Capsule Size Research Articles

Synergistic combination of duloxetine hydrochloride and fluconazole reduces the cell growth and capsule size of Cryptococcus neoformans.

This study aimed to evaluate the effect of duloxetine hydrochloride (DH) on Cryptococcus neoformans. DH minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were 18.5 µg/mL, and the combination with fluconazole (FLZ) reduced the MIC value by 16-and 4-fold for DH and FLZ, respectively. The capsule size decreased by 67% ​​and 16% when treated with DH and DH with FLZ, respectively. Therefore, this study showed that DH is active against C. neoformans alone and in combination with FLZ, leading to the reduction of the capsule size of this yeast.

Comparison Study between Cherry and Arabic Gums in Preparation and Characterization of Orange Peel Extract Nanocapsules

This study was aimed at determining the potential use of cherry gum (CG) and chitosan (CS) as wall materials, to encapsulate an orange peel extract (PE) via the ionic gelation method and compare its efficiency with that of Arabic gum (AG). Different ratios of chitosan to gum (1 : 1, 1 : 2, and 1 : 3, v/v) and CS to PE (1 : 0.5, 1 : 1, and 1 : 1.5, v/v) were studied to evaluate the nanocapsule properties. The results showed that the capsules entrapping the PE were successfully created with an encapsulation efficiency (EE %) of more than 80% via the ionic gelation method. The ratio of chitosan : gums and CS : PE was affecting both the encapsulation efficiency and capsule size. The capsules’ spherical shape and nanometer size were confirmed using an Atomic Force Microscope (AFM). The relative ratios 1 : 1 of CS : CG and 1 : 0.5 of CS : PE gave the highest EE% (89.27%) with an average capsule size of 70 nm, whereas the maximum EE% with AG was 97.39% with a mean size of 50 nm at the CS : PE ratio of 1 : 0.5 and AG : CS ratio of 1 : 2. The release profile of PE from the CS‐CG matrix during 240 min under acidic and alkaline conditions was about 94.45% and 98.53%, respectively, and that from the CS‐AG matrix was about 25.54% and 19.49%, respectively. The FTIR spectra confirmed the electrostatic interactions between the protonated amino group of chitosan (‐NH3+) and carboxylic ions (−COO−) of the gums. These findings indicated that the CS‐CG could be used as an efficient and ecofriendly coating material for nanoencapsulation of PE.

Combined analysis of imaging tumor capsule with imaging tumor size guides the width of resection margin for solitary hepatocellular carcinoma

BackgroundThe optimal width of resection margin (RM) for hepatocellular carcinoma (HCC) remains controversial. This study aimed to investigate the value of imaging tumor capsule (ITC) and imaging tumor size (ITS) in guiding RM width for patients with HCC. MethodsPatients who underwent hepatectomy for HCC in our center were retrospectively reviewed. ITC (complete/incomplete) and ITS (≤ 3 cm/> 3 cm) were assessed by preoperative magnetic resonance imaging (MRI). Using subgroup analyses based on ITC and ITS, the impact of RM width [narrow RM (< 5 mm)/wide RM (≥ 5 mm)] on recurrence-free survival (RFS), overall survival (OS), and RM recurrence was analyzed. ResultsA total of 247 patients with solitary HCC were included. ITC and ITS were independent predictors for RFS and OS in the entire cohort. In patients with ITS ≤ 3 cm, neither ITC nor RM width showed a significant impact on prognosis, and the incidence of RM recurrence was comparable between the narrow RM and wide RM groups (15.6% vs. 4.3%, P = 0.337). In patients with ITS > 3 cm and complete ITC, the narrow RM group exhibited comparable RFS, OS, and incidence of RM recurrence with the wide RM group (P = 0.606, 0.916, and 0.649, respectively). However, in patients with ITS > 3 cm and incomplete ITC, the wide RM group showed better RFS and OS and a lower incidence of RM recurrence compared with the narrow RM group (P = 0.037, 0.018, and 0.046, respectively). ConclusionsAs MRI-based preoperative markers, conjoint analysis of ITC with ITS aids in determining RM width for solitary HCC patients. Narrow RM is applicable in patients with ITS ≤ 3 cm regardless of ITC status and in those with ITS > 3 cm and complete ITC. Wide RM is preferred in those with ITS > 3 cm and incomplete ITC.

Macromolecular Engineering of Thermoresponsive Metal-Phenolic Networks.

Dynamic nanostructured materials that can react to physical and chemical stimuli have attracted interest in the biomedical and materials science fields. Metal-phenolic networks (MPNs) represent a modular class of such materials: these networks form via coordination of phenolic molecules with metal ions and can be used for surface and particle engineering. To broaden the range of accessible MPN properties, we report the fabrication of thermoresponsive MPN capsules using FeIII ions and the thermoresponsive phenolic building block biscatechol-functionalized poly(N-isopropylacrylamide) (biscatechol-PNIPAM). The MPN capsules exhibited reversible changes in capsule size and shell thickness in response to temperature changes. The temperature-induced capsule size changes were influenced by the chain length of biscatechol-PNIPAM and catechol-to-FeIII ion molar ratio. The metal ion type also influenced the capsule size changes, allowing tuning of the MPN capsule mechanical properties. AlIII-based capsules, having a lower stiffness value (10.7 mN m-1), showed a larger temperature-induced size contraction (∼63%) than TbIII-based capsules, which exhibit a higher stiffness value (52.6 mN m-1) and minimal size reduction (<1%). The permeability of the MPN capsules was controlled by changing the temperature (25-50 °C)─a reduced permeability was obtained as the temperature was increased above the lower critical solution temperature of biscatechol-PNIPAM. This temperature-dependent permeability behavior was exploited to encapsulate and release model cargo (500 kDa fluorescein isothiocyanate-tagged dextran) from the capsules; approximately 70% was released over 90 min at 25 °C. This approach provides a synthetic strategy for developing dynamic and thermoresponsive-tunable MPN systems for potential applications in biological science and biotechnology.

The F-Box Protein Fbp1 Regulates Virulence of Cryptococcus neoformans Through the Putative Zinc-Binding Protein Zbp1.

The ubiquitin-proteasome system (UPS) is the major protein turnover mechanism that plays an important role in regulating various cellular functions. F-box proteins are the key proteins of the UPS, responsible for the specific recognition and ubiquitination of downstream targets. Our previous studies showed that the F-box protein Fbp1 plays an essential role in the virulence of C. neoformans. However, the molecular mechanism of Fbp1 regulating the virulence of C. neoformans is still unclear. In this study, we analyzed the potential Fbp1 substrates using an iTRAQ-based proteomic approach and identified the zinc-binding protein Zbp1 as a substrate of Fbp1. Protein interaction and stability assays showed that Zbp1 interacts with Fbp1 and is a downstream target of Fbp1. Ubiquitination analysis in vivo showed that the ubiquitination of Zbp1 is dependent on Fbp1 in C. neoformans. Subcellular localization analysis revealed that the Zbp1 protein was localized in the nucleus of C. neoformans cells. In addition, both deletion and overexpression of the ZBP1 gene led to the reduced capsule size, while overexpression has a more significant impact on capsule size reduction. Fungal virulence assays showed that although the zbp1Δ mutants are virulent, virulence was significantly attenuated in the ZBP1 overexpression strains. Fungal load assay showed that the fungal burdens recovered from the mouse lungs decreased gradually after infection, while no yeast cells were recovered from the brains and spleens of the mice infected by ZBP1 overexpression strains. Thus, our results revealed a new determinant of fungal virulence involving the post-translational regulation of a zinc-binding protein.

Self‐Healable, Recyclable Anisotropic Conductive Films of Liquid Metal‐Gelatin Hybrids for Soft Electronics

AbstractThis paper reports an unconventional approach for the formation of self‐healable and recyclable anisotropic conductive films (ACFs) using soft composites of gelatin hydrogels and liquid metals (LMs). The capsules of LMs dispersed inside the gelatin matrix can present satisfactory anisotropic conductance for electrical connections of vertically aligned, fine electrodes at room temperature by applying compressive pressures. The minimization of the capsule size as well as the softness of these LM‐gelatin hybrid ACFs enables high‐resolution integrations of deformable electronic systems, which can increase the integrity of freeform devices. In addition, the good fluidity of LMs and strong hydrogen bonding in gelatin enable these ACFs to be self‐healable at ambient conditions and even recyclable with no significant degradations in either their original electrical or mechanical properties. The utilization of these ACFs to integrate multiple interconnections of micro‐light‐emitting diode arrays on a soft elastomeric substrate demonstrates a stretchable display with its reliable operations during mechanical deformations, suggesting a promising strategy for next‐generation freeform and eco‐friendly green electronics.

Novel insights into early life stages of finned octopods (Octopoda: Cirrata)

The finned or dumbo octopods (Octopoda: Cirrata) constitute a cephalopod (Mollusca: Cephalopoda) taxon almost exclusively comprising organisms that inhabit the deep-sea. This renders studying the general biology of adult cirrate specimens a difficult task, but even more so when it comes to gathering knowledge on their early life stages. During his comprehensive research exploits on cephalopod development, the late Sigurd von Boletzky (1942–2020) also sought to shed light on specific adaptations that eggs and embryos of these enigmatic deep-sea octopods might show. Based on his seminal work, the present article sets out to provide additional data on a broad range of early cirrate life stages, including egg capsules without any obvious embryonic stage as well as those containing embryos. These previously unreported specimens obtained from museum collections were analyzed using conventional morphological as well as modern three-dimensional imaging techniques. The present overview includes specimens from four of the five oceans, i.e., the Atlantic, Pacific, Indian, and Southern Ocean. Based on information on cirrate ovum, chorion, and egg capsule size as well as shape gathered from the literature, an attempt is made here for the first time to identify von Boletzky's as well as the specimens introduced here down to at least genus level. The combined data provide novel insights into early life stages of finned octopods, aiming to continue von Boletzky's legacy with regard to developmental research on a still largely enigmatic taxon of extant deep-sea cephalopods.

Three-dimensional phase diagram for the centrifugal calcium-alginate microcapsules production technology

Encapsulation techniques are used increasingly in industries such as food, cosmetic, pharmaceutical or biomedical. The most commonly used polymer for encapsulation at this day is alginate. Depending on the application, different requirements need to be satisfied by the polymer capsules. In biomedical applications, controlled shape and size of the microcapsules are desired, together with a high production frequency and the possibility to process highly concentrated biopolymer solutions. Centrifugal encapsulation has been proved to be a promising technique, capable of meeting these requirements. The centrifugal production system depends on multiple operating parameters which influence the properties of the obtained capsules. So far, insufficient data and tools are available for the system behaviour prediction and for guiding the selection of the operating parameters. Here we present an extensive parametric study on the four relevant operating parameters of the centrifugal encapsulation technology (alginate viscosity, collecting distance, needle diameter, rotating speed), leading to the derivation of comprehensive phase diagrams of capsule shapes and sizes. These tools are expected to facilitate the generalisation of the centrifugal encapsulation, by allowing for the prediction of the process behaviour, the selection of operating parameters for a desired application, and the adaptation of the technology to any available equipment. Copyright © Elsevier Inc. All rights reserved.

Encapsulation of Vitamin D3 into β-Glucan Matrix Using the Supercritical Carbon Dioxide

In this work, vitamin D3 was nanoencapsulated into the β-glucan matrix (Glu-VD3) using innovative green technology (supercritical carbon dioxide). Glu-VD3 was characterized using dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (ATR-FTIR). The particle size of the Glu-VD3 capsule was in the range 85–110 nm. FTIR revealed the interactions between the vitamin D3 (VD3) and chemical groups of β-glucan, indicating the successful entrapment of VD3 in the β-glucan. The encapsulation efficiency of VD3 was 88.31 ± 24%. Further, vitamin D3 loaded in the β-glucan matrix showed a controlled release behavior with increased antioxidant and anticancerous properties in a concentration-dependent manner. Therefore, it was concluded that the Glu-VD3 can be used as a functional ingredient in different food products to enhance the bioavailability of VD3 and protect it from thermal degradation during processing thereby enhancing the nutraceutical potential.

Metrics for implosion performance with enhanced energy coupling on NIF

In 2017–2018, record fusion yields on NIF were produced with designs that utilized high-density-carbon capsules and low-gas-fill hohlraums. Subsequently, a strategy was pursued to increase the capsule size and thus the energy absorbed by the capsule, with the latter occasionally used as a metric for these campaigns presuming that subsequent energy transfer would lead to a concomitant increase in hot-spot energy. Here we show that improved performance in recent experiments was not solely enabled by the capsule absorbed energy, which is a poor metric as it is weakly correlated with implosion performance (r ∼ 0.3). Metrics that incorporate additional information about the implosion physics or degradation mechanisms are significantly better for understanding the performance of these shots. These metrics, such as the hot-spot energy multiplied by pressure squared or the experimental ignition threshold factor (ITFX), should be used for guiding the experimental program on NIF for further improvements as they exhibit much stronger correlations with performance (r ∼ 0.8–0.9).

Fabrication of KDF-loaded chitosan-oligosaccharide-encapsulated konjac glucomannan/sodium alginate/zeolite P microspheres with sustained-release antimicrobial activity

Potassium diformate(KDF) is a non-antibiotic growth promoter. To improve the utilization of KDF in the intestinal tract, P-type zeolite molecular sieve (zeolite P) was used as the drug-binding effector of KDF and was encapsulated in sodium alginate (ALG)/konjac glucomannan (KGM)/chitosan oligosaccharide (COS) composite hydrogel microspheres to prepare environment friendly, intelligent and pH-sensitive composite hydrogel microspheres for controlling the release of KDF. The composite hydrogel microspheres were characterized using XRD, FT-IR, TGA, and SEM. In addition, the swelling behavior of the composite hydrogel microspheres in three buffered media was determined. Thus, the phase composition, structural characteristics, thermal stability, apparent morphology and swelling properties were determined. Results indicated that the composite hydrogel microspheres possessed pH sensitivity, compatibility and porous 3D network structure. Furthermore, ALG formed polyelectrolyte complexes with COS, providing the composite hydrogel microspheres a complete three-dimensional network structure. The embedded network structure of zeolite P, which limited the size of the inner capsule, assisted in improving the thermal stability, and allowed expansion and controlled release of KDF. Under a simulated gastrointestinal environment, the in vitro release conformed to a good pH-sensitive drug release pattern and prevented premature release of KDF in the gastric juice. In the in vitro antibacterial test, the maximum inhibition rate of the antibacterial agent against Escherichia coli, Staphylococcus aureus and Bacillus subtilis were 96.63%, 93.81% and 93.31%, respectively, indicating its considerable potential as an intestinal antibacterial.

Cyclic performance of cascaded latent heat thermocline energy storage systems for high-temperature applications

The cyclic performance of cascaded latent heat thermocline energy storage systems for high-temperature applications is presented. To investigate this performance, a transient, two-phase numerical model is established based on a concentric-dispersion approach. The storage unit is filled with encapsulated phase change materials (PCMs) having different melting points. Molten salt serves as a heat transfer fluid. The general behavior of the three-PCM cascade system is firstly analyzed. Secondly, the effects of PCMs filling fractions of two and three cascade structures are studied. Lastly, the effects of latent heat and capsule diameter are investigated based on the optimal cascade structure performance of the above analyses. The results show that as the volume fraction of bottom PCM increases than top PCM, the system's performance enhances in terms of heat storage and release. The arrangement wherein the bottom PCM occupies half of the bed height has the highest capacity and total utilization ratios of 83% and 40.5%, respectively. The effect of latent heat has a considerable impact on cyclic performance. The scenario wherein top and bottom PCMs have high latent heat, exhibits the greatest benefits compared to other scenarios. The results also show that the smaller capsule size achieves the best behavior. When the capsule diameter increases from 1.9 cm to 4.2 cm, the total storage capacity decreases by 34.8%; the energy recovered declines by 10%; the total utilization ratio decreases by 13.77%, and the capacity ratio decreases by 1.7%.

Melting and energy storage characteristics of macro-encapsulated PCM-metal foam system

In this study a novel encapsulated phase change material (PCM)-metal foam hybrid system is proposed for energy storage applications. The idea is to improve the melting rate of PCM in encapsulated PCM systems with the introduction of metal foam structures inside the capsules. The main objective of the work is to develop a numerical model which can simulate the melting of PCM in this hybrid system due to the flow of heat transfer fluid (HTF) around the capsule with the resolution of the metal foam geometry at the pore-scale level. The developed model couples geometry creation, phase change and fluid flow models. The foam geometry is created using overlapping circular pores with random location, radii, and overlap. The phase change model is developed by modifying the enthalpy method to incorporate the presence of four phases – HTF, metal, solid PCM, and liquid PCM. This is coupled with an implicit flow solver within a finite volume framework. An in-depth analysis of a base case is conducted by fixing different geometrical parameters such as capsule size, porosity, pore size distribution and shell thickness. The results of the base case are then compared in subsequent parametric studies, by varying one geometrical parameter at a time. The parametric studies reveal that the structure of the metal foam plays an important role in determining the melting pattern and the energy storage characteristics because of its net-like large inner surface area. It is found that the melting time is reduced for lower capsule size, lower porosity, and higher shell thickness. The average pore size and range are crucial in determining the rate of melting.

Synthesis of uniform submicron poly(lactic acid)-based particles/capsules by radical precipitation polymerization

Poly(l-lactic acid) (PLLA) is a well-known biopolymer, usually synthesized via step-growth or ring-opening polymerization from lactic acid or a lactide monomer, respectively. PLLA microspherical particles are produced by dispersion polymerization with a ring-opening lactide monomer using a particular copolymer chain as a stabilizer. This is not easy to achieve when dehydration is needed. Here, a robust and simple synthesis of a nearly monodisperse, submicron PLLA-based particle/capsule was proposed via radical precipitation polymerization without the use of surfactant. A commercial PLLA was first glycolyzed with ethylene glycol to obtain a low molecular weight glycolyzed PLLA (GPLLA). Then, the GPLLA was copolymerized with methacrylic acid and ethylene glycol dimethacrylate monomers using a benzoyl peroxide initiator. Active sites on the GPLLA backbone were generated by hydrogen abstraction of benzoyloxy radicals that further copolymerized before self-assembly to form the polymer particles. Uniform particle size of about 580 nm with a low polydispersity index (PDI) of 0.012 was obtained. This method was also implemented to produce nearly monodisperse capsules containing linalool. The particle size of PLLA-based capsules was about 280 nm with narrow particle size distribution (PDI of 0.120). The PLLA-based capsules effectively inhibited microbial growth of Staphylococcus aureus, Escherichia coli and Candida albicans and were not toxic to human cells.

Encapsulation of Enzymes in Metal-Phenolic Network Capsules for the Trigger of Intracellular Cascade Reactions.

Nanoengineered capsules encapsulated with functional cargos (e.g., enzymes) are of interest for various applications including catalysis, bioreactions, sensing, and drug delivery. Herein, we report a facile strategy to engineer enzyme-encapsulated metal-phenolic network (MPN) capsules using enzyme-loaded zeolitic imidazolate framework nanoparticles (ZIF-8 NPs) as templates, which can be removed in a mild condition (e.g., ethylenediaminetetraacetic acid (EDTA) solution). The capsule size (from 250 nm to 1 μm) and thickness (from 9.8 to 33.7 nm) are well controlled via varying the template size and coating time, respectively. Importantly, MPN capsules encapsulated with enzymes (i.e., glucose oxidase) can trigger the intracellular cascade reaction via the exhaustion of glucose to produce H2O2 and subsequently generate toxic hydroxyl radicals (•OH) based on the Fenton reaction via the reaction between H2O2 and iron ions in MPN coatings. The intracellular cascade reaction for the generation of •OH is efficient to inhibit cancer cell viability, which is promising for the application in chemodynamic therapy.

Preparation and characterization of SiO2@n-octadecane capsules with controllable size and structure

In this work, a series of SiO2@n-octadecane capsules were prepared by one step emulsion polymerization, the influence of emulsifying speed, ammonia and TEOS contents, reaction temperature, concentration of emulsifier and the amount of PVP on the size, structure and performance was detailed investigated. It can be seen from SEM characterization that among these factors emulsification speed had the greatest influence on capsule size, while followed by the ammonia and TEOS content. According to TEM results, the ammonia and TEOS contents were the most important factors on the structure (shell thickness and surface smoothness) of the capsules, attributing to ammonia and TEOS were the catalyst and reactant of hydrolysis polymerization, respectively. Generally, the crystallinity of the samples became worse as the size decreased. DSC results showed that excessive ammonia or TEOS caused a significant drop in the enthalpy of the samples, furthermore, the enthalpy basically decreased with the attenuation of the inner radius of the sample. The target SiO2@n-octadecane capsule was sample C2 with high enthalpy (127.7 J/g), size of 1.62 μm, shell thickness of 68 nm, and smooth surface. More importantly, within the parameters studied, a series of SiO2@n-octadecane capsules were successfully synthesized with different enthalpy values (min 85.9 J/g, max 144.3 J/g), sizes ranging from 0.63–2.75 μm, shell thickness 32–79 nm and different smooth surfaces. Therefore, the controllable synthesis of SiO2@n-octadecane capsules within the above range can be achieved by simulating different parameters and their development.

Prediction of melting characteristics of encapsulated phase change material energy storage systems

This paper presents a numerical study of encapsulated phase change material (PCM) energy storage systems consisting of a single capsule or multiple capsules with different arrangements. A numerical model is developed for predicting the melting characteristics of encapsulated PCM with circular geometry, subjected to the flow of heat transfer fluid (HTF) over the capsules. The model also incorporates the effect of natural convection inside the PCM capsules. The single capsule system is analyzed to capture the effect of different parameters such as capsule size, fluid temperature, fluid velocity, and direction of flow. The model is applied to investigate multiple capsule systems to enhance the melting rate by the effective distribution of PCM capsules. Straight and alternate arrangements are compared for a varying number of capsules by maintaining the same latent energy storage capacity. Parametric studies are also performed for multiple capsule systems. Subsequently, a novel design of graded systems is proposed for improving the multi-capsule system by reducing the total duration of melting. The capsules are arranged with a percentage reduction in size along the flow direction, keeping the overall energy storage capacity constant. Simulation results show that there exists an optimum value of the reduction percentage for which the melting time is lowest.

Lambda-cyhalothrin-loaded nanocapsules pose an unacceptable acute toxicological risk to zebrafish (Danio rerio) at the adult and larval stages but present an acceptable risk to embryos

Recently, size-controlled pesticide microcapsule (MC) delivery systems have played an important role in precision farming development; however, the potential environmental hazards of MCs with different particle sizes have not been fully characterized. In this study, we prepared a series of lambda-cyhalothrin (LC)-MCs with nano and micron-scale capsule sizes (average diameters of 209.4 nm, MC-N; 2.41 µm, MC-S; 4.87 µm, MC-M; and 12.41 µm, MC-L). The assessment results showed that the release and sedimentation behavior of LC-MCs in water and toxicity to zebrafish at three life stages were all particle size-dependent. As the diameter distribution of approximately 100 nm extended to the micron scale (~27 µm), the capsules released more slowly and sunk more quickly in water. In addition, micron-sized LC-MC exposure resulted in significantly less fish mortality and malformations of larvae and embryos compared with nanosized LC-MC exposure. The highest accumulation of MC-N in the gill and the severest toxicity to larvae suggested that the smaller size and stronger permeability of nanocapsules would pose unpredictable consequences for nontargeted organisms. The obvious toxicological differences of LC-MCs toward aquatic organisms implies that regulating MC production in an appropriate size range is an important prerequisite for achieving efficient but safe pesticide applications.

Reaching 30% energy coupling efficiency for a high-density-carbon capsule in a gold rugby hohlraum on NIF

In the laser-driven indirect drive scheme for inertial confinement fusion, the energy coupling efficiency from the hohlraum to the capsule is typically ∼10% due to limited capsule sizes in order to attain quasi-round implosions with currently available laser energy in cylindrical hohlraums. Recent experiments at the National ignition Facility (NIF) showed ∼30% energy coupling efficiency to aluminum capsules by using a rugby-shaped hohlraum to accommodate larger capsules. This paper reports the first experiment at the NIF demonstrating ∼30% energy coupling to a 3 mm-diameter high-energy-density carbon capsule in a rugby hohlraum with a two-shock laser pulse shape. By comparing the measured bang time with a simulated hydrodynamic scaling, ∼430 kJ coupling is inferred with 1.36 MJ laser drive. The symmetry of the hot spot was observed to be more oblate than simulations predicted. X-ray images taken at late time show strong emission at the laser entrance hole of the rugby hohlraum, indicating a closure earlier than expected, which could contribute to the oblate hot spot shape. Implementing wavelength detuning or modifying the hohlraum shape to tune the symmetry in future experiments would allow symmetric implosions while maintaining the high energy coupling.

Achieving record hot spot energies with large HDC implosions on NIF in HYBRID-E

HYBRID-E is an inertial confinement fusion implosion design that increases energy coupled to the hot spot by increasing the capsule scale in cylindrical hohlraums while operating within the current experimental limits of the National Ignition Facility. HYBRID-E reduces the hohlraum scale at a fixed capsule size compared to previous HYBRID designs, thereby increasing the hohlraum efficiency and energy coupled to the capsule, and uses the cross-beam energy transfer (CBET) to control the implosion symmetry by operating the inner (23° and 30°) and outer (44° and 50°) laser beams at different wavelengths (Δλ&amp;gt; 0). Small case to capsule ratio designs can suffer from insufficient drive at the waist of the hohlraum. We show that only a small amount of wavelength separation between the inner and outer beams (Δλ 1–2 Å) is required to control the symmetry in low-gas-filled hohlraums (0.3 mg/cm3 He) with enough drive at the waist of the hohlraum to symmetrically drive capsules 1180 μm in outer radius. This campaign is the first to use the CBET to control the symmetry in 0.3 mg/cm3 He-filled hohlraums, the lowest gas fill density yet fielded with Δλ&amp;gt; 0. We find a stronger sensitivity of hot spot P2 in μm per Angstrom (40–50 μm/Å wavelength separation) than observed in high-gas-filled hohlraums and previous longer pulse designs that used a hohlraum gas fill density of 0.6 mg/cm3. There is currently no indication of transfer roll-off with increasing Δλ, indicating that even longer pulses or larger capsules could be driven using the CBET in cylindrical hohlraums. We show that the radiation flux symmetry is well controlled during the foot of the pulse, and that the entire implosion can be tuned symmetrically in the presence of the CBET in this system, with low levels of laser backscatter out of the hohlraum and low levels of hot electron production from intense laser–plasma interactions. Radiation hydrodynamic simulations can accurately represent the early shock symmetry and be used as a design tool, but cannot predict the late-time radiation flux symmetry during the peak of the pulse, and semi-empirical models are used to design the experiments. Deuterium–tritium (DT)-layered tests of 1100 μm inner radius implosions showed performance close to expectations from simulations at velocities up to ∼360 km/s, and record yields at this velocity, when increasing the DT fuel layer thickness to mitigate hydrodynamic mixing of the ablator into the hot spot as a result of defects in the ablator. However, when the implosion velocity was increased, mixing due to these defects impacted performance. The ratio of measured to simulated yield for these experiments was directly correlated with the level of observed mixing. These simulations suggest that reducing the mixing, e.g., by improving the capsule defects, could result in higher performance. In addition, future experiments are planned to reduce the coast time at this scale, delay between the peak compression and the end of the laser, to increase the hot spot convergence and pressure. To reduce the coast time by several hundred ps compared to the 1100 μm inner radius implosions, HYBRID-E has also fielded 1050 μm inner radius capsules, which resulted in higher hot spot pressure and a fusion energy yield of ∼170 kJ.