: A structure that can carry different objects but obtain the same acoustic radiation force

An acoustic capsule is designed utilizing equivalent anisotropy of density and of sound speed. The designed capsule can carry any object with dimensions smaller than those of its inner cavity. The capsule achieves internal shielding of the sound field, thus ensuring that the capsule and its contents experience the same acoustic radiation force (ARF), regardless of any changes in the contents. An acoustic capsule design method is proposed and its feasibility is verified using a combination of theoretical analysis and finite element simulations. Additionally, optimization strategies to enhance the ARF and enable selection of appropriate material parameters are discussed, and these strategies pave the way toward practical applications of the ARF in life sciences and other fields.

Measurements of Spontaneous and External Stimuli Molecular Release Processes from a Single Optically Trapped Poly(lactic-co-glycolic) Acid Microparticle and a Liposome Containing Gold Nanospheres.

We investigated the single particle kinetics of the molecular release processes from two types of microcapsules used as drug delivery systems (DDS): biodegradable poly(lactic-co-glycolic) acid (PLGA) and a light-triggered-degradable liposome encapsulating gold nanospheres (liposome-GNP). To optimize the design of DDS capsules, it is highly desirable to develop a method for real-time monitoring of the release process. Using a combination of optical tweezers and confocal fluorescence microspectroscopy we successfully analyzed a single optically trapped PLGA particle and liposome-GNPs in solution. From temporal decay profiles of the fluorescence intensity, we determined the time constant τ of the release processes. We demonstrated that the release rate of spontaneously degradable microcapsules (PLGA) decreased with increasing size, while conversely, the release rate of external stimuli-degradable microcapsules (liposome-GNPs) increased in proportion to their size. This result is explained by the differences in the disruption mechanisms of the capsules, with PLGA undergoing hydrolysis and the GNPs in the liposome-GNP undergoing a photoacoustic effect under nanosecond pulsed laser irradiation. The present approach offers a way forward to an alternative microanalysis system for single drug delivery nanocarriers.

Use of tritium-rich fuel to improve the yield of layered deuterium/tritium inertial fusion capsules

In deuterium–tritium (DT) ice layered implosions, nearly all hot spot mass at peak burn comes from the dense fuel. Accurate prediction of the fuel mass ablation, including the enthalpy associated with mass inflow into the hot spot from the dense fuel, is essential to understanding the energetics and ignition of the hot spot in layered implosions. A recently published boundary layer analysis (Daughton et al., 2023) indicates a faster mass ablation rate than in previous analyses of layered implosions. Inclusion of this effect provides a better match to simulations and leads to a new ignition threshold where the temperature of the dense fuel plays a critical role. This analysis motivates possible new directions for improved capsule performance. Here, the authors present evidence in support of one such approach: the use of tritium-rich ice to decrease 14 MeV neutron scattering and heating of the dense fuel, resulting in less mass ablation and more robust burn of the hot spot. It is found from numerical simulations that despite a less favorable D:T ratio in the ice, the use of a 40:60 D:T ratio leads to an increase in capsule yield of 17% percent compared with that of a 50:50 D:T ratio fuel for capsules resembling those of the recent N210808 ignition experiment on the NIF (Abu-Shawareb et al., 2022) and an increase of 74% compared with that of a 60:40 D:T ratio fuel capsule. These results are potentially important for modeling all layered implosions, since some degree of DT fractionization may arise naturally during the beta layering process. In addition, this physics is important for the feasibility of high-gain capsule designs that seek to minimize tritium usage, as in some inertial fusion energy concepts.

Bayesian batch optimization for molybdenum versus tungsten inertial confinement fusion double shell target design

AbstractAccess to reliable, clean energy sources is a major concern for national security. Much research is focused on the “grand challenge” of producing energy via controlled fusion reactions in a laboratory setting. For fusion experiments, specifically inertial confinement fusion (ICF), to produce sufficient energy, the fusion reactions in the ICF fuel need to become self‐sustaining and burn deuterium‐tritium (DT) fuel efficiently. The recent record‐breaking NIF ignition shot was able to achieve this goal as well as produce more energy than used to drive the experiment. This achievement brings self‐sustaining fusion‐based power systems closer than ever before, capable of providing humans with access to secure, renewable energy. In order to further progress toward the actualization of such power systems, more ICF experiments need to be conducted at large laser facilities such as the United States's National Ignition Facility (NIF) or France's Laser Mega‐Joule. The high cost per shot and limited number of shots that are possible per year make it prohibitive to perform large numbers of experiments. As such, experimental design relies heavily on complex predictive physics simulations for high‐fidelity “preshot” analysis. These multidimensional, multi‐physics, high‐fidelity simulations have to account for a variety of input parameters as well as modeling the extreme conditions (pressures and densities) present at ignition. Such simulations (especially in 3D) can become computationally prohibitive to turn around for each ICF experiment. In this work, we explore using Bayesian optimization with Gaussian processes (GPs) to find optimal designs for ICF double shell targets, while keeping computational costs to manageable levels. These double shell targets have an inner shell that grades from beryllium on the outer surface to the higher Z material molybdenum, as opposed to the nominally used tungsten, on the inside in order to trade off between the high performance associated with high density inner shells and capsule stability. We describe our results for “capsule‐only” xRAGE simulations to study the physics between different capsule designs, inner shell materials, and potential for future experiments.

Optimization of conditions for topaz irradiation in the WWR-K reactor

Abstract Activation of impurities in topazes happens due to irradiation with thermal neutrons (induced radioactivity occurs), which complicates their further handling. This leads to the need for their long cooling for safe use. The Institute of Nuclear Physics (Kazakhstan) is conducting R&D to develop a method for the effective formation of color centers in topaz during their irradiation in the WWR-K reactor. An irradiation capsule design has been developed in which optimized conditions for irradiating stones in the neutron field of the reactor are formed. The capsule uses shielding materials made of boron carbide and tantalum to cut off thermal neutrons, resulting in a reduction in induced radioactivity in topaz. The effectiveness of the irradiation capsule was tested in the core of the critical facility. As a result, thermal neutron flux is reduced by 5.7 times and the induced activity of the tantalum is reduced by 2.2 times.

Optimizing irradiation conditions for natural molybdenum in WWR-K reactor

The production of the radioisotope molybdenum-99 in the WWR-K research reactor is achieved through the activation method 98Mo(n,γ)99Mo, utilizing a target of natural molybdenum trioxide irradiated under standard conditions (thermal neutron spectra and water environment). Under such conditions, the maximum specific activity of molybdenum-99 reaches (2.3 ± 0.3) Ci/g Mo after 7 d of irradiation. However, the escalating demand for molybdenum-99 and the need to reduce its production cost, necessitates urgent and increased productivity. This study aims to optimize the irradiation conditions for molybdenum powder in the WWR-K reactor to increase the specific activity of molybdenum-99. For this purpose, we evaluated various irradiation capsule designs comprised various neutron moderator materials and thicknesses. Through extensive modeling calculations, we obtained an optimal capsule design that increases the specific activity of molybdenum-99 to 3.31 Ci per 1 g of Mo.

Simulated signatures of ignition

Ignition on the National Ignition Facility (NIF) provides a novel opportunity to evaluate past data to identify signatures of capsule failure mechanisms. We have used new simulations of high-yield implosions as well as some from past studies in order to identify unique signatures of different ignition failure mechanisms: jetting due to the presence of voids or defects, jetting due to the capsule fill tube, interfacial mixing due to instabilities or due to plasma transport, radiative cooling due to the presence of contaminant in the hot spot, long-wavelength drive asymmetry, and preheat. Many of these failure mechanisms exhibit unique trajectories that can be distinguished through variations in experimental observables such as neutron yield, down-scattered ratio (DSR), and burn width. Our simulations include capsules using both plastic and high-density carbon ablators and span all high-yield designs considered since the beginning of the National Ignition Campaign in 2011. We observe that the variability in trajectories through the space of neutron yield, DSR, and burn width varies little across capsule design yet are unique to the failure mechanism. The experimental trajectories are most consistent with simulated preheat and jetting due to voids and defects, which are the only failure mechanisms that are indistinguishable in our analysis. This suggests that improvements to capsule compression due to improved capsule quality or reduced preheat have played a primary role in enabling high yields on NIF. Furthermore, our analysis suggests that further improvements have the potential to increase yields further.

Study on crack resistance of self-healing microcapsules in asphalt pavement by multi-scale method.

Self-healing microcapsules in the asphalt pavement must be kept intact under vehicle load to ensure there is enough rejuvenator in capsules when cracks appear in asphalt pavement. In this paper, the crack resistance of self-healing microcapsules in asphalt pavement was evaluated. Firstly, an expanding multi-scale analysis was conducted based on proposed mesoscopic mechanical models with the aim to determine the mechanical parameters for the following contracting multi-scale analysis. Secondly, the periodic boundary condition was introduced for the contracting multi-scale analysis and the stress field of the capsule wall was obtained. Finally, the effects of the design parameters of the microcapsule on its crack resistance in asphalt pavement were investigated. The results showed that the incorporation of microcapsules has almost no effect on the elastic constants of the asphalt mixture. The core could be simplified as an approximately incompressible solid with the elastic constants determined by the proposed mesoscopic mechanical model. With the increase of the modulus of the capsule wall, the mean maximum tensile stress of the capsule wall increased from 0.372 MPa to 0.465 MPa, while with the decrease of the relative radius of the capsule core, the mean maximum tensile stress of the capsule wall increased from 0.349 MPa to 0.461 MPa. The change in the mean maximum tensile stress of the capsule wall caused by the change of capsule diameter was within 5%. The relative radius of the capsule core and the elastic modulus of capsule wall were two key parameters in capsule design. Besides, the microcapsules with the wall made of resin would not crack under the vehicle load before microcracks occurred in asphalt pavement.

Partitioning of tin between mafic minerals, Fe-Ti oxides and silicate melts: Implications for tin enrichment in magmatic processes

The partition coefficients of Sn (tin) between minerals and silicate melts (DSnmin/melt) are vital for understanding the Sn enrichment during magmatic processes related to tin-granites. However, experimentally determined DSnmin/melt values remain scarce due to the difficulty in avoiding severe Sn loss to noble metal capsules. In this study, we performed mineral/melt Sn partitioning experiments at 0.5–1.0 GPa, 850–1000 °C, and fO2 of FMQ + 8 to ∼ FMQ − 1. The fO2s were imposed by solid buffers of Ru–RuO2, Re–ReO2, Ni–NiO, Co–CoO and graphite using three improved capsule designs: 1) a single sample capsule (Pt) for the Ru–RuO2 buffered runs, 2) double capsules with Pt95Rh05 as outer capsule and Re as inner sample capsule for the graphite and Re–ReO2 buffered runs, and 3) triple capsules for the Co–CoO and Ni–NiO buffered runs, with Pt95Rh05 (or Au) as outer capsule, Re lined Pt as inner sample capsule. These new capsule designs avoided significant Sn loss and enabled us to obtain accurate DSnmin/melt at a controlled fO2. The experimental results show that DSnmin/melt values are 0.08–12.66 for amphibole, 0.01–5.55 for biotite, 0.09–10.39 for clinopyroxene, 0.004–0.97 for orthopyroxene, < 0.01 for olivine, 1.34–108.43 for Ti-magnetite, 0.04–4.17 for spinel and 0.10–0.64 for ilmenite. The large variation of DSn for each mineral was mainly ascribed to the effect of fO2, which results in an arresting decrease of DSn with decreasing fO2. Under the reducing conditions (fO2 < FMQ), Sn is highly incompatible (DSn < 0.1) in almost all the minerals. Modeling results indicate that partial melting at low fO2 conditions results in Sn enrichment in the derived magma, while subsequent high degree of fractional crystallization is also important for the Sn enrichment in the residual melt. The experimental and modeling results thus explain why major primary tin deposits are always related to reducing and highly fractionated granites.

Smart-responsive sustained-release capsule design enables superior air storage stability and reinforced electrochemical performance of cobalt-free nickel-rich layered cathodes for lithium-ion batteries

Nickel-rich layered oxide stands as one of the most promising cathodes in demand for higher energy density of lithium-ion batteries (LIBs) in next generation. While increasing nickel content brings more capacity, it also makes this kind of cathode more vulnerable to the ambient, both the air outside the cell and the electrolyte inside, causing aggravated storage, structural and thermal instability. The cathode surface, as the first line of defense against the ambient attack, is the essential place to address these issues. Enlightened by the mechanism of “sustained-release capsule”, here we decorate the polydimethylsiloxane (PDMS), a skin with exceptional moisture-resistance and chemical stability, onto the surface of LiNi0.9Mn0.1O2. This PDMS skin demonstrated the smart response to the surrounding environment that the hydrophobic surface guarantees the ambient air storage stability by cutting off residual alkali accumulation and the protective role of coating could be relayed as another functional mechanism once entering the battery. The detrimental HF species generated from water-induced electrolyte decomposition are effectively captured and eliminated to defend cathode corrosion and enhance interfacial stability during long-term cycling. Attributed to the seamless protection from the outside to the inside of the battery, this well-capsuled Ni-rich cathode exhibits negligible capacity fading compared with fresh state even after long ambient exposure, and realizes superior cycling and thermal stability. This work demonstrates new guidelines to design smart-responsive coatings for cathode materials to reduce their susceptibility to the surrounding environment, towards improving both ambient storage stability and cycling stability.

Reaction Capsule Design for Interaction of Heavy Liquid Metal Coolant, Fuel Cladding, and Simulated JOG Phase at Accident Conditions

High temperature corrosion of fuel cladding material (15-15Ti) in high burn-up situations has been an important topic for molten metal-cooled Gen-IV reactors. The present study aims to investigate the simultaneous impact of liquid lead (coolant side) and cesium molybdate (fuel side) on the cladding tube material. A capsule was designed and built for experiments between 600 °C and 1000 °C. In order to simulate a cladding breach scenario, a notch design on the cladding tube was investigated pre- and postexposure. Material thinning by corrosion and leaching at temperatures ≥ 900 °C caused breaches at the notches after 168 h exposure. The temperature dependent cladding thinning phenomenon was used for kinetic interpretation. As the first of a two-part study, this paper will focus on the exposure capsule performance, including metallographic cross-section preparation and preliminary results on the interface chemistry.

Electronic‐Free Traceable Smart Capsule for Gastrointestinal Microbiome Sampling

AbstractNon‐invasive smart electronic‐free sampling capsules have revolutionized the exploration of microbiome‐disease interactions in inaccessible regions of the gastrointestinal (GI) tract. However, a significant impediment to the broader use of electronic‐free capsules is the challenge of reliably tracking and determining their in vivo location. Variability in patient motility introduces uncertainties in capsule position. Thus, there is a critical need for effective solutions that ensure traceability in microbiome studies employing such capsules. While tracking methods are explored in previous smart ingestible capsule designs, most have relied on RF, imaging, and radiation‐based techniques, limiting sampling volume, increasing costs, complicating design, and raising health concerns due to ionizing radiation exposure. To address these challenges, the design of an electronic‐free smart capsule is introduced that integrates a metal tracer for easy metal detection, serving as a reliable tracking mechanism. The capsule is housed in a 3D‐printed casing and includes a superabsorbent hydrogel serving as both a sampling medium and an actuator within the capsule. The capsule's targeted sampling of the GI tract is accomplished by covering the capsule's sampling port with a pH‐responsive coating. Optimal dimensions and material for the cylindrical shaped metal tracer on the capsule are determined through extensive optimizations, considering factors such as gastric flotation, corrosion resistance, read distance, and omnidirectional detectability. The results of these investigations reveal that a 12 mm stainless steel (SS 316L) cylinder offers the necessary detection and tracing capabilities with minimal toxicity and excellent corrosion resistance under relevant physiological conditions in the GI tract. Validation studies, both in vitro and in vivo, confirmed the capsule's trackability using a handheld metal detector. These findings are further validated by X‐ray imaging and CT scans, demonstrating the metal detector's ability to distinguish approximate GI tract regions and determine the time point of excretion. This innovative approach provides a reliable and cost‐effective solution for tracking electronic‐free smart capsules, enhancing their applicability in microbiome research for both human and animal studies.

Characterization of mineral insulated cables at the WWR-K reactor: First results

At the WWR-K reactor, studies were started on the radiation resistance of signal cables with two types of mineral insulation (MgO and Al2O3). It is planned to accumulate fluence of fast neutrons ∼ 1020 cm−2 in cables. The irradiation temperature will be 500 ± 50 °C. The in-situ study of the degradation of the electrical properties of the insulation of signal cables will be carried out. This paper presents a capsule design, the results of complex calculations for the development of the capsule design, the expected neutron fluences, the dpa in steel, the technique for in-reactor measurement of electrical characteristics, and a work plan for the further studies. It is shown that the developed capsule forms the necessary conditions for irradiation. In particular, the temperature control range is 400–600 °C. The cable irradiation time until the target neutron fluence is reached will be about 100 effective days.

Aero-spike and aero-disk effects of on wave drag reduction of supersonic flow past over blunt body

PurposeThe purpose of this study is to explore the effects of aerospike and hemispherical aerodisks on flow characteristics and drag reduction in supersonic flow over a blunt body. Specifically, the study aims to analyze the impact of varying the length of the cylindrical rod in the aerospike (ranging from 0.5 to 2.0 times the diameter of the blunt body) and the diameter of the hemispherical disk (ranging from 0.25 to 0.75 times the blunt body diameter). CFD simulations were conducted at a supersonic Mach number of 2 and a Reynolds number of 2.79 × 106.Design/methodology/approachICEM CFD and ANSYS CFX solver were used to generate the three-dimensional flow along with its structures. The flow structure and drag coefficient were computed using Reynolds-averaged Navier–Stokes equation model. The drag reduction mechanism was also explained using the idea of dividing streamline and density contour. The performance of the aero spike length and the effect of aero disk size on the drag are investigated.FindingsThe separating shock is located in front of the blunt body, forming an effective conical shape that reduces the pressure drag acting on the blunt body. It was observed that extending the length of the spike beyond a specific critical point did not impact the flow field characteristics and had no further influence on the enhanced performance. The optimal combination of disk and spike length was determined, resulting in a substantial reduction in drag through the introduction of the aerospike and disk.Research limitations/implicationsTo predict the accurate results of drag and to reduce the simulation time, a hexa grid with finer mesh structure was adopted in the simulation.Practical implicationsThe blunt nose structures are primarily employed in the design of rockets, missiles, and re-entry capsules to withstand higher aerodynamic loads and aerodynamic heating.Originality/valueFor the optimized size of the aero spike, aero disk is also optimized to use the benefits of both.

Monte Carlo simulation of Mo-99 isotope production with increased specific activity in WWR-K reactor

The activation method used for the production of molybdenum-99 in the WWR-K reactor currently allows the maximum production of the specific activity of molybdenum-99 equal to (85 ± 11) GBq/g Mo as a result of seven-day neutron irradiation of natural molybdenum (VI) oxide. It is known that the reaction 98Mo(n,γ)99Mo is induced in the thermal region, and there are also large resonances in the energy region of about 12 eV and in the range of 0.4–10 keV, and these resonances do not compete with the radiative absorption reactions of other molybdenum isotopes in this area. Thus, an increase in the proportion of epithermal and thermal neutrons will lead to an increase in the production of molybdenum-99. The purpose of this work is to develop the design of an irradiation capsule that creates specified irradiation conditions. For this purpose, various designs of irradiation capsules with different materials that moderate neutrons were considered by calculation. Based on the results of Monte Carlo simulation, the optimal design of the irradiation capsule was selected, which makes it possible to increase the production of specific activity of molybdenum-99. Irradiating trioxide molybdenum with natural composition allows to increase the specific activity by 26%, while using trioxide molybdenum with a 98.7% enrichment molybdenum-98 – by 25%. The paper provides a description of the capsule designs considered and the results of computational modeling with MCNP code for molybdenum of different enrichments.

Hybrid Hydrogel-Magnet Actuated Capsule for Automatic Gut Microbiome Sampling.

Non-invasive, pill-sized capsules can provide intestinal fluid sampling to easily retrieve site-specific gut microbiome samples for studies in nutrition and chronic diseases. However, capsules with both automatic sampling and active locomotion are uncommon due to limited onboard space. This paper presents a novel hybrid hydrogel-magnet actuated capsule featuring: i) pH-responsive hydrogels that will automatically trigger fluid sampling at an environmental pH of 6 and ii) active locomotion by an external rotating magnetic field. Two capsule designs were fabricated (Design A: 31 μL sampling volume with dimensions 8 mm × 19 mm, Design B: 41 μL sampling volume with dimensions 8 mm × 21 mm). They were immersed in simulated gastric (pH = 1.2) and simulated intestinal fluid (pH = 6.8) to test for automatic intestinal fluid sampling. An external rotating magnetic field was applied to test for active locomotion. Finally, seal tests were performed to demonstrate sample contamination mitigation. Preliminary experiments showed that sampling occurred quickly and automatically in simulated intestinal fluid at 6-15 hours, active locomotion via rotation, rolling, and tumbling were possible at magnetic field magnitudes 10 mT, oil piston seals were better at mitigating sample contamination than water piston seals, and minimum o-ring seal pressures limits of 1.95 and 1.69 kPa for Design A and B respectively were sufficient against intra-abdominal pressures. This work presents the ability to impart capsule multi-functionality in a compact manner without onboard electronics or external triggering for sampling.

ЭКСПЕРИМЕНТ ПО НИЗКОТЕМПЕРАТУРНОМУ ОБЛУЧЕНИЮ ПОРОШКА ФТОРИРОВАННЫХ ДЕТОНАЦИОННЫХ НАНОАЛМАЗОВ В РЕАКТОРЕ ВВР-К: УСЛОВИЯ И ПЕРВИЧНАЯ ХАРАКТЕРИЗАЦИЯ ОБРАЗЦОВ

Fluorine-doped detonation nanodiamond (DND) powders are considered as a new class of neutron reflectors and can significantly improve the performance of very cold and ultracold neutron sources, which in turn will lead to new types of experiments at a qualitative level. These improvements are achieved due to such properties of DNDas high diffusion and quasi-mirror reflection. The high reflectivity improves the neutron delivery efficiency and, consequently, the neutron fluxes at neutron facilities. On this basis, fluorinated DNDs are considered as a potential neutron reflector material for the designed very cold and ultracold neutron source at the WWR-K reactor. However, to date, experimental data on the behaviour of fluorinated DND in the neutron field are insufficient, and therefore, in order to study the radiation resistance of DND at the WWR-K reactor, work has been started on their irradiation and further study. For this purpose, an optimal irradiation capsule design was developed and comprehensive calculations were performed to justify the conditions and limits of reactor irradiation. This paper describes the irradiated samples and reactor experiment, the methodology and conditions for irradiating the samples, and the results of their initial characterisation after irradiation.